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Gobies (Gobiidae + Oxudercidae) are among the largest groups of extant marine fishes. Fossils of gobies are abundant since the Miocene, and many species have been reported so far. However, delimitation of fossil goby species is challenging because molecular markers and diagnostic traits such as the disposition of sensory head papillae are lost. This study provides, for the first time, an actualistic framework for the identification of fossil goby species. We focus on characters that can in principle be recognized in fossils, and evaluate their ability to discriminate between extant goby species based on statistical analyses. Using 14 extant species of Gobius and seven species of Pomatoschistus, we conducted otolith morphometry, elliptic Fourier shape analysis of otoliths using the package ‘Momocs’, conventional fish morphometry, and meristic counts. In addition, the otoliths of all species are depicted based on SEM images and briefly described. Otolith Fourier shape analysis proved to be most efficient in discrimination of species within both genera, Gobius and Pomatoschistus. Several characters used in the other approaches also worked well, but the results were variable, and the relative taxonomic significance of particular variables tended to change depending on the species under consideration. We propose otolith shape analysis as a powerful tool to explore ancient goby species diversity when samples with abundant fossil otoliths are present. Overall, the herein presented data will greatly facilitate delimitation of fossil goby species in future studies, and will consequently shed new light on the evolution of goby diversity and biogeography through time.
Abstract
The gobies (Gobiidae) are the most diverse fish family in the Mediterranean Sea. Nevertheless, knowledge on their diversity, taxonomy, and phylogenetic relationships is still inadequate. The phylogenetic analyses reveal two genetically highly distinct clades among specimens identified as Zebrus zebrus. A new species, Zebrus pallaoroi sp. nov., is described based on an integrative approach. The neotype of Zebrus zebrus is designated. Genetic data confirm a pronounced level of divergence between Z. pallaoroi and Z. zebrus, with the mean genetic distance on cytochrome b being 18.1% and 1.07% on rhodopsin. Phylogenetic relationships within the Gobius-lineage were estimated on both markers. Morphologically, Z. pallaoroi is distinguished from the only congener Z. zebrus by having a snout longer than its eye, posterior nostril about 4/5–9/10 of the anterior nostril, eye diameter 4.3−4.7 in head length, ventrolateral head ridges transversally connected on the anterior side by a short transversal ridge, anterior membrane midline depth about 2/3 of the spinous ray, head canal pore α diameter about half of the distance between pore ρ and ρ 1 , suborbital sensory papillae row 5i going downwards to or near the level of row d, the distance between row 5i and row d absent or much smaller than the length of row 5i, and the body with ten to eleven vertical dark brown bands. Zebrus pallaoroi was recorded from the southern Adriatic, northern Ionian, and northern and western Aegean Seas, and is a cryptobenthic fish from very shallow waters.
Abstract
The genus Atyaephyra de Brito Capello, 1867 consists of seven species, which are distributed in Europe, Asia Minor and northern Africa. Four of them occur on the Balkan Peninsula, which is known as one of the global diversity and endemism hotspots for freshwater fauna. Atyaephyra thyamisensis Christodoulou, Antoniou, Magoulas & Koukouras, 2012 has been known from Greek mainland and is considered as endemic to the Ionian region. Herewith we report the first finding of this species from the Adriatic region, i.e., Albania and Republic of Macedonia, including the ancient Lake Prespa, and we provide new localities from Greece. Given the subtle morphological features differing this species from other congeners, we support our findings with DNA barcodes.
Abstract
To elucidate the historical biogeography of a species, the patterns of population divergence must be understood, and the evolutionary history of the species must be accurately known. For brown trout (Salmo trutta complex), estimating divergence times remains a challenge due to the lack of well-defined time calibration points and insufficient phylogeographic coverage in previous studies. The present work aims to improve molecular dating of mitochondrial control region sequences by using a multicalibration framework based on the latest paleogeological evidence for dating the origin of Lake Ohrid and two available Salmo fossils, including the overlooked Salmo immigratus. Our results clearly show that, contrary to common belief, the major divisions within the brown trout occurred in the Late Pliocene, not the Pleistocene. The Pliocene origin suggests that the brown trout lineages did not form because of geo(hydro)morphological changes during glaciation cycles but may be the result of orogeny and drainage evolution. In addition, increased sampling, particularly in Serbia, led to the identification of a new haplogroup (da-int) occupying an intermediate position with respect to da-es and da-bs haplogroups. While the control region can delineate brown trout lineages, its phylogenetic resolution is limited, so even extensive sampling could not further resolve the lineage level polytomies.