Species list of the European herpetofauna – 2020 update by the Taxonomic Committee of the Societas Europaea Herpetologica

Caudata/Urodela

A series of phylogenetic studies on mitochondrial DNA, allozymes, and nuclear DNA sequences of members of the family Salamandridae (Litvinchuk et al., 2005; Weisrock et al., 2006; Zhang et al., 2008; Kieren et al., 2018; Veith et al., 2018) confirmed that the newt genus Triturus sensu lato, as traditionally recognised, is not monophyletic. Litvinchuk et al. (2005) proposed the separation of Triturus into four genera, among which the new genus Ommatotriton contains (the former) Triturus vittatus. SBC2010 accepted this new arrangement, but did not explicitly acknowledge the need to recognise Ommatotriton, as the new genus does not occur in the area they considered. As we herein consider a wider area, we formally accept Ommatotriton as a separate genus.

Litvinchuk et al. (2005) also showed that morphology (number of trunk vertebrae, colour pattern), genome size, and allozymes (Nei’s genetic distances of 0.44-0.83) strongly differ between populations in the two widely disjoint areas inhabited by Ommatotriton vittatus, namely south-eastern Anatolia and the Levant (O. v. vittatus) versus the southern and eastern Black Sea and western Caucasus regions (O. v. ophryticus). This led them to elevate ophryticus to species level. A more comprehensive study also demonstrated restricted introgression between an eastern and a western taxon along the Black Sea coast of Turkey (van Riemsdijk et al., 2017). Consequently, we recommend to recognise three species in the genus Ommatotriton: O. vittatus (extralimital) in south-eastern Anatolia and the Levant, O. ophryticus in Russia, the Caucasus and northern Anatolia west to the region of Samsun, and O. nesterovi (extralimital) in Anatolia from Samsun to the Sea of Marmara. The populations inhabiting the native Ommatotriton range in the European part of Russia belong to O. ophryticus, while the introduced (and persisting anno 2019; Speybroeck, pers. obs.) population in north-eastern Spain is of mixed ancestry, with genetic contribution from both O. ophryticus and O. nesterovi (van Riemsdijk et al., 2018).

In addition to mtDNA sequences, Vences et al. (2014) used sequences from thirteen nuclear loci to improve our understanding of the history of the genus Salamandra. Their nuclear data suggest that Salamandra salamandra contains several deeply divergent lineages whose monophyly relative to S. algira received weak support, although this requires confirmation. Based on mitochondrial data the subspecies longirostris is sister to all other S. salamandra lineages. However, nuclear genes place it with the subspecies morenica. The discordance between mtDNA and nuclear genes may result from past introgression and admixture processes. Furthermore, a clade comprising the subspecies fastuosa, bernardezi (including populations attributed to the subspecies alfredschmidti, whose validity was rejected, as it is phylogenetically nested within several subclades of bernardezi; Beukema et al., 2016) and gigliolii is recovered with strong support. While additional data are clearly needed, this suggests a high amount of evolutionary divergence within S. salamandra, and the existence of more than one species within S. salamandra cannot yet be fully ruled out.

SBC2010 recognised two species within the former Triturus karelinii: T. arntzeni from the Balkan Peninsula, and T. karelinii. Wielstra et al. (2013) suggested that the type specimens of T. arntzeni are in fact T. macedonicus, which led them to place T. arntzeni in the synonymy of T. macedonicus, and to create the name ivanbureschi for the taxon of the karelinii complex that occurs in the Balkans and in Western Anatolia. Later, Wielstra and Arntzen (2014) demonstrated that the types of T. arntzeni are in fact the result of ancient admixture between T. macedonicus and T. ivanbureschi. We do not entirely agree with their interpretation of the Code. As they rightfully state, nomina based on genetically admixed individuals derived through several generations of backcrossing are indeed left in limbo in the Code. Yet, we do not agree that the Code should be interpreted as extending provisions of Art. 23.8 to nomina based on genetically admixed individuals, at least not without clear guidelines of what constitutes admixture in the sense of the Code. We do, however, agree with Wielstra and Arntzen (2014) that arntzeni, based on individuals that carry less than 50% of alleles derived from the karelinii-complex taxon, should not be used as the valid name for that taxon. We thus accept T. ivanbureschi as the valid nomen of the taxon of the karelinii-complex that occurs in Europe in the Balkans. With the extension of the geographic range of SBC2010, T. karelinii sensu stricto also occurs in our area in Russia, the Crimean Peninsula and the Caucasus region.

Using mitochondrial and nuclear DNA sequences, Sotiropoulos et al. (2007) and Recuero et al. (2014) investigated the phylogenetic structure of Ichthyosaura alpestris. They identified several deeply divergent lineages that largely correspond to currently recognised subspecies, except for the subspecies alpestris, which is further divided into a western and an eastern main lineage. Interestingly, nuclear sequences from two loci show a nearly complete lack of allele sharing between the eastern and western clades, suggesting reproductive isolation between them. However, no samples were collected close to their contact zones. As the eastern and western clades should meet in the Balkans and the southern Carpathian Mountains, we follow the recommendation of Recuero et al. (2014) and await more data on their level of reproductive isolation before making any taxonomic change. Thus, we do not follow Raffaëlli (2018) who (based on the genetic data presented in the aforementioned studies) elevated the subspecies apuana, reiseri and veluchiensis to species level, and we note that such changes would make I. alpestris polyphyletic. We thus retain I. alpestris as a single species for now.

Pabijan et al. (2017) reconstructed phylogenetic relationships within the Lissotriton vulgaris species complex and inferred patterns of (historical) gene flow, using 74 nuclear DNA markers from one individual from each of 127 locations. Five highly divergent lineages were identified within our focal area: Lissotriton montandoni and four lineages corresponding to the Lissotriton vulgaris subspecies graecus, lantzi, schmidtleri and vulgaris. In spite of clear evidence of past historical introgression, their contemporary gene flow is restricted. Therefore, the authors proposed to treat the three former subspecies as species (Pabijan et al., 2017). Between L. v. vulgaris and the morphologically diverged L. v. meridionalis regular episodes of gene flow were identified, thus meridionalis was retained at subspecies level. While L. v. graecus is easily distinguished from other European populations by male nuptial characteristics, both L. v. lantzi and L. v. schmidtleri are morphologically cryptic in respect to L. v. vulgaris (Raxworthy, 1990). Rather than being confined to Anatolia, Pabijan et al. (2015, 2017) showed that L. v. schmidtleri also occurs in Greek and Turkish Thrace and on a number of Greek islands. Because the sampling gaps between several of the lineages remained wide, the TC has been reluctant to accept all systematic conclusions of Pabijan et al. (2017). The taxon graecus comes into close contact with L. v. vulgaris along the northern and eastern borders of its distribution. Although no dense sampling has been performed to delineate the contact zone in detail, and mitochondrial introgression from southern L. v. vulgaris into graecus occurs at its northern range border (Pabijan et al., 2017), nuclear gene pools of these two taxa appear to remain reciprocally distinct in relative close geographical proximity (Pabijan et al., 2017; Wielstra et al., 2018). We therefore accept Lissotriton graecus as a valid species. For L. v. schmidtleri, its range limits and contact zones with other European lineages remain poorly known. Although data on the contact zone with L. v. kosswigi in Anatolia support a species-level divergence between L. v. schmidtleri and the graecus-kosswigi clade, areas of 100-300 km inhabited by L. vulgaris s.l. of unknown identity separate genotyped L. v. schmidtleri populations from those of L. v. vulgaris and L. graecus (Pabijan et al., 2017; Wielstra et al., 2018). The TC thus feels that more information on contact zones between L. v. schmidtleri and L. v. vulgaris is warranted before the species rank of schmidtleri can be accepted. Finally, L. v. lantzi is endemic to the Caucasus and shows an allopatric distribution (Wielstra et al., 2018). Mitochondrial data suggests that L. v. lantzi was the first to diverge from other lineages around 3.39 (1.42-5.37) Mya (Pabijan et al., 2015). Yet, nuclear data place L. v. lantzi as sister to L. v. schmidtleri and other eastern and central European Lissotriton, while suggesting that divergence within this group initiated with the split of the graecus-kosswigi clade (Pabijan et al., 2017). In conclusion, the TC recommends to treat Lissotriton graecus as a valid species, but, as awarding species status to lantzi but not to schmidtleri may render L. vulgaris paraphyletic, we prefer to maintain the other taxa, including L. v. schmidtleri and L. v. lantzi, as subspecies of L. vulgaris for the time being.

A phylogeographic study based on two mtDNA markers by Martínez-Solano et al. (2006) revealed two major mitochondrial lineages of Miocene origin in Lissotriton boscai. One of them is restricted to central and south-western coastal Portugal, while the other occupies the remainder of the species range, including the type locality of L. boscai. Martínez-Solano et al. (2006) acknowledged that the two lineages might represent cryptic species, but called for additional morphological and molecular studies, including data on variation in nuclear DNA markers. Dubois and Raffaelli (2009) resurrected the nomen Triton maltzani Boettger, 1879 for the southwestern lineage in the new combination Lissotriton maltzani. According to these authors, L. maltzani can be distinguished from L. boscai by its smaller size and by its paler dorsal coloration, especially in females, with less distinct dark spots. Teixeira et al. (2015) used DNA sequences of one nuclear gene and found overall congruence with mtDNA genes in terms of sequence divergence and geographic structure. They, however, also revealed wide areas of admixture and evidence for recombination, suggesting a lack of complete reproductive isolation and the presence of incomplete speciation. In a recent study, Sequeira et al. (2020) used ten microsatellites, one mtDNA gene and two single copy nuclear DNA markers in a cline analysis framework to investigate one of the hybrid zones between L. boscai and L. maltzani. The results show evidence for partial reproductive isolation between L. boscai and L. maltzani, with narrow clines (3-28 km) consistent with selection against hybrids. We thus recognise L. maltzani as a separate species.

Wake (2012) addressed the taxonomy of the Plethodontidae, advocating to treat Atylodes (comprising Speleomantes genei) and Speleomantes (comprising the other European plethodontid species) as subgenera of a single, cross-Atlantic genus Hydromantes. Addressing the genus name confusion, Wake (2013) compared five potential arrangements, missing however the arrangement of SBC2010 (i.e. two genera without subgenera). Comparing with other plethodontid genera, he argued in favour of an arrangement of a single genus with three subgenera. However, the arguments of SBC2010 still stand: the position of Atylodes remains unresolved, and the European species form a well-defined monophyletic group with a large genetic distance from the five Californian species Hydromantes brunus, H. platycephalus, H. samweli, H. shastae, and H. wintu (Nascetti et al., 1996; Pyron and Wiens, 2011; Chiari et al., 2012b; Bingham, Papenfuss and Wake, 2018). Thus, no change seems in order, and we maintain the European species for the time being in a single taxon, the genus Speleomantes.

Vörös, Ursenbacher and Jelić (2019) used 10 microsatellite loci to investigate patterns of differentiation between four Croatian cave populations of Proteus anguinus. They uncovered long-lasting isolation between caves belonging to different hydrogeographic systems, with the most ancient divergence being older than 7 Mya. This suggests that some of the evolutionary lineages within this species might constitute cryptic taxa, possibly of species rank (Vörös, Ursenbacher and Jelić, 2019).

Anura

Alytes obstetricans is composed of four subspecies: A. o. obstetricans, A. o. pertinax, A. o. boscai and A. o. almogavarii. The latter taxon is endemic to Catalonia and adjacent areas in north-eastern Spain and southern France, and it is highly differentiated in allozyme (Arntzen and García-París, 1995; García-París, 1995), mitochondrial (Gonçalves et al., 2007, 2015) and microsatellite markers (Maia-Carvalho et al., 2018), and features peculiar osteological (Martínez-Solano et al., 2004) and bioacoustics characters (Márquez and Bosch, 1995). Possibly due to ancestral hybridisation or incomplete lineage sorting (Gonçalves et al., 2007; Maia-Carvalho et al., 2014), the nuclear phylogeny, based on intron sequences, is not well resolved. Using microsatellites, Maia-Carvalho et al. (2018) identified a distinct cluster corresponding to all A. o. almogavarii populations, suggesting that the lack of monophyly in mtDNA data is due to cyto-nuclear discordance. This cluster extends as far west as the southern slopes of the Pyrenees in the north-westernmost parts of Aragon. These authors also found restricted genetic admixture between A. o. almogavarii and neighbouring subspecies (A. o. pertinax, A. o. obstetricans). Following up on this study, Dufresnes and Martínez-Solano (2020) targeted the hybrid zone between A. o. almogavarii and A. o. pertinax with genomic analyses using RADseq-derived markers along a fine-scale transect in Catalonia. They documented a very narrow mitochondrial (cline width ca. 13 km) and nuclear (cline width ca. 16 km) transition, and detected portions of the genome that were completely impermeable to gene flow. Given the absence of barriers to dispersal in the contact zone, the authors concluded that these lineages exhibit substantial (even if incomplete) reproductive isolation. We adopt their recommendation and treat Alytes almogavarii as a distinct species.

Pabijan et al. (2012) found a lack of reciprocal monophyly in nuclear data of Iberian painted frogs (Discoglossus spp.), while Dufresnes et al. (2020a) found numerous introgressed individuals in their RAD datasets and a broad hybrid zone (average cline width of nuclear markers >136 km). These results indicate weak (or no) restriction to gene flow and confirm that D. g. galganoi and D. g. jeanneae are better treated as conspecific, as previously advocated by SBC2010.

Borkin et al. (2001) reported differences in genome size between the morphologically similar eastern and western populations of Pelobates fuscus, with a transition between both groups in north-eastern Ukraine and adjacent parts of Russia. The name Rana vespertina Pallas, 1771 is available for the eastern taxon. Subsequently, analyses using mtDNA data across the entire species range confirmed the existence of two major mitochondrial lineages (Crottini et al., 2007). Litvinchuk et al. (2013) confirmed that these two lineages differ in their nuclear genomes, with Nei’s genetic distance based on allozymes being similar to the divergence between Pelobates syriacus syriacus and P. s. balcanicus (see below), and with a restricted introgression zone. Based on its independent evolutionary history, they thus proposed to treat vespertinus as a species. More recently, based on RADseq data, Dufresnes et al. (2019a) reported narrow clines between fuscus and vespertinus (average nuclear cline width: 16 km). On the basis of the narrow hybrid zone, indicating strong (albeit incomplete) reproductive isolation, and in spite of the relatively recent divergence of this taxon (between 2 and 3 Mya, see Dufresnes et al., 2019a, b), we accept the specific rank of Pelobates vespertinus.

Dufresnes et al. (2019a) also demonstrated complete reproductive isolation between Pelobates syriacus syriacus and P. s. balcanicus, warranting elevation of European populations, except those from south-eastern Bulgaria, parts of European Turkey and a number of eastern Greek islands (including Limnos and Lesbos), to species level as Pelobates balcanicus, with an estimated Mio-Pliocene divergence (>5 Mya) between both taxa. Deep intraspecific divergence within each species further leads to recognise the subspecies P. balcanicus chloeae (Peloponnese) and P. syriacus boettgeri (all European parts of the distribution of Pelobates syriacus).

The complex pattern of genetic variation within Iberian Pelodytes has been known for several years (e.g., van de Vliet et al., 2012). It was taxonomically formalised by Díaz-Rodríguez et al. (2017), who described two new species: Pelodytes atlanticus from Portugal and P. hespericus from central eastern Spain, in addition to the previously established species, P. ibericus and P. punctatus. The two new lineages show no consistent morphological or bioacoustics differences, are only weakly differentiated in mtDNA (<2% in the 16S rRNA gene, <7% in COI), but show limited sharing of nuclear alleles. Díaz-Rodríguez et al. (2017) recognised that this was a disputable case, in which, for the time being, “species status for all four western lineages of Pelodytes [was] the hypothesis best fitting the available data”. A new study by Dufresnes et al. (2020a), based on RADseq-derived loci from spatially dense sampling, found that P. atlanticus and P. ibericus are separated by a narrow hybrid zone, featuring little introgression, whereas the contact zone of P. hespericus and P. punctatus has a considerably more flattened cline, with an introgression zone possibly extending up to 200-300 km. There is no known contact zone between P. atlanticus and P. hespericus. While the position of P. atlanticus (sister to ibericus or to hespericus) remains unresolved, its genetic divergence from hespericus and punctatus is quite large. We thus follow the suggestion of Dufresnes et al. (2020a) to accept P. atlanticus as separate species, while retaining hespericus at subspecies level as P. punctatus hespericus.

Despite growing support for recognition of various clades in the family Bufonidae as separate genera (Stöck et al., 2006; Van Bocxlaer et al., 2009), several authors advocated retaining Bufo for all species from the Western Palaearctic and Central Asia, at least as an ad interim solution (Dubois and Bour, 2010; SBC2010). Formal taxonomic action was further hampered by nomenclatural confusion, such as the use of either Pseudepidalea or Bufotes as the valid generic nomen for the green toad group (Frost et al., 2006; Dubois and Bour, 2010). Dubois and Bour (2010) demonstrated that Pseudepidalea is a junior objective synonym of Bufotes, thereby giving priority to the latter. However, based on the presence of hybridisation between representatives of these clades, and the restricted sampling size of previous studies, Dubois and Bour (2010) listed these nomina as subgenera, rather than genera. According to Van Bocxlaer et al. (2010), Pyron and Wiens (2011), and Beukema et al. (2013), which together provide a dense sampling of bufonid species, most genera currently recognised by Frost (2019) represent well-supported monophyletic units. Moreover, time-calibrated analyses showed Bufo, Bufotes and Epidalea to be of similar age as or older than most other recognised bufonid genera (Beukema et al., 2013). Considering these results, we accept Bufo, Bufotes and Epidalea at genus level.

Recuero et al. (2012) published a multilocus mitochondrial and nuclear DNA sequence data set for Bufo bufo and associated species, covering the entire documented range and providing extensive genetic data. The study yields a fully resolved phylogeny, with the recently described Bufo eichwaldi from the Talysh Mountains of southern Azerbaijan and northern Iran as the sister taxon of a clade including three deeply diverged lineages: i) north African, Iberian, and most French populations of Bufo bufo (for which the name Bufo spinosus is available), and a clade composed of two lineages, representing ii) verrucosissimus from the Caucasus and iii) bufo from northern France to Russia, while populations from Greece, southern Italy and Sicily and most of Anatolia carried bufo mtDNA but grouped with verrucosissimus in nuclear DNA. Estimations of divergence times indicated a long evolutionary history of the group, starting with the split from eichwaldi at about 12 Mya, and the divergence of spinosus taking place around 6 Mya. The deep level of genetic divergence observed between the western and eastern groups of common toads indicated that these groups may be different species. However, Garcia-Porta et al. (2012) found extensive admixture of mitochondrial lineages between the eastern and western clades in the Languedoc area of southern France (as also reported by Arntzen et al., 2017 for the Provence area of southern France), and detected signs of ancient introgression of bufo allozyme alleles into spinosus. They thus suggested to treat B. b. spinosus and B. b. bufo as conspecific pending studies of the contact zones. Detailed analysis of the amount of reproductive isolation in two geographically distant contact zones on the basis of mtDNA, morphology and nuclear markers have subsequently been published by Arntzen et al. (2016, 2017). Both studies documented an extensive amount of hybridisation and introgression in the contact zone, but also the presence of narrow and concordant clines for most nuclear markers, resulting in a unimodal, yet narrow hybrid zone of ca. 30 km wide, and indicating intrinsic barriers to gene flow in spite of incomplete reproductive isolation. Karyological analysis (albeit based on only four males and a single female) identified heteromorphic sex chromosomes in spinosus, but not in bufo (Skorinov et al., 2018). The combined available evidence justifies treating Bufo spinosus as a distinct species.

Based on differences in morphology and karyotype and a study suggesting lowered fertility of F1 hybrids (summary in Kuzmin, 1999), the Caucasian populations of the complex are sometimes also treated as a distinct species as Bufo verrucosissimus. Recent genetic studies paint a more complex picture. Firstly, based on nuclear markers, the Anatolian populations, traditionally excluded from B. b. verrucosissimus on the basis of morphology, are in fact genetically closer to this group than to B. b. bufo or B. spinosus, even if they carry B. b. bufo mtDNA (Garcia-Porta et al., 2012; Arntzen et al., 2013). Secondly, mtDNA divergence between Caucasian (B. b. verrucosissimus) and Eastern European (B. b. bufo) populations is much lower than between B. b. bufo and B. spinosus. Indeed, divergence in mtDNA and allozymes between the Caucasian and Eastern European lineages is even lower than between the subclades of B. spinosus (Garcia-Porta et al., 2012). Most importantly, based on frequencies of allozyme alleles, populations of B. b. bufo from Greece and north-western Turkey appear intermediate between Caucasian and European populations (Garcia-Porta et al., 2012) or group with Caucasian populations in nuclear trees (Recuero et al., 2012), suggesting extensive introgression between B. b. verrucosissimus and B. b. bufo in north-western Turkey and the southern Balkans (but see Arntzen et al., 2013). In our opinion, the specific status of B. b. verrucosissimus is currently insufficiently supported by the available evidence, and we maintain it as conspecific with Bufo bufo for the time being.

Stöck et al. (2006) elevated a number of mitochondrial lineages of green toads (now Bufotes) to species level (for Europe: B. variabilis and B. balearicus, in addition to B. viridis) and subsequently described a new species from Sicily based on the same lines of evidence. SBC2010 argued against accepting these species on the basis of mitochondrial DNA alone. Colliard et al. (2010) documented a contact zone in Sicily between the taxa siculus and balearicus (sensu Stöck et al., 2006) and demonstrated strong reproductive isolation between them. As these two taxa belong to the two most divergent lineages (North African and Eurasian), a two-species split of the green toad complex is clearly warranted. The Sicilian taxon siculus is closely related to the North African taxon boulengeri, which has priority over siculus. Subsequently, nuclear data were added to the picture (microsatellites – Dufresnes et al., 2018a; Gerchen, Dufresnes and Stöck, 2018, and RADseq markers – Dufresnes et al., 2019c). Although cyto-nuclear discordance was present in large areas of Europe where populations of viridis carry the variabilis mtDNA lineage, these studies confirmed that overall the previously identified mtDNA lineages correspond to distinct evolutionary units. Dufresnes et al. (2019c) also discovered that the type locality of variabilis is inhabited by the western lineage, rendering variabilis a junior synonym of viridis, and that the valid name for the Anatolian lineage is sitibundus. These two lineages (B. v. sitibundus and B. v. viridis) widely admix over a very large geographic area in Anatolia and Russia (Dufresnes et al., 2019c), suggesting that they are best treated as subspecies. The contact zone between B. v. viridis and B. v. balearicus is narrower (63 km), but still extensive if compared with other contact zones between taxa that are here treated as different species (Gerchen, Dufresnes and Stöck, 2018). In addition, raising B. v. balearicus but not B. v. sitibundus to species rank would make B. v. viridis paraphyletic (see Dufresnes et al., 2019c). The TC therefore preferred to treat B. v. sitibundus and B. v. balearicus (and the extralimital B. v. perrini) as subspecies of B. viridis.

Dufresnes et al.’s (2019c) range-wide sampling of all known taxa of the Bufotes viridis complex identified a total of eight diploid genetic clusters, including a new lineage endemic to Cyprus, which they describe as Bufotes cypriensis. Estimated to be of Messinian origin (5.3 Mya), this insular taxon is as old as or older than many species of anuran amphibians from the Western Palearctic. Yet, all ten individuals from four localities carry mtDNA haplotypes of B. v. sitibundus. Secondary contact and hybridisation with the Anatolian mainland lineage during the Pleistocene would explain this mitochondrial capture, as well as the remnants of nuclear introgression that were detected as well. In addition to this deep genomic divergence, the genome of B. cypriensis is also significantly larger than that of all other Western Palearctic Bufotes taxa. Morphologically, the Cyprus green toads are smaller than those from mainland populations, as previously reported by Stugren and Tassoula (1987). The combination of an old divergence and a larger genome size led the TC to accept the species status of B. cypriensis. Adriatic populations could represent a valid subspecies of B. viridis (for which the nomen longipes Fitzinger in Bonaparte, 1840 might be available), while green toads from Naxos (Cyclades) and Crete differ genetically from other populations and deserve genomic investigations (Dufresnes et al., 2019c). In summary, for Europe, we accept (1) Bufotes viridis, including the widespread B. v. viridis, B. v. balearicus (Italian Peninsula, Corsica, Sardinia, Sicily, Balearic islands) and B. v. sitibundus (within Europe restricted to a number of eastern Greek islands), (2) the Sicilian Bufotes boulengeri siculus and (3) Bufotes cypriensis. We note that the availability of the nomen siculus remains unclear, given that the corresponding description (Stöck et al., 2008) was only issued electronically and prior to 2011 (see Article 8.5 of the Code): whether “numerous identical and durable copies” (Article 8.1) were registered by the authors in parallel is yet to be addressed (see also Dubois et al., 2013).

Based on a high level of divergence in mitochondrial DNA sequences of Hyla tree frogs, Stöck et al. (2008) have suggested to recognise the Iberian taxon molleri and the eastern European taxon orientalis as species distinct from Hyla arborea. However, given the lack of other supporting characters (weak acoustic divergence: see Schneider, 1974; no well-supported morphological characters), SBC2010 refrained from formally accepting this systematic treatment, as it would have rested solely on mitochondrial DNA data. Several more recent studies offer a better understanding of the phylogeny of this group and of the patterns of gene flow across contact zones. Firstly, Dufresnes et al. (2015, 2016) investigated the arborea-orientalis contact zones in Poland and in the Balkans with microsatellite markers. In Poland, they found evidence of admixture over a 200 km wide zone, with mosaic contacts and interspersed hybrid populations, but with strongly restricted introgression at sex-linked loci and many populations of seemingly pure ancestry in close contact to each other (Dufresnes et al., 2016). In the Balkans, Dufresnes et al. (2015) found narrow clines (30 and 32 km of average cline width in Serbia and Greece respectively). In line with our treatment of taxa connected by unimodal hybrid zones with narrow clines, we recommend affording species status to Hyla orientalis. Secondly, the phylogenomic tree in Dufresnes et al. (2018b) unambiguously groups orientalis and molleri as sister taxa, with arborea splitting from a node basal to the molleri – orientalis divergence. Therefore, we accept molleri at species rank as well. Although the close relationships between molleri and orientalis could justify to treat them as conspecific, we refrain for the time being from this arrangement. We thus treat Hyla molleri and Hyla orientalis as valid species.

Supported by mtDNA and genomic data, two major cryptic lineages reside within Hyla intermedia (Canestrelli, Verardi and Nascetti, 2007; Stöck et al., 2008; Dufresnes et al., 2018b). They are not known to differ in any diagnostic morphological or acoustic character, even if they differ in the averages of one acoustic and some morphometric traits. The northern lineage occupies the Po Plain and adjacent regions (including Ticino in Switzerland), with the northern Apennines acting as the biogeographical barrier separating it from the southern lineage. As the name intermedia applies to the southern lineage, Dufresnes et al. (2018b, c) coined a new name, Hyla perrini, for the northern lineage. Note that, as its registration in the Official Register of Zoological Nomenclature (ZooBank) occurred later than the publication of Dufresnes et al. (2018b), the name perrini is not made available by Dufresnes et al. (2018b), but by Dufresnes et al. (2018c), who met all conditions of nomenclatural availability. Detailed analyses of the contact zone based on genomic (RADseq) data by Dufresnes et al. (2018b) revealed broad clines (96 km of average cline width) for nuclear markers and detectable admixture over approximately 130 km. Despite a relatively high cyt b distance of around 9%, and even though Dufresnes et al. (2018b) argued that the extent of the contact zone would be even larger without some form of selection against hybrids, the TC felt that the observed extent of introgression and thus the lack of strong reproductive barriers did not unambiguously allow treatment of perrini at species rank. We thus recommend to treat the northern lineage as Hyla intermedia perrini.

The authorship of the family Ranidae has been clarified by Dubois and Bour (2011), attributing it to Batsch, 1796.

Based on allozyme data (Arano, Esteban and Herrero, 1993; Veith et al., 2002, 2012), two genetically distinct groups have been recognised within Rana temporaria populations of northern Spain. The first was assigned to the subspecies R. t. parvipalmata and is restricted to the westernmost edges of the Iberian distribution (Galicia and Asturias). Frogs from western Galicia feature reduced feet webbing, smaller size and lower number of pulses per call (Vences, 1992). The second group corresponds to the nominal taxon R. t. temporaria, which extends throughout Europe. Mitochondrial data suggested a more complex picture, with four deeply differentiated lineages in the same area (Vences et al., 2013b, 2017). In a phylogeographic survey using genome-wide data, Dufresnes et al. (2020b) found one of these mitochondrial groups to be a “ghost lineage”, not differentiated in the nuclear genome. The two main lineages are strongly differentiated and are estimated to have diverged around 4 Mya. Despite the absence of geographic or ecological barriers to dispersal, they form a narrow hybrid zone (25 km) in the eastern Cantabrian Mountains. Because partial reproductive isolation is thus likely to prevent these two taxa from merging, we follow the recommendation of Dufresnes et al. (2020b) to treat R. parvipalmata as a distinct species.

Using allozymes and mtDNA, a detailed analysis of gene flow patterns across the contact zone of the northern Anatolian lineage and the Balkan lineage of the Pelophylax ridibundus – bedriagae complex in northern Greece revealed the existence of a wide hybrid zone, with introgression detectable over more than 200 km (Hotz et al., 2013). This suggests that the European and Anatolian lineages are conspecific (contra SBC2010). Since the European lineage splits from a node basal to the diversification of Anatolian lineages with respect to mtDNA according to Plötner et al. (2012), it further suggests that most lineages of this complex are conspecific, with the possible exception of the populations from Syria and Jordan (possibly the ‘true’ bedriagae, see Plötner et al., 2012). On the other hand, Plötner et al. (2010) suggested hybrid breakdown between some of these lineages, indicating incipient speciation. While undoubtedly the last word on this subject has not been written, the TC felt that it was premature to suggest taxonomic changes, especially as a large taxonomic paper based on genomic variation patterns is in preparation (G. Mazepa, pers. comm.). The same applies to the newly proposed P. cypriensis, which was found to be placed between the European and the Anatolian lineages in mtDNA, but grouped with P. cretensis (albeit with very low support) in nuclear DNA (Plötner et al., 2012). For the moment, we thus suggest no change to the taxonomy adopted in SBC2010 for European Pelophylax.

Testudines/Chelonii

Based on nuclear genomic ISSR fingerprints and mtDNA sequences, Fritz et al. (2005) described Emys trinacris as a distinct species endemic to Sicily and Calabria, albeit the record from Calabria was later questioned (Vamberger et al., 2015). A phylogenetic study using seven nuclear genes (Spinks and Shaffer, 2009) found E. orbicularis to be paraphyletic with respect to trinacris: E. o. hellenica was sister to a clade containing trinacris and the remaining lineages of E. orbicularis. This led SBC2010 to conclude that trinacris should not be recognised as a species, which has been criticised by Vamberger and Fritz (2018). While trinacris is the most basal lineage in mtDNA trees (Fritz et al., 2005, 2007), this position is weakly supported, and the level of mtDNA divergence between trinacris and the other lineages is not clearly larger than that between some lineages of E. orbicularis. A first combined analysis of genetic differentiation at eight microsatellite loci and mtDNA sequences found concordant patterns for both markers: no evidence for admixture between Sicilian pond terrapins and the remaining lineages was found, while extensive admixture was found between some other lineages of E. orbicularis (Pedall et al., 2011). Using 15 microsatellite loci and mtDNA sequences, Vamberger et al. (2015) found evidence for limited admixture between the two taxa in one Sicilian population. In addition, Vamberger et al. (2015) reported concordant clines for both markers, with cline centres matching the Strait of Messina. Vamberger et al. (2015) argue that the coincidence of the cline centres with the Strait of Messina cannot be explained by a geographic barrier effect of this narrow sea strait, because in E. orbicularis recent gene flow occurred across the Strait of Gibraltar (Velo-Antón et al., 2015), and possibly across the Adriatic Sea between southern Italy and the Balkans (Vamberger et al., 2015). In contrast, Pereira, Teixeira and Velo-Antón (2018), using seven microsatellite loci, concluded that the Strait of Gibraltar currently impedes gene flow between Iberian and North African pond turtles. However, they show that the break between the two clusters corresponds to the Central Iberian Mountains and not the sea strait. Clines of microsatellites for the trinacris – orbicularis contact zone across the Strait of Messina were inferred to be very wide (247 km) in Vamberger et al. (2015), although the significance of this estimate is hampered by a substantial (150 km) sampling gap between the two taxa. The TC takes therefore a conservative stance and treats trinacris as a subspecies of E. orbicularis, waiting for further studies resolving the complicated relationships of this complex. In this context, we note that Pöschel et al. (2018) reported a sharp transition between occidentalis and orbicularis + galloitalica in north-eastern Spain, matching that of distinct species recognised here, suggesting that the E. orbicularis complex could comprise several species. In the meantime, we recommend to maintain the Sicilian lineage as Emys orbicularis trinacris.

Squamata

The family Agamidae is sometimes credited to Fitzinger, 1826 or Gray, 1827 (see e.g. Melville and Smith, 1987). In fact the nomen was first published by Spix in 1825 as “Familia Agamae”. Even if Spix did not use the correct suffix ‘-idae’, Article 11.7.1.3 of the Code states that “a family-group name of which the family-group name suffix is incorrect is available with its original authorship and date, but with a corrected suffix”. Other conditions of availability all seem to be fulfilled in Spix (1825), who is thus the author of the nomen.

Macey et al. (2000a) sequenced a 1685-1778 bp long segment of mtDNA (including the ND1, ND2 and COI genes) to assess phylogenetic relationships of acrodont lizards. Their results suggested that the agamid genus Laudakia is paraphyletic, yet, low bootstrap support prevented definite conclusions. Subsequent studies based on mitochondrial and nuclear genes (ND2, RAG1) by Melville et al. (2009) and Edwards and Melville (2011) recovered Laudakia as monophyletic with high support. Baig et al. (2012) summarised the results of the aforementioned studies in a morphology-based revision of Laudakia. Despite failing to find distinct morphological variation within the genus, and acknowledging that Melville et al. (2009) and Edwards and Melville (2011) recovered Laudakia as monophyletic, Baig et al. (2012) partitioned Laudakia into three genera acknowledging its potential paraphyly (Macey et al., 2000a). This taxonomic act was subsequently criticised by Pyron, Burbrink and Wiens (2013), who confirmed the monophyly of Laudakia using a supermatrix approach. Within our focal area, the classification proposed by Baig et al. (2012) would affect Laudakia stellio and L. caucasia, as these authors placed the former species in the newly erected genus Stellagama, and the latter into Paralaudakia. While these genera were rapidly adopted by the wider herpetological community, we do not follow the split of Laudakia, pending substantial evidence to reject its monophyly, and therefore retain L. stellio and L. caucasia in Laudakia.

The family Chamaeleonidae is sometimes credited to Gray, 1825 (e.g. Glaw, 2015). However, Rafinesque (1815) published the name “Famille CAMÆLONIA”, based on the genus “Camæleo Daud.”, which is an incorrect subsequent spelling of the available genus Chamaeleo Laurenti, 1768. The Code is somewhat ambiguous regarding the availability of family-group nomina based on an incorrect subsequent spelling of an available genus. Article 19.1 of the Code states that an incorrect subsequent spelling is not an available name. If one follows this and Art. 11.7.1.1 (“a family-group name when first published must [$\dots$] be a noun in the nominative plural formed from the stem of an available generic name”), a family-group name based on an incorrect subsequent spelling of an available genus name is not available. Yet, the Code also states that “a family-group name is an incorrect original spelling and must be corrected if it is formed from an incorrect subsequent spelling of a generic name” (Art. 32.5.3.3) and that “a family-group name based upon [$\dots$] an incorrect spelling of the name of the type genus must be corrected” (Art. 35.4.1). It is thus clear that the Code has no intention to make a family-group name unavailable based on an incorrect spelling of the name of the type genus (see also Dubois, 2010). In conclusion, the family-group name Camaelonia is available as published by Rafinesque (1815), but its spelling needs to be corrected. The nowadays prevailing spelling Chamaeleonidae should be preserved (Art. 29.5), with its authorship attributed to Rafinesque (1815) instead of Gray (1825).

SBC2010 adopted the inclusion of Cyrtopodion kotschyi in the well-supported monophyletic genus Mediodactylus, as proposed by Macey et al. (2000b), Červenka, Frynta and Kratochvíl (2008) and Bauer et al. (2013). By enlarging the focal area of SBC2010, we hereby also include the former C. russowi, now Mediodactylus russowii. Another species occurring in the area considered by Gasc et al. (1997) but not in that of SBC2010 is the former Cyrtopodion caspium. We follow Bauer et al. (2013) in recognising the well-resolved genus Tenuidactylus and list this species as Tenuidactylus caspius. Furthermore, an introduced, well-established population of Tenuidactylus fedtschenkoi has recently been reported from the city of Odessa (Ukraine). The native range of T. fedtschenkoi lies in central Asia (western Pamiro-Altay mountains), and it was probably transported passively to Odessa (Duz’, Kukushkin and Nazarov, 2012). Not long after the record from Odessa, a revision of the genus Tenuidactylus led to the description of a new species from Uzbekistan and Turkmenistan, which was split from T. fedtschenkoi and named T. bogdanovi (Nazarov and Poyarkov, 2013). Krasylenko and Kukushkin (2017) provided an update on the status of the non-native Odessa population and assigned it to T. bogdanovi.

Within Mediodactylus kotschyi, many subspecies have traditionally been recognised. As indicated by Kasapidis et al. (2005), the genetic substructure of Mediodactylus kotschyi shows a high degree of divergence, suggesting that M. kotschyi represents a species complex. Nearly range-wide data (with limited areas in eastern and northern Anatolia excluded) of three mtDNA and three nuclear DNA fragments allowed unravelling the evolutionary history of Mediodactylus kotschyi (Kotsakiozi et al., 2018). Divergence dates back to 15 Mya, and several of the main lineages show overlapping distribution areas. Divergence in mtDNA is known to be often quite large in geckos (e.g. Nagy et al., 2012). However, distances between the main lineages are particularly large in this case (>10% 16S and >15% cyt b and COI p-distances). In addition, nuclear data groups specimens in concordance with their mtDNA lineage, and not with their geographical origin, which suggests a high level of reproductive isolation between them. The proposed splits also largely agree with morphological data (Štěpánek, 1937, 1939; Szczerbak and Golubev, 1996). The narrow contact between M. orientalis and M. danilewskii in the Western Taurus Mountains, identified by Kotsakiozi et al. (2018), corresponds to a lack of morphological intergrades (despite the narrow gap between the subspecies danilewskii and ciliciensis in the same area, see Rösler, Schmidtler and Moravec, 2012), while these new species are very close to the M. kotschyi groups defined by Beutler (1981). Five species were recognised, for all of which previously existing names are available (Kotsakiozi et al., 2018). While the delimitation of the ranges and contact zones of these new species requires further investigation (e.g. M. danilewskii and M. orientalis), we accept these species here. The following species are thus recognised in our area: M. kotschyi (mainland Balkans, most of Aegean islands, and Italy (Apulia)), M. bartoni (Crete and nearby islets), M. danilewskii (Black Sea region and south-western Anatolia), M. oertzeni (southern Dodecanese Islands), and M. orientalis (Levant, Cyprus, southern Anatolia, and south-eastern Aegean islands).

The endemic gecko from the Selvagens Islands has variously been treated as the valid species Tarentola bischoffi (e.g. Rebelo, 2008; Sindaco and Jeremčenko, 2008; Uetz, Freed and Hošek, 2019), or as a subspecies of the Canarian T. boettgeri as T. boettgeri bischoffi (e.g. Carranza et al., 2000; Pleguezuelos, Márquez and Lizana, 2002; Gübitz, Thorpe and Malhotra, 2005; Sá-Sousa et al., 2009). Its phylogenetic affinities were examined by Carranza et al. (2000, 2002) and Gübitz, Thorpe and Malhotra (2005). The genetic data available (albeit based only on mtDNA) show that the mitochondrial lineages of bischoffi are closely related to those of T. boettgeri, especially to the subspecies T. b. hierrensis from El Hierro, and are in fact nested inside the mitochondrial diversity of T. b. boettgeri from Gran Canaria, suggesting that the Selvagens Islands were recently colonised from El Hierro or Gran Canaria (Carranza et al., 2000, 2002; Gübitz, Thorpe and Malhotra, 2005). Treating bischoffi as a valid species, while retaining hierrensis as a subspecies of boettgeri (as done by the above authors who rank bischoffi as a species), is thus likely to render Tarentola boettgeri paraphyletic. The amount of mitochondrial divergence between hierrensis and bischoffi is also smaller than within the populations of T. delalandii from Tenerife or between the populations of T. angustimentalis from Fuerteventura and Lanzarote. Based on the available data, we thus recommend to treat the geckos from the Selvagens Islands as conspecific with the populations from El Hierro and Gran Canaria, as Tarentola boettgeri bischoffi.

Sánchez-Vialas et al. (2018) re-examined the description of Algyroides hidalgoi Boscá, 1916, a nomen for which the holotype has been lost, to settle its position in the synonymy of the genus Algyroides. They argued that the characters of the holotype, said to originate from the Sierra de Guadarrama and described by Boscá, fall within the morphological variability of Algyroides marchi Valverde, 1958, and designated a specimen of A. marchi as neotype of A. hidalgoi. This would make A. marchi a junior subjective synonym of A. hidalgoi. Because the conditions for automated reversal of precedence are not met (Art. 23.9.1 of the Code), A. hidalgoi would become the valid nomen of the Spanish Algyroides. Several TC members felt, however, that the interpretation of the description of Boscá (1916) by Sánchez-Vialas et al. (2018) left room for doubt, and that Boscá may not have described a specimen of Spanish Algyroides when he created the name Algyroides hidalgoi. If so, this could affect the validity of the neotype designation, respective to Art. 75.3.5 of the Code, and result in the unnecessary change of the well-established and widely used name A. marchi. Although opinions in the TC were divided about this, we recommend to maintain for the time being the use of A. marchi, in anticipation of an upcoming application to the Commission, which would maintain marchi in use until the Commission has ruled on the case.

Morphological and molecular (mtDNA and nuclear) data support the split of Psammodromus hispanicus into three distinct lineages (Fitze et al., 2011, 2012; Mendes et al., 2017). While not all areas of potential contact have been sampled (despite a recent distribution update by Molina et al., in press), the available data seem to warrant accepting these lineages as distinct species. Age estimates, lineage allopatry, the lack of mitochondrial and nuclear haplotype sharing between lineages, bioclimatic niche divergence, and the current biogeographic distribution, indicate that the three lineages correspond to three independent species. The name of the eastern species is often spelled P. edwardsianus. As shown by Crochet (2015), this is an incorrect subsequent emendation that does not meet the requirements of the Code. As a consequence, the valid spelling of the eastern species is Psammodromus edwarsianus. Thus, we add Psammodromus edwarsianus and P. occidentalis to the list of the European herpetofauna species.

A 9 Mya split marks the divergence of Timon lepidus nevadensis from the nominal subspecies T. l. lepidus (Miraldo et al., 2013). After studies on genetic (Paulo et al., 2008; Miraldo et al., 2011, 2013) and morphological differentiation (Mateo and Castroviejo, 1990; Mateo, López-Jurado and Guillaume, 1996), mtDNA and microsatellites were used to investigate gene flow patterns in a zone of secondary contact (Miraldo et al., 2013). While hybridisation and introgression were observed, gene flow was shown to be restricted. The cline width for nuclear markers was estimated at around 10 km (although with a sampling gap of around 20 km, it may actually be less). Furthermore, mostly pure populations are present on either side of the sampling gap. Considering this together with the aforementioned old genetic divergence, we accept the proposal of Miraldo et al. (2013) and treat T. nevadensis as a valid species.

Lacking range-wide sampling and adequate molecular analysis, the taxonomy of the Lacerta trilineata-pamphylica complex has remained unresolved, until mitochondrial phylogenies showed the eastern Anatolian species L. pamphylica to be nested within trilineata (Godinho et al., 2005; Ahmadzadeh et al., 2013; Sagonas et al., 2014). Remarkably, Sagonas et al. (2014) found evidence that central Aegean populations (L. t. citrovittata) are closely related to L. pamphylica. Yet, this was poorly supported across analyses and the biogeographically surprising relationship between L. t. citrovittata and L. pamphylica could reflect a methodological artefact (long branch attraction). Thus, the monophyly of L. trilineata could not be rejected. More recently, analyses of SNPs and mitochondrial sequences by Kornilios et al. (2019, 2020) found a sister-group relationship between pamphylica and eastern Aegean populations of trilineata. This led to the identification of four species-level units: L. trilineata (eastern Adriatic Coast, Greece except northeast and including Milos archipelago and Crete, south-eastern Bulgaria and North Macedonia), L. pamphylica (southern Anatolia east of Antalya), L. citrovittata (central Aegean islands, including among others Naxos, Tinos, Andros, Syros, Mykonos, Paros), and L. diplochondrodes (north-eastern Greece, Romania, Bulgaria except southeast, Turkey, eastern Aegean Greek islands). All evidence (morphology, blood biochemistry, immunoserology, congruence between highly divergent mtDNA and nuclear genomics, bioclimatic niche differences, no signs of admixture) suggests that L. pamphylica deserves species status. As the eastern Aegean populations of the complex are the sister taxon of L. pamphylica, maintaining monophyly implies also treating them as a species, L. diplochondrodes. The latter taxon does not show a lot of contact, nor signs of introgression with any of the other three clades. Concerning the population west of the Aegean Barrier, the conclusion may seem less straightforward. However, genomic analyses offer stronger support for the species status of L. citrovittata than for that of L. pamphylica. The former equally corresponds to one of the major mtDNA lineages of Kornilios et al. (2019). Given its allopatry, there is no evidence of admixture. While the (potential) contact zone between L. diplochondrodes and L. trilineata in north-eastern Greece and its wider surroundings requires more comprehensive sampling, we suggest to accept the new four species arrangement and to recognise Lacerta trilineata, L. diplochondrodes, L. citrovittata, as well as the extralimital L. pamphylica.

Using one mitochondrial and one nuclear gene, Marzahn et al. (2016) investigated the phylogeography of the Lacerta viridis complex. Four main mtDNA lineages, whose phylogenetic relationships were weakly resolved, emerged from the data: (i) Lacerta bilineata, (ii) Lacerta viridis s.s., (iii) an Adriatic and western Balkan lineage, and (iv) a newly discovered lineage from the south-eastern Balkans as well as the Turkish Black Sea Coast. A previously supposed (Amann et al., 1997) contact zone between L. bilineata and L. viridis in north-eastern Italy was found to be in fact a contact zone between the Adriatic and western Balkan lineage and L. bilineata. Another contact zone between the Adriatic and western Balkan lineage and L. viridis s.s. lies further east in Slovenia and adjacent Croatia. As a consequence, there is no known geographical contact zone between L. viridis s.s. and L. bilineata. Several other contact zones between mitochondrial lineages were identified across the distribution range. However, the nuclear data were insufficient to examine gene flow among lineages. Consequently, no species-level changes were suggested. The previously reported occurrence of L. bilineata on Cres, Croatia (Brückner et al., 2001), was confirmed. However, this record is isolated from the remaining distribution range and lies among surrounding records of the Adriatic and western Balkan lineage (Marzahn et al., 2016), suggestive of an introduced population.

Speybroeck and Crochet (2007) and SBC2010 adopted the split of the former genus Lacerta s.l., accepting all genus names recognised by Arnold, Arribas and Carranza (2007), as far as they pertained to taxa occurring within their considered area. As we have adopted a broader area definition here, we additionally formally accept the genera Anatololacerta and Phoenicolacerta. The latter only has a single representative within our area, the Cypriot P. troodica. Within our area, the genus Anatololacerta can be found on several Greek islands, including Ikaria, Samos, Rhodes, Pentanisos and Kastellorizo. Based on morphology, Eiselt and Schmidtler (1986) treated A. anatolica (including the subspecies aegaea from Samos), A. danfordi and A. oertzeni (including the subspecies A. o. pelasgiana on Rhodes, Symi and Pentanisos and the nominotypical subspecies on Ikaria) as valid species. However, because the biochemical differentiation (based on albumins) between them was deemed to be too small, Sindaco and Jermenčenko (2008) maintained all populations within Anatololacerta danfordi, following Mayer and Lutz (1989). Bellati et al. (2015) combined multi-locus species tree approaches with species delimitation methods to suggest the recognition of four distinct species in this group. Some of these species are closely related and were inferred to have diverged as recently as 500,000 years ago, i.e. a remarkably young age for speciation events within Lacertidae. Yet, there seems to be evidence of reproductive isolation between some of these species, as shown by the patterns of allele sharing in some nuclear markers. While more detailed analyses of patterns of gene flow in contact zones would be desirable, we tentatively accept the four-species taxonomy (A. anatolica, A. budaki, A. danfordi and A. pelasgiana) of Bellati et al. (2015). In our area, A. anatolica is present on Ikaria and Samos, and A. pelasgiana on Symi, Pentanisos and Rhodes. In addition, A. pelasgiana was also found (although presumed introduced in both cases) on Kasos (Kornilios and Thanou, 2016) and Kastellorizo (Kalaentzis et al., 2018), while A. budaki was found on the (nearby) islet Psomi (Kalaentzis et al., 2018).

As pointed out by Busack et al. (2016), the microfiche publication of Arribas’s (1997) thesis does not meet the criteria of publication for valid zoological nomenclature, neither under the current version of the Code nor under the previous (and then relevant) version. As a consequence, the names Iberolacerta and Darevskia were not made available in Arribas (1997). For Iberolacerta, this has no major nomenclatural consequences, as the next available nomen is Iberolacerta Arribas, 1999. However, because Darevskia Arribas, 1999 is a junior synonym of Caucasilacerta Harris, Arnold and Thomas, 1998, Busack et al. (2016) conclude that Caucasilacerta must replace Darevskia as the valid nomen for the genus of the Caucasian Rock Lizards. The conclusions drawn by Busack et al. (2016) prompted a number of responses (Arribas, 2016; Arribas et al., 2017), advocating that Caucasilacerta is a nomen nudum and hence is unavailable. Subsequently, Arribas et al. (2018) appealed to the ICZN (under Articles 78.1 and 81 of the Code) to accept Arribas (1997) as published in the sense of the Code and preserve Darevskia Arribas, 1997 and Iberolacerta Arribas, 1997. While we regard Caucasilacerta as available, we support the current application to preserve Darevskia. We note that, while the case is under consideration by the Commission, the prevailing usage of Darevskia and Iberolacerta with their authorship as Arribas, 1997 is to be maintained (Article 82).

Based on morphological variation, Stugren (1961) advocated the recognition of three subspecies of Darevskia praticola: the nominotypical subspecies in the east of the distribution (central and eastern Caucasus, northern and south-eastern Georgia, northern Armenia, southern Azerbaijan, and north-eastern Iran), the subspecies pontica in the west of the Caucasus and in western Georgia, and D. p. hungarica in Europe (north-eastern Serbia, southern Romania, north-eastern Greece, eastern and western Bulgaria). Later, he recommended to treat D. p. hungarica as a synonym of D. p. pontica, resulting in a two-subspecies classification (Stugren, 1984). On the basis of multivariate analysis of morphological, meristic and qualitative characters of Balkan and Caucasus populations, Ljubisavljevic et al. (2006) confirmed the validity of the two subspecies D. p. praticola and D. p. pontica. Tuniyev et al. (2011) presented a detailed morphological study for the populations of the Caucasian Isthmus. They confirmed two morphological clusters in the Caucasus and Transcaucasia (western Caucasus: D. p. pontica; eastern Caucasus + Transcaucasia: D. p. praticola), and described a new subspecies from the Talysh Mountains (the extralimital D. p. hyrcanica). On the basis of morphological differentiation and unpublished genetic data, they also advocated species status for D. p. pontica. Later, Freitas et al. (2016) provided a phylogeographic study of the species, based on comprehensive sampling covering most of the range (although the central and eastern Caucasus parts of the range were missing). They recovered two clades in the Caucasus and in Transcaucasia, one in the western Caucasus (corresponding with the Caucasian range of the D. p. pontica subspecies) and one in Transcaucasia (Armenia) and the Talysh Mountains, corresponding with the extralimital subspecies D. p. hyrcanica and Tuniyev’s et al. (2013) D. p. loriensis. Samples of the nominotypical subspecies were not included, although their morphology suggests that they would presumably group with the Transcaucasian samples (see Tuniyev et al., 2011, 2013). Freitas et al.’s (2016) results thus seem to support the divergence of two lineages in the Caucasus, corresponding to Caucasian populations of pontica on the one hand, and populations of the praticola phenotype (including loriensis and hyrcanica) on the other hand. However, genetic analyses of samples of praticola from the eastern Caucasus would be needed to confirm this. More surprisingly, Freitas et al. (2016) also uncovered a deep split within populations traditionally classified as pontica, with the European samples from the Balkans forming a deeply divergent lineage in both mtDNA and nuclear DNA that splits from a node basal to the clade grouping the Caucasian and Transcaucasian samples. They estimated the divergence between the European and Caucasian + Transcaucasian clades at around 2.5 Mya, with a much younger split of the Transcaucasian lineage around 650,000 year ago. As pointed out by Ljubisavljevic et al. (2006), the name D. p. hungarica (Sobolevsky, 1930), with type locality in the Transylvanian Alps (which at the time was part of the Kingdom of Hungary, including parts of today’s Romania), should be applied to the Balkan lineage. Given the incomplete geographic coverage of Freitas et al. (2016) and the somewhat borderline level of genetic divergence between the Balkans and Caucasian + Transcaucasian lineages, we refrain from recommending species status for the time being, and thus suggest to treat the Balkan populations as Darevskia praticola hungarica. We further disagree with the conclusion of Freitas et al. (2016) to treat D. p. pontica as a synonym of D. p. praticola, as all their samples correspond with the range of D. p. pontica according to Tuniyev et al. (2011), and they have therefore not analysed any sample from the range of D. p. praticola. Conclusively, we maintain the morphologically well-supported subspecies D. p. pontica and D. p. praticola for the Caucasian populations occurring in our area, while the Balkan populations are referred to as the subspecies D. p. hungarica.

Genetic relationships based on a mtDNA (cyt b) fragment suggest that Darevskia brauneri szczerbaki is sister to D. saxicola rather than grouping with other lineages of D. brauneri (Doronin, Tuniyev and Kukushkin, 2013; Tarkhnishvili et al., 2016). Based on this and on analysis of morphological variation coupled with differences in ecology, Tuniyev and Tuniyev (2012) and Doronin, Tuniyev and Kukushkin (2013) suggested to treat szczerbaki as a valid, monotypic species. However, this hypothesis is in conflict with the results of MacCulloch et al. (2000), who found a lack of fixed differences in 15 polymorphic allozyme loci between D. b. brauneri, D. b. darevskii and D. b. szczerbaki, and concluded that these three taxa are conspecific. The high incidence of hybridisation within Caucasian Darevskia makes mtDNA relationships potentially unreliable. In addition, because of the low level of cyt b divergence (2.4% between D. saxicola and D. b. szczerbaki, and 4.8-5.6% of both D. saxicola and D. b. szczerbaki towards other D. brauneri sequences) and the conflict with allozyme data, we consider this species complex to be currently too poorly studied to recognise additional species without extensive evidence from nuclear genes and/or strong morphological differentiation in sympatry or close parapatry. As both of these lines of evidence are still lacking in this case, we maintain D. b. szczerbaki at subspecies rank for the time being.

Two parthenogenetic Darevskia species which are not native to our area have been introduced near Zhytomyr, Ukraine (Nekrasova and Kostiushyn, 2016). Darevskia armeniaca occurs naturally in north-western Armenia, western Azerbaijan, southern Georgia and north-eastern Turkey, and is believed to have been introduced in 1963, whereas D. dahli, known from northern Armenia and southern Georgia, was discovered more recently (1980) within the introduced armeniaca population. A third species, D. mixta, was also introduced in 1968, but its contemporary presence could not be confirmed (Nekrasova and Kostiushyn, 2016).

Mayer et al. (2000) described the oviparous Zootoca vivipara populations of Carinthia (Austria), Slovenia, Friuli and isolated sites across the Po Plain (Italy) as the distinct and allopatric subspecies Z. v. carniolica. Additional molecular analysis confirmed its validity (Surget-Groba et al., 2001, 2002). More recently, this taxon was shown to inhabit a wider range than previously known, not only occupying parts of southern Austria, Slovenia, northern Croatia and north-eastern Italy, but actually extending west as far as the central southern Italian Alps (Cornetti et al., 2015a). Lindtke, Mayer and Böhme (2010) documented a narrow contact zone in Carinthia (Austria), and detected two natural hybrids (identified by clutch features) in a sample of 36 specimens. As they did not use genetic markers, they could not investigate the level of introgression. More recently, two studies by Cornetti et al. (2015a, b) demonstrated complete reproductive isolation between carniolica and vivipara, in spite of widespread close parapatry between these two taxa. Cornetti et al. (2015a) focused on the contact zone with local syntopy in northern Italy, and did not detect any hybrid or admixed genotype out of around 30 individuals (genotyped with 13 microsatellites). Cornetti et al. (2015b) genotyped many more individuals from several regions in the northern Italian Alps where the two taxa come in close parapatry, and found a similar lack of admixture. Thus, carniolica and vivipara appear to represent two different species, and we accept Zootoca carniolica at species level.

After being placed into the genus Lacerta, Teira dugesii and Scelarcis perspicillata were transferred to the subgenus Teira and the genus Podarcis, respectively, based on morphology (Richter, 1980). Subsequently, Teira was elevated to genus level by Mayer and Bischoff (1996). Yet, the generic allocation of S. perspicillata and T. dugesii remained a matter of confusion, with several authors attributing both species to the genus Lacerta until quite recently (e.g. Brehm et al., 2003; Perera et al., 2007). Even though Pavlicev and Mayer (2009) suggested treating Scelarcis as a junior synonym of Teira and placing both species into the genus Teira, SBC2010 adopted the genus arrangement of Arnold, Arribas and Carranza (2007) and assigned the Moroccan Rock Lizard to Scelarcis as Scelarcis perspicillata. However, a recent study using data from anchored phylogenomics and a fossil-dated time tree by Garcia-Porta et al. (2019) confirmed that Teira and Scelarcis are sister taxa and that their divergence is at a similar level or even lower than among species of many well-established genera. According to this study, Teira and Scelarcis diverged from each other in the mid-Miocene, coinciding with or even post-dating intrageneric splits in many other lacertid genera such as Algyroides, Gallotia, Iberolacerta, Lacerta, Podarcis, Psammodromus, Takydromus, and Timon. Mendes et al. (2016) argued to maintain Scelarcis mainly because of nomenclatural stability. We follow this approach and maintain Teira and Scelarcis as valid genera, awaiting additional evidence.

Psonis et al. (2017, 2018) examined species delimitation in the Podarcis tauricus group (including P. tauricus, P. milensis, P. gaigeae and P. melisellensis) using mitochondrial and nuclear DNA sequences, microsatellites and RADseq data. Their most complete phylogenomic analysis offered a fully resolved species level phylogeny, and confirmed the existence of extensive genetic structuring within P. tauricus. Two main clades correspond with the western and eastern part of the distribution of the species on either side of the Pindos Mountains. The level of divergence between them is comparable with their divergence from the well-established species P. melisellensis, P. milensis and P. gaigeae, and extensive admixture is not apparent from the available data. They differ quite obviously in coloration of adult males. Even if no information on the nature of the contact zones is available, the data at hand support the split of P. tauricus into an eastern species (retaining the name P. tauricus and including the subspecies P. t. thasopulae) and a western species, for which the oldest available name is P. ionicus (Psonis et al., 2017, 2018). Several of the subclades within P. ionicus, supported by mitochondrial and genomic data, are as divergent as other species pairs in the genus Podarcis and probably warrant species status as well, but formal recognition as separate species is still lacking. On the basis of published information, we accept the split of Podarcis tauricus into two species: P. tauricus and P. ionicus.

Using published data on three mitochondrial and three nuclear genes, Senczuk et al. (2019) examined the phylogeny of the genus Podarcis to address the systematic status of the Podarcis siculus populations from the Western Pontine Islands, off the Italian west coast. They estimated that the Western Pontine lineage diverged from all other P. siculus lineages around 4 Mya, and showed that this genetic divergence is similar to or greater than that between many other species pairs of Podarcis lizards. Hence, they formally raised the Western Pontine populations, currently classified as several subspecies of P. siculus, to species rank as Podarcis latastei, as latastei is the oldest name available for this lineage. At this stage we are reluctant to follow this decision for two reasons. Firstly, the amount of divergence between the Western Pontine populations and the rest of the P. siculus complex in Senczuk et al. (2019) is only presented as a combined mtDNA and nuclear DNA tree, not allowing to check if nuclear data independently supports this species-level divergence or not. As multiple examples of deep mtDNA divergence that are not reflected in genomic divergence are known, we feel that compelling evidence of nuclear DNA divergence is needed before adopting this new species. Secondly, Senczuk et al. (2019) presented a simplified picture of the patterns of genetic divergence in P. siculus. More detailed results by Senczuk et al. (2017, 2018) display a much more complex situation, where the Western Pontine lineage appears as one of several deeply divergent lineages in P. siculus, and latastei and siculus are not reciprocally monophyletic. While Senczuk et al. (2018) indicated differentiation in nuclear DNA between at least some of the main mtDNA lineages in P. siculus, no information on their level of reproductive isolation is yet available. As a consequence, while the TC acknowledges that P. siculus as currently understood is possibly made up of several species, one of them corresponding to the Western Pontine islands populations, we consider adopting any formal taxonomic change premature.

Michels and Bauer (2004) provided a list of what they argued to be justified emendations (citing Article 31.1.2 of the Code) of non-avian reptile and amphibian scientific names which the authors identified as inappropriate original constructions of patronyms or matronyms. Among the listed species was Podarcis raffonei (as Lacerta sicula raffonei Mertens, 1952). Because this taxon was named in honour of the collectors’ wife, Michels and Bauer (2004) concluded that raffonei should be changed into raffoneae. However, Article 31.1.2 simply states how species-group names should originally be formed. The article does not provide grounds for subsequent changes to the name. Furthermore, justified emendations can only be made to ‘spellings that must be corrected’ (Article 32.5, see also 33.2.2), in which these cases are not included. Even though Michels and Bauer (2004) are linguistically correct (Arribas, 2017), amending raffonei to raffoneae is unjustified (Article 33.2.3), making the latter an unjustified emendation and hence a junior objective synonym of the former (see also Dubois, 2007). We thus recommend to maintain the original spelling P. raffonei. As a side note, we highlight that the results of Senczuk et al. (2019) also cast serious doubts on the validity of the species status of P. raffonei, but we refrain here from advocating any change for now.

Investigating the species group comprising Podarcis cretensis, P. levendis and P. peloponnesiacus, Spilani et al. (2019) found well-supported differentiation within the latter species. Based on 17 microsatellites, the eastern populations diverged 1.86 Mya. Most noteworthy, the eastern and western lineages occur in actual or near syntopy without any apparent sign of admixture. The observed level of divergence, together with evidence of reproductive isolation, warrant a species-level split within P. peloponnesiacus. However, Spilani et al. (2019) refrain from making any taxonomic change. The TC follows this position, as we await a forthcoming morphological study, prior to proposing a formal change.

From a long line of studies on the Iberian Podarcis species, the acceptance of Podarcis liolepis and the redefinition of Podarcis hispanicus sensu stricto were the most recent steps that were adopted by SBC2010. At the time, two additional species were sufficiently substantiated, genetically as well as morphologically. Awaiting formal naming, they were listed as Podarcis hispanicus type 1 (north-western Iberian Peninsula and central Iberian mountain chains) and type 2 (parts of central and south-western Iberian Peninsula). Geniez et al. (2014) provided additional morphological analyses, and formally named them as Podarcis guadarramae (former type 1) and P. virescens (former type 2). Morphological and molecular differentiation within Podarcis guadarramae resulted in the description of the subspecies P. g. lusitanicus from northern Portugal and north-western Spain. We accept P. guadarramae and P. virescens as valid species, while the status of lusitanicus will be the focus of a forthcoming study (G. Dias and C. Pinho, pers. comm.).

Although sometimes credited to Gray, 1825 (e.g. Sindaco and Jeremčenko, 2008), the family name Scincidae must be credited to Oppel (1811), as adopted by Hedges (2014) and others. Oppel (1811) created the name as “Familia. Scincoides”. Article 11.7.3 of the Code (see family Agamidae above) makes it clear that the nomen is made available by its publication in Oppel (1811), even if the suffix must be corrected.

A split of the Scincidae into seven families would affect the systematics of the European genera, with Ablepharus being placed into Eugongylidae, Heremites into Mabuyidae and the remaining genera Chalcides, Ophiomorus and Eumeces remaining in Scincidae s.s. (Hedges and Conn, 2012; Hedges, 2014). This was neither adopted in the large-scale squamate phylogeny of Zheng and Wiens (2016), nor in the online Reptile Database (Uetz, Freed and Hošek, 2019). As most skinks are readily recognisable as belonging to this group, and the monophyly of Scincidae sensu lato is well established, we follow the argument of the ‘phenotypic diagnosability’ taxon naming criterion of Vences et al. (2013a) for the time being, keeping all species (even if there are many) within a single family. Distinction of subfamilies, however, certainly makes sense as it provides more manageable units for taxonomic revision and other purposes.

For a long time, the skink genus Mabuya included numerous species from South America, Africa and Asia. A series of phylogenetic works (e.g. Mausfeld et al., 2000, 2002; Carranza and Arnold, 2003; Mausfeld and Schmitz, 2003; Whiting et al., 2006) confirmed the monophyly of the genus, but also uncovered deep evolutionary divergence between its main radiations, which also differ consistently in several morphological and life-history traits. The initial divergence within the group is estimated to date back to the Eocene, between 40 and 50 million years ago (Karin et al., 2016). Mausfeld et al. (2002) were the first to suggest a split of the genus Mabuya to reflect the long evolutionary divergence of its main lineages, a proposal that has been universally adopted since. The Middle Eastern Mabuya species (M. aurata, M. septemtaeniata and M. vittata) form a well-supported monophyletic group in all phylogenies. They have been classified with the African species in the genus Trachylepis for several years but, even if their phylogenetic position within the radiation of the former Mabuya is still poorly resolved, they are not part of the radiation of African species in the genus Trachylepis (Karin et al., 2016). Their origin is quite ancient (estimated around the late Oligocene, more than 30 million years ago) and their clade is thus now afforded genus rank by all recent works on the subject, a position that we follow here. The valid genus-group nomen of the Middle-East clade is Heremites Gray, 1845 (masculine, see Karin et al., 2016). We thus recommend calling the Middle East species Heremites auratus, H. vittatus and the extralimital H. septemtaeniatus.

The phylogeography of Ophiomorus punctatissimus was examined by Poulakakis et al. (2008) using three mitochondrial fragments. On the basis of divergence rates of mitochondrial genes calibrated in other groups of squamates, they uncovered a deep divergence between the Asian (Anatolian) and European populations of the species, estimated to have occurred around 10 Mya. This date fits nicely with the opening of the mid-Aegean trench, estimated from geological information to have started around 12 Mya and being completed around 9 Mya. More recently, Kornilios et al. (2018) used mtDNA and nuclear DNA data (three nuclear genes) for single-locus and multilocus coalescent-based species delimitation. The established COI p-distance is substantial (12.7%). No allele sharing was found, and the Asian and European lineages appeared reciprocally monophyletic for all three nuclear genes, confirming their long-term isolation. Even if suboptimal preservation of specimens and/or morphological conservatism in these fossorial species did not allow identifying any morphological differentiation between the two allopatric Ophiomorus lineages, the authors advocated recognition of the eastern lineage from Anatolia as a new species, which they described as O. kardesi. The status of several mitochondrial lineages recovered within O. punctatissimus awaits further study. Based on the divergence time and level of genetic divergence between these two cryptic species, we accept the species status of O. kardesi. In our area, the new species occurs on the Greek island of Kastellorizo (Kornilios et al., 2018).

Phylogenetic analysis based on mitochondrial and nuclear markers (Skourtanioti et al., 2016) showed strong divergence, supporting the independent history of a clade of snake-eyed skinks (Ablepharus) from Kastellorizo and southwestern Turkey. The samples of this clade originate from an area where the only taxon known to occur according to Schmidtler (1997) is Ablepharus budaki anatolicus. As a consequence, Skourtanioti et al. (2016) suggested that the name anatolicus is available for this new species-level lineage, which splits from a more basal node than all other but one (A. pannonicus from Iran) species of the genus, and whose divergence was estimated to date back to the mid-Miocene. As the genetic differentiation and deep phylogenetic divergence of the new species was confirmed by independent analyses of both mitochondrial and nuclear genes, we agree that the genetic data strongly support the recognition of an additional Ablepharus species from SW Turkey (including Kastellorizo and hence entering our area). However, we refrain from formally accepting a new species here and prefer to wait until genetic data confirm that animals from the type locality of anatolicus indeed represent this new lineage.

Sindaco and Jeremčenko (2008), who provided the starting point of our taxonomy for areas not covered by SBC2010 or Gasc et al. (1997), follow Pasteur, Keymar and Perret (1988) in treating the Gran Canaria skinks as two species, Chalcides bistriatus in the north-east of the island and C. sexlineatus in the south-west. This classification was based on a sharp geographic transition in morphology and (especially) colour pattern between the skinks inhabiting the mesic and xeric habitats on Gran Canaria (see Brown and Thorpe, 1991a, b, although these authors rejected the hypothesis of speciation between these morphotypes). Studies on the evolutionary history of these populations using allozymes (Mayer and Tiedemann, 1991) or a combination of mtDNA and microsatellites (Suárez, Pestano and Brown, 2014) established that this differentiation has a genetic basis, originating from allopatric diversification within Gran Canaria. This divergence is linked to volcanic activity 1.5-3 Mya and is currently maintained by strong selection on coloration, in spite of considerable introgression and gene flow between the two morphs. While the deepest divergence between the mtDNA clades within Gran Canaria is dated to 1.5 Mya, the divergence between the two morphs was dated to 260,000 years ago. This discrepancy could reflect real differences between coalescence time of mtDNA lineages versus divergence time of populations, or analytical issues with one of the methods. Either way, the available data suggest a young divergence of C. s. sexlineatus and C. s. bistriatus, together with a lack of reproductive isolation. We thus recommend to treat these taxa as conspecific as C. s. sexlineatus and C. s. bistriatus, as adopted by Mayer and Tiedemann (1991), Carranza et al. (2008) and Salvador and Brown (2015).

Mitochondrial DNA data of the Canarian skinks establish with a very high support that the Chalcides from Tenerife (C. v. viridanus) and La Gomera and El Hierro (C. v. coeruleopunctatus) are not each other’s closest relative, with coeruleopunctatus being more closely related to the taxa from Gran Canaria (sexlineatus and bistriatus) than to viridanus (Brown and Pestano, 1998; Carranza et al., 2008). These relationships rule out maintaining coeruleopunctatus as a subspecies of viridanus, as was traditionally the case based on their morphological similarity. In addition, the amount of divergence between C. sexlineatus, C. viridanus and C. coeruleopunctatus is typical of interspecific divergences in the genus Chalcides (Carranza et al., 2008). We thus accept the conclusion of Carranza et al. (2008) and treat the animals from La Gomera and El Hierro as Chalcides coeruleopunctatus.

The publication dates of the works of Daudin have been worked out by Harper (1940). The volume 4 of “Histoire Naturelle des Reptiles”, containing the description of Eumeces schneiderii, was published in August 1802. The specific epithet is often spelled schneideri, even if both schneideri and schneiderii are in use. The original spelling is schneiderii (see Daudin, 1802), with schneideri as an incorrect subsequent spelling. The only reason to use this spelling rather than the original spelling would be if the incorrect subsequent spelling schneideri was in prevailing usage (see Art. 33.3.1 of the Code). Prevailing usage is defined by the Code as “that usage of the name which is adopted by at least a substantial majority of the most recent authors concerned with the relevant taxon”. We checked the number of publications using either spelling after 2000 using the electronic version of the Zoological Record and found that 17 works published after 2000 used schneiderii while 28 used schneideri. We interpret this as a lack of clear support for a prevailing usage of the incorrect subsequent spelling and thus adopt the original spelling E. schneiderii.

Considerable divergence within the genus Anguis has been revealed by means of genetic and morphological analyses (Cabela and Grillitsch, 1989; Gvoždík et al., 2010). This led to the recognition of A. graeca and A. colchica, resulting in the acceptance of at least four Anguis species in Europe by Gvoždík et al. (2010) and, subsequently, SBC2010. Although no Italian specimens were incorporated in previous analyses, Anguis fragilis was hitherto presumed to inhabit much of western, central and eastern Europe, including the Italian Peninsula (Gvoždík et al., 2010). More recently, Gvoždík et al. (2013) showed Italian Anguis to represent a deeply differentiated mtDNA clade, which presumably diverged during or shortly after the basal radiation within the genus. Genetic distances between the Italian clade and all recognised species are larger than the interspecific distances among A. fragilis, A. graeca and A. colchica. Hence, Gvoždík et al. (2013) proposed to recognise the populations from Italy and adjacent extreme south-eastern France as Anguis veronensis. Two specimens (one from NE Italy and one from Slovenia) were heterozygous for the most common A. fragilis and A. veronensis PRLR haplotypes and carried A. fragilis mtDNA, indicating hybridisation. While morphological differentiation between A. veronensis and A. fragilis is significant, the ranges of all studied characters overlap. In light of the earlier accepted splits among the European Anguis by SBC2010, the divergence during the basal radiation of the genus, and the genetic and morphological evidence presented by Gvoždík et al. (2013), we recognise the Italian and south-eastern French populations as A. veronensis.

Albert and Fernández (2009) partitioned the Iberian Worm Lizard Blanus cinereus into two species, attributing southwestern Iberian populations to the cryptic Blanus mariae and designating a lectotype for B. cinereus. Their lectotype designation was, however, found to be invalid, due to the lack of explicitly stated taxonomic purpose, while they did not establish whether the original type series consists of one holotype or several syntypes, nor examined the status of other, older nomina in the synonymy of Iberian Blanus (SBC2010). These issues were tackled by Ceríaco and Bauer (2018), who argued that the type locality of Amphisbaena cinerea Vandelli, 1797 falls within the range of populations attributed to B. mariae by Albert and Fernández (2009). To further strengthen their interpretation, they made a valid neotype designation for B. cinereus, selecting a neotype belonging to the south-western Iberian species. This effectively places B. mariae in the synonymy of B. cinereus, which becomes the valid name for the south-western Iberian Blanus species. In agreement with Sampaio et al. (2015), who confirmed that the two Iberian Blanus clades show high levels of mitochondrial differentiation and no signs of nuclear haplotype sharing, Ceríaco and Bauer (2018) accepted the existence of two Iberian Blanus species. However, they deemed no name to be valid for the Central Iberian species. Yet, two older names, Amphisbaena oxyura Wagler, 1824 and Amphisbaena rufa Hemprich, 1820, are available and relate to Blanus from Spain. The type specimen of A. oxyura is lost, while its type locality (‘Spain’, according to Wagler, 1830) makes it impossible to link this name to either of the two Spanish Blanus species. The name A. rufa was based on a holotype that is still present in the Zoological Museum in Berlin (ZMB), but the catalogue entry for this specimen shows that it originates from southern Spain, where both Blanus clades occur. As morphological identification of the two Spanish Blanus species is currently impossible, robust attribution of A. rufa to either clade requires molecular data. Yet, this is problematic with the currently available methods (Ceríaco and Bauer, 2018). Ceríaco and Bauer (2018) thus treated these two names as nomina dubia and created the new nomen Blanus vandellii. SBC2010 had already recognised the two Iberian Blanus clades at species level. We follow this arrangement, and accept that B. mariae is a junior synonym of B. cinereus, with the latter being the valid name for the southwestern Blanus clade (Ceríaco and Bauer, 2018). However, instead of introducing a new name in the form of B. vandellii, we promote the use of the oldest available name, Blanus rufus, as the valid name for the central clade until information on the identity of the A. rufa holotype can be obtained. Rather than discarding the old name until proven to apply, we advocate that when an available name exists, it should be used until proven not to apply to the relevant taxon. We thus list the two Iberian species as B. cinereus (south-western species) and B. rufus (north-eastern species).

Hedges et al. (2014) present molecular and morphological data to clarify the phylogeny of the Typhlopidae and split the large genus Typhlops into a number of well-defined new genera. As a consequence, the European blind snake species is now referred to as Xerotyphlops vermicularis. Additionally, according to Hedges et al. (2014), the non-native Flowerpot Snake, recently introduced to Italy and Spain (Zamora-Camacho, 2017; Paolino, Scotti and Grano, 2019), is now called Indotyphlops braminus.

The name of Hierophis viridiflavus has been involved in nomenclatural debate over the last few decades, but are now solved (ICZN Opinions 1463 and 1686). In 1833, Charles-Lucien Bonaparte (the nephew of Napoleon) described Coluber viridi-flavus carbonarius for the eastern Italian populations that are completely or almost completely black. The subspecies H. v. carbonarius was considered valid, until Schätti and Vanni (1986) placed it in the synonymy of the nominal form. A series of phylogeographic studies based on mtDNA and nuclear DNA confirmed that viridiflavus and carbonarius are distinct evolutionary lineages which form reciprocally monophyletic clades in mtDNA (Nagy et al., 2001; Rato et al., 2009; Mezzasalma et al., 2015; Avella, Castiglia and Senczuk, 2017). These two lineages differ in the morphology of their W chromosomes (submetacentric in the E clade and telocentric in the W clade – Mezzasalma et al., 2015). As a consequence, they have been treated as valid subspecies since Nagy et al. (2001). In 2015, Mezzasalma et al. (2015) proposed to treat H. viridiflavus and H. carbonarius as different species on the basis of (i) different morphology of the W sex chromosome, (ii) reciprocal monophyly in mtDNA with a genetic divergence of 4% in both cyt b and ND4, and (iii) morphological differentiation consistent with mtDNA differentiation. However, Rato et al. (2009) found a lack of general agreement between colour pattern and mtDNA clade in Italy, and no differences in the nuclear intron beta-fibrinogen intron 7 between the two lineages. The amount of divergence in mtDNA between H. v. carbonarius and H. v. viridiflavus is much lower than between H. gemonensis and H. viridiflavus, while the amount of divergence in PRLR between them resembles the divergence within H. gemonensis. The sample size for the chromosomes is quite low as well. The split of H. v. carbonarius from H. v. viridiflavus did not reach broad support in the TC, as several members felt the evidence is still insufficient, and they prefer to wait for information on genetic variation near the contact zones. We thus recommend to maintain Hierophis viridiflavus carbonarius as a subspecies for the time being.

Jablonski et al. (2019) applied phylogenetic and morphological analyses to range-wide sampled data, aiming to better understand the intraspecific relationships and biogeography of Elaphe sauromates, and subsequently revised its taxonomy. Known from the Balkans, Anatolia, the Caucasus, the Ponto-Caspian steppes, and the Levant, this species has been suspected to be composed of two or more genetically diverse populations (Lenk, Joger and Wink, 2001). Sequences from 63 specimens and morphological data from 95 specimens were analysed. The authors found two distinct evolutionary lineages, one of which represents a new species, Elaphe urartica. The new species is distributed in eastern Turkey, Georgia, Armenia, Azerbaijan, Nagorno-Karabakh, Iran, and Russia (Dagestan). The mtDNA genetic distances between E. sauromates and E. urartica (6-8% in COI and ND4) were interpreted as indicating a split at the Miocene-Pliocene boundary (5-8 Mya; see Kornilios et al., 2014), thus they presumably separated not very long after their common ancestors separated from E. quatuorlineata. Two out of four analysed nuclear genes were also clearly differentiated, though closely related, between E. urartica and E. sauromates, while the remaining two showed signs of incomplete lineage sorting. Both lineages are also moderately morphologically differentiated and, while none of the characters are exclusively diagnostic, their combination can be used for confident lineage identification. Conclusively, we accept Elaphe urartica as a separate species.

The ladder snake Rhinechis scalaris is characterised by a backward-oriented rostral scale that is wedged between the internasal scales. Apart from this striking feature, external morphology of R. scalaris has long been acknowledged to closely match that of Zamenis rat snakes (Salvi et al., 2018). Multiple recent phylogenetic assessments have revealed that Rhinechis (with the sole member R. scalaris) and Zamenis are closely related (Burbrink and Lawson, 2007; Pyron et al., 2011; Pyron, Burbrink and Wiens, 2013; Zheng and Wiens, 2016). Some of these studies found Zamenis to be paraphyletic in respect to Rhinechis, while others placed Rhinechis as sister to all Zamenis species, albeit with low support (reviewed by Salvi et al., 2018). The latter authors argue that this phylogenetic uncertainty reflects an evolutionary scenario in which early cladogenetic events took place at the same time or within a short time frame, making it hard to disentangle which (if any) lineage branched off first. Using two mitochondrial and five nuclear genes, Salvi et al. (2018) then inferred phylogenetic relationships between Zamenis and Rhinechis. They recovered a strongly supported clade consisting of Rhinechis scalaris and Zamenis, while the monophyly of Zamenis without scalaris remained poorly supported. As a result, these authors proposed to include scalaris in Zamenis. In agreement with the ‘clade stability’ taxon naming criterion of Vences et al. (2013a) and as a named genus of uncontroversial monophyly is obtained, we here follow this.

The California Kingsnake Lampropeltis getula californiae has been introduced to Gran Canaria, where it turned into a problematic invasive species (Monzón-Arguëllo et al., 2015; Fisher et al., 2019). Based on mtDNA data and morphological variation, Pyron and Burbrink (2009) elevated L. g. californiae and four other subspecies to species status. While the basal division in their phylogeny has L. g. getula and L. g. nigra in the one main branch and L. g. holbrooki, L. g. splendida and L. g. californiae in the other, the division between L. g. splendida and L. g. californiae is retrieved as the most recent one. Pending the publication of a multilocus analysis or a detailed study of the various contact zones, we maintain L. g. californiae as a subspecies of the Common Kingsnake Lampropeltis getula for the time being.

The groundwork of contemporary elucidation of the Natrix natrix complex was initiated by the mitochondrial phylogeography of Kindler et al. (2013), leading to rejection of Natrix megalocephala and the identification of multiple contact zones, three of which were further investigated more recently (see below). Subsequently, a virtual lack of gene flow between N. natrix helvetica and N. natrix astreptophora and the differentiation between both taxa established on multiple sources of evidence, such as microsatellites, mtDNA, osteology and external morphology, led to suggesting species status for Natrix astreptophora (Pokrant et al., 2016). Within central Europe, Kindler et al. (2017) investigated two macro-scale transects across Natrix transition zones. The eastern contact zone between two lineages identified by Kindler et al. (2013) as running from Central Europe to the southern Balkans displayed wide-reaching introgression. In contrast, the western contact zone between the traditional subspecies N. n. natrix and N. n. helvetica in western Germany was shown to be narrow (microsatellite cline width of about 40 km), with a deficit of admixed individuals generating a bimodal hybrid zone, indicative of strongly restricted gene flow. We therefore accept N. astreptophora and N. helvetica as valid species in addition to N. natrix.

Ferchaud et al. (2012) provided a well-resolved mitochondrial phylogeny of the Vipera ursinii complex, which indicates that the renardi clade, the ursinii clade and the graeca clade diverged approximately 3-4 Mya. The divergence between these three clades is of the same magnitude as between the two widely accepted species V. berus and V. seoanei. The renardi and ursinii clades do not seem to share haplotypes, although they inhabit similar habitats along the north-western Black Sea coast where Vipera ursinii moldavica occurs. Given the level of genetic divergence, lack of haplotype sharing, marked morphological divergence and lack of well supported morphological intergradation, it seems more adequate to treat V. renardi as specifically distinct from V. ursinii. Given its well-supported position at the base of a renardi + ursinii clade and although we verified a very low genetic distance between ursinii and graeca in cyt b (3.2%), this arrangement makes it necessary to treat V. graeca as a distinct species as well. Additional morphological and mtDNA and nuclear DNA data support the distinct position of the graeca clade (Mizsei et al., 2017). Several other taxa from the Caucasus and the Middle East have been put forward as valid species, two of which occur in our area: the Caucasian lotievi and the recently described shemakhensis (Tuniyev et al., 2013) from north-eastern Azerbaijan. A recent phylogenomic (RADseq data) analysis of multiple specimens of renardi and lotievi by Zinenko et al. (2016) showed a lack of genetic differentiation at the genome scale between specimens collected in the lowlands (renardi) and Caucasian uplands (lotievi). There is no genetic information for shemakhensis, which is, however, very similar to lotievi morphologically. In conclusion, we consider three European species within the Vipera ursinii complex: V. graeca, V. renardi and V. ursinii, and recommend treating V. r. lotievi and V. r. shemakhensis as conspecific with V. renardi.

Tuniyev and Ostrovskikh (2001) described Vipera orlovi and V. magnifica, two viper species from the Russian Caucasus that are related to Vipera kaznakovi. Vipera orlovi inhabits both slopes of the northwesternmost Caucasus, while V. magnifica is described from the Malaja Laba river valley and restricted to Krasnodar territory. As no molecular data was provided, and it was later shown that both taxa share mtDNA haplotypes with V. kaznakovi (Zinenko et al., 2015), further enquiry was needed. Zinenko et al. (2016) used genomic methods to demonstrate the hybrid origin of these taxa, with parapatric V. kaznakovi and V. renardi as likely parental species. Low admixture and limited genetic differentiation led these authors to treat V. magnifica as a synonym of V. kaznakovi. The authors build a case for not revoking the species status of V. orlovi by advocating caution with regards to its conservation status. While we do not reject species of hybrid origin per se, the 2016 data does not suggest reproductive isolation or strong genetic differentiation of either taxon in relation to V. kaznakovi. Thus, we do not treat V. magnifica or V. orlovi as valid species. As they are more closely related to V. kaznakovi than to V. renardi, we treat both as conspecific with V. kaznakovi. In addition, we disagree with Zinenko et al. (2016) that the Code does not allow the recognition of taxa with hybrid ancestry. The Code rules nomenclature, not systematics, and nothing in the Code precludes treating taxa of admixed ancestry as valid. As both orlovi and magnifica were described on the base of distinct phenotypic features, we tentatively maintain them as subspecies of V. kaznakovi (V. k. orlovi and V. k. magnifica) until a detailed examination of morphological variation might show them not to be morphologically distinct.

A new viper species, named Vipera walser, was described from northern Piedmont, Italy (Ghielmi et al., 2016) based on mtDNA, nuclear DNA and morphological discriminant analyses. Remarkably, while morphologically very similar to north Italian V. berus, mtDNA data showed the new taxon to be nested with geographically distant taxa of the ursinii-kaznakovi complex. For two protein-coding nuclear genes (BACH2 and RAG1), V. walser does not share haplotypes with V. berus. However, only single individuals of both species have so far been sequenced. Moreover, for RAG1, the new species is similar to V. berus, while no sequences of the ursinii complex exist for this gene. Therefore, the existence of cytonuclear discordance cannot be discarded. Until additional nuclear DNA data confirms the distinct nature of the walser population, we consider acceptance of the new species to be premature, and tentatively regard it as a population of V. berus with distinct, perhaps introgressed, mtDNA. Morphologically, V. walser does not differ much from the V. berus populations inhabiting the Italian Alps (the Italian clade of V. berus in Ursenbacher et al., 2006) but it is easily distinguishable from the Central and Northern European populations of V. berus. Thus, the Italian Alps populations of V. berus could be treated as a subspecies under the name V. b. walser. However, we refrain from making formal recommendations here, pending a detailed analysis of morphological variation between populations of V. berus from the Italian Alps (including the populations described as V. walser) and the rest of the V. berus populations.

The populations of mostly black adders inhabiting the forest-steppe zone of the south and south-eastern parts of the East European Plain have been described as Vipera nikolskii Vedmederya, Grubant and Rudaeva, 1986. The distribution and morphological characters of nikolskii compared to berus have been reviewed by Bakiev, Böhme and Joger (2005), Milto and Zinenko (2005) and Zinenko, Ţurcanu and Strugariu (2010, who showed that populations of nikolskii from the western parts of its range can be mostly composed of non-melanistic specimens). According to Milto and Zinenko (2005), several older names created by Pallas for black adders from southern Russia were based on populations resulting from intergradation between berus and nikolskii and cannot apply to the later taxon, leaving nikolskii as the valid nomen for this taxon. While it was first described at species rank, nikolskii is now variously treated as a full species (e.g. Bakiev, Böhme and Joger, 2005; Uetz, Freed and Hošek, 2019) or as a subspecies of Vipera berus (e.g. SBC2010; Zinenko, Ţurcanu and Strugariu, 2010; Mizsei et al., 2017; Crnobrnja Isailovic et al., 2019 by implication). Depending on their geographical origin, specimens of nikolskii either carry berus mtDNA haplotypes, or haplotypes grouping (within the diversity of the berus group) close to V. b. barani (Joger et al., 1997; Kalyabina-Hauf et al., 2004). A multilocus phylogeny places nikolskii within V. berus (Mizsei et al., 2017). Detailed morphological studies show extensive introgression in the contact zones with V. b. berus (Zinenko, 2004; Milto and Zinenko, 2005; Zinenko, Ţurcanu and Strugariu, 2010). We thus maintain the treatment of SBC2010 and consider nikolskii as conspecific with V. berus, supporting its recognition as V. b. nikolskii to acknowledge its morphological and ecological peculiarities.

The correct spelling of the specific epithet of the Lataste’s viper has been a matter of long lasting debates because Boscá (1878) used the spelling “Vipera Latasti” in the text and “Vipera latastei” in the caption for the accompanying plate, with both spellings in current use in the literature (see Alonso-Zarazaga, 2013 and Salvador et al., 2014 for summaries). Following an application to the International Commission on Zoological Nomenclature (ICZN) by Salvador et al. (2014), the ICZN (2017) confirmed that Vipera latastei Boscá, 1878 is the correct original spelling of the specific name.

Frétey (2019) provided compelling argumentation of why the capitalised epithet Lebetinus in Coluber Lebetinus Linnaeus, 1758 is a noun in apposition and must be treated as invariable. We agree with his interpretation, and accept that the Blunt-nosed Viper should be called Macrovipera lebetinus.

Based on morphology, Nilson and Andrén (1988) elevated Macrovipera lebetinus schweizeri to species rank. Stümpel (2012), however, found that the mtDNA haplotypes found in M. schweizeri are not limited to the Milos archipelago, but are also present near Mersin on the Turkish mainland. This author thus pointed out that treating M. schweizeri as a valid species might render M. lebetinus paraphyletic. Furthermore, they showed that in their mtDNA trees schweizeri is neither basal to the rest of the M. lebetinus haplotypes, nor highly divergent. Yet, while Stümpel’s dissertation is available, and a (brief) sentence in Stümpel and Joger (2009) refers to these results, these findings have not yet been properly published in a peer-reviewed journal, and the relevant Macrovipera sequences are not yet available in GenBank either. As a consequence, many TC members felt that a formal taxonomic decision on this case would be premature, and, while it is likely that schweizeri is best treated as a subspecies, the decision can only be taken after the evidence has been properly published, or the data has been made publicly available. Conclusively, we maintain Macrovipera schweizeri at species level for now.

The occurrence of the genus Gloydius inside the area covered by this list is unclear. The only European area where the occurrence of the genus has been reported is north of the Caspian Sea, between the Volga and Ural valleys. As explained by Conant (1982) and Dirksen and Böhme (2005), all records supported by specimens in museum collections are either on the east side of the Ural River, hence outside our area (Induski Hills = Indersky Mountains), or cannot be precisely localised (one specimen from “Gur’jev”, now Atyrau, which lies at the mouth of the Ural River on both sides of the river). Attempts to locate Gloydius west of the Ural River have failed (Conant, 1982; Bakiev, Ratnikov and Zinenko, 2007; Sarayev and Pestov, 2010; Simonov, pers. comm.). Thus, no modern records of the presence of the genus in Europe exist, and no record is supported by a collected specimen. The possible occurrence of Gloydius within Europe is based on several ancient sources that report the genus between the Volga and Ural rivers in the dry steppes or deserts east of Astrakhan (see Conant, 1982 and Bour, 1993 for details). They all seem to originate from just two original sources: Gmelin (1789), who mentions the arid deserts of Astrakhan for Coluber halys, and Pallas (1799), who, in his book devoted to his second journey to the southern areas of Russia, mentions (on p. 112) the species “Berus” and “Halys” were seen in an area called “Saltan-Murat” and located east of the Volga River, in an area of dry steppes close to Astrakhan (more precisely north-east of present-day Krasnyy Yar, see Conant, 1982 and Bour, 1993). All subsequent references are based on these two sources. It is even unclear if the mention of the deserts of Astrakhan in J.F. Gmelin’s book is based on original information he received from his uncle J.G. Gmelin, who also travelled widely in Russia including the Caspian Sea area, from Pallas himself, or from any other source. J.F. Gmelin never visited these areas himself. We may never know how reliable these old records are. However, the other venomous species mentioned by Pallas (1799) from the same area, Vipera berus, is currently absent from the dry areas between the Ural and Volga Rivers. This casts doubt on the reliability of these observations. In summary, the presence of the genus Gloydius west of the Ural River entirely rests on unsubstantiated records that cannot be verified. We thus believe the species should be formally removed from the list of European species. In addition, we note that the systematics and nomenclature of the Gloydius halys complex (for a brief review, see Wagner et al., 2016) remain problematical. One of the contentious issues is the type locality of Coluber halys Pallas 1776, which determines the valid name of the Gloydius taxon occurring close to Europe in western Kazakhstan, but this question might need to be settled by an application to the Commission.