Morphological observations were made on paratypes and populations of 11 species of Amplimerlinius, including A. amplus, A. clavicaudatus, A. globigerus, A. icarus, A. intermedius, A. macrurus, A. magnistylus, A. nectolineatus, A. paraglobigerus, A. siddiqii, and A. uramanatiensis, deposited in various international nematode collections. Results showed that A. clavicaudatus differs from other Amplimerlinius species by having four lateral incisures at the deirid level, the tail terminus has a refractive inner cuticle layer, and there is a less thickened hyaline region at the tail terminus. As the latter species shares its main morphological characteristics with Paramerlinius, it is proposed herein to transfer this species to Paramerlinius as P. clavicaudatus n. comb. (= A. clavicaudatus).
The Persian sessile nematode (Cacopaurus pestis) and pin nematodes (Paratylenchus spp.) are sedentary ectoparasitic nematodes associated with many plant species worldwide. In this study, we provide morphological and molecular characterisation of seven populations of C. pestis and eight species of Paratylenchus recovered from north-western Iran. A total of 26 new sequences of D2-D3 expansion segments of 28S rRNA and ITS rRNA were obtained and used to reconstruct phylogenetic trees. Results of phylogenetic analyses revealed that the subfamilies of Tylenchulidae form well-separated clades, but that the genera Cacopaurus and Paratylenchus (= Gracilacus) in the subfamily Paratylenchinae are clustered in one clade. It appears that the previously used character of “stylet length greater than 40 μm” is not homologous and evolved more than once within the Paratylenchinae.
Sixteen species, Amplimerlinius globigerus, A. macrurus, Bitylenchus parvus, Merlinius brevidens, M. nanus, Neodolichorhynchus phaseoli, Paramerlinius neohexagrammus, Pratylenchoides alkani, P. ritteri, P. utahensis, Scutylenchus paniculoides, S. rugosus, S. tartuensis, Scutylenchus sp. A, Trophurus impar and Tylenchorhynchus brassicae, from the families Telotylenchidae and Merliniidae were collected from different locations in Iran and molecularly characterised using sequencing of the D2D3 expansion fragments of the 28S rRNA gene. Morphometrics and light micrography for studied species are also provided as vouchers. The phylogenetic relationships of Telotylenchidae and Merliniidae with other representatives of the order Tylenchida, as obtained from Bayesian inference and Maximum likelihood analysis of partial 28S rRNA gene sequences, are presented and discussed. The results of phylogenetic analysis were in accordance with classifications in which Bitylenchus and Scutylenchus are considered as separate genera, but Tessellus and Telotylenchus were synonyms of Tylenchorhynchus. The Shimodaira-Hasegawa test of the 28S rRNA gene sequence alignment and trees rejected a large genus concept of Tylenchorhynchus and the constrained monophyly for Belonolaimidae revealed within this family two genera groups: i) Belonolaimus and Ibipora; and ii) Carphodorus and Morulaimus. The present results also support the combination of Pratylenchoides and Merliniinae into a single family, the Merliniidae.
The second population of Pratylenchoides riparius, including females and males, is described and illustrated based upon morphological, morphometric and molecular data. The present population from Iran is characterised by some differences with the type population of the species from Hungary in stylet length (24-26 vs 21-22 μm), slightly longer body (1002-1230 vs 830-960 μm), pharynx (202-211 vs 182-190 μm) and tail (64-85 vs 48-57 μm), areolated outer bands of the lateral field (vs non-areolated), widening of the lateral field near tail terminus (vs lateral incisures connecting each other) and presence of males (vs absent). The taxonomic status of the species with regarding the data from the type and presently recovered population, as well as the closely similar species is discussed. The newly recovered population was studied based upon its molecular phylogenetic charactes using the D2-D3 of 28S rRNA and the partial 18S rRNA gene sequences and the results revealed that it forms a clade with P. magnicauda in 28S, but occupies a distant placement from it in 18S phylogeny.
In this study, we provide morphological and molecular characterisation of three known species of the Criconematoidea, namely Criconema cylindraceum, Paratylenchus alleni and P. steineri, recovered from Iran. Descriptions, morphometric data, drawings and photomicrographs are provided, and comparisons are made with closely related species. Phylogenetic analysis using the D2-D3 expansion segments of the 28S rRNA gene revealed that C. cylindraceum formed a cluster with Ogma decalineatus, a species with a similar head structure, but with differences in cuticle ornamentation, tail shape and morphometric characters. Moreover, P. alleni grouped with species of Paratylenchus having four lateral lines and a short stylet (< 40 μm), exceptionally including the unresolved P. straeleni, while P. steineri formed a clade with long stylet species, including P. teres and P. wuae. The taxonomic placement of C. cylindraceum in Criconema, rather than in Criconemoides, is justified, and P. teres is molecularly differentiated from P. steineri, the two species differing in having or lacking a stylet in the fourth-stage juvenile.
Helicotylenchus ciceri n. sp. and H. scoticus are described and illustrated based on morphological, morphometric and molecular characters. The new species is characterised by a conical and truncated lip region with five or six distinct annuli, stylet 32-37 μm long with anteriorly concave knobs, secretory-excretory pore posterior to the pharyngo-intestinal valve, dorsally convex-conoid tail with a terminal projection, phasmids 14 (7-20) annuli anterior to the level of anus, empty spermatheca and absence of males. Intraspecific variation of 16 populations of H. scoticus, collected from chickpea and lentil fields in Kermanshah province, western Iran, is discussed. The results of the phylogenetic analyses based on the sequences of the partial 18S rRNA, D2-D3 expansion segments of 28S rRNA and ITS rRNA genes are provided for the studied species, confirming their differences from each other and determining the position of them and their relationships with closely related species.
The genus Pratylenchoides has recently been transferred from the family Pratylenchidae to Merliniidae. To investigate further the relationship between these ‘Pratylenchus-like’ species (residing in the subfamily Pratylenchoidinae) and the subfamily Merliniinae, more than 500 soil samples were collected from various natural and agronomic habitats in the northern and north-western provinces of Iran. In this study, paratypes or populations of 22 species of Pratylenchoides, including the Iranian populations of P. alkani, P. crenicauda, P. erzurumensis, P. laticauda, P. nevadensis, P. ritteri and an undescribed species, were studied. Intra- and interspecies variation of the following characters were investigated: position of the pharyngeal gland nuclei, shape of female and male head, striation of female tail terminus, number of lateral lines at mid-body and in phasmid region for females, presence of intestinal fasciculi, and shape of sperm. Combining morphological and molecular data prompted us to propose two clusters of related Pratylenchoides species. One cluster includes P. crenicauda, P. variabilis and P. erzurumensis, whereas the second cluster consists of P. alkani, P. nevadensis and P. ritteri. Our data point to a sister positioning of P. magnicauda vis-à-vis all Pratylenchoides species included in this research. Analyses of SSU rDNA (for family and subfamily relationships) and partial LSU rDNA sequences (for intrageneric relationships) data revealed: i) the distal and nested positioning of all Pratylenchoidinae within the Merliniidae; ii) the single transition from ectoparasitism to migratory endoparasitism within the family Merliniidae corresponds with the current subfamily partitioning; and iii) support for the monophyletic nature of the genus Pratylenchoides.