Unveiling taxonomic diversity in the deep-sea fish genus Notacanthus (Notacanthiformes: Notacanthidae) with description of Notacanthus arrontei n. sp.

Notacanthid fishes constitute a common part of benthopelagic deep-sea fish communities on seamounts and continental slopes around the world. However, their highly conserved morphology and the usual lack of information on deep-water organisms make it difficult to appropriately address their biodiversity. A multidisciplinary approach combining morphological data with a DNA-based species delimitation analyses was used to explore the taxonomy of Notacanthus species. For this purpose, morphological and molecular data were obtained from 43 individuals, and the resulting information was combined with the available data. The results showed the occurrence of Notacanthus arrontei n. sp. from the Iberian Peninsula and highlighted several taxonomic conundrums regarding the Notacanthus genus. For instance, no significant differences were found between Notacanthus indicus and the recently described Notacanthus laccadiviensis, questioning its taxonomic status. Similarly, the result of the species delimitation molecular analysis coincided with previous DNA barcoding studies supporting the snubnosed spiny eel Notacanthus chemnitzii as a species complex that requires further research. Moreover, two unidentified records from the Indian Ocean were confirmed to belong to an unknown species pending formal description, and barcoding data show for the first time the occurrence of the shortfin spiny eel Notacanthus bonaparte in the Australia-New Zealand area. This research confirms the existence of important gaps in the knowledge of notacanthid fishes and represents a step forward toward a better understanding of their biological diversity.

Gaidropsarus gallaeciae (Gadiformes: Gaidropsaridae), a New Northeast Atlantic Rockling Fish, with Commentary on the Taxonomy of the Genus.

A new species of rockling fish genus Gaidropsarus is described based on six specimens collected in Galicia and Porcupine Banks, in Atlantic European waters. An analysis of morphological characters has confirmed the specific status of specimens of a previously described clade by comparison of DNA sequences. Gaidropsarus gallaeciae sp. nov. it is distinguished from congeners by the following combination of characters: 43-44 vertebrae; 54-60 third dorsal fin rays; 44-52 anal fin rays; 21-23 pectoral fin rays; head length 21.1-25.2% of standard length (SL); length of the pelvic fin 16.2-19% SL; length of the first dorsal fin ray 15.8-27% of head length (%HL); eye diameter 15.8-20.5% HL; and interorbital space 21.7-28% HL. Using the nucleotide sequence of the 5' end of the mitochondrial COI gene as a molecular marker, the genetic p-distance between the new species and its congeners far exceeds the usual 2%, granting the former the status of an independent taxon, which is in accordance with the morphological identification. A comparison with the other 12 valid species of the genus is presented. The study also highlights the morphological diversity resulting from the meristic and biometric variability of Gaidropsarus species and lays the groundwork for future taxonomic studies on this genus.

Diversity, biogeography, evolutionary relationships, and conservation of Eastern Mediterranean freshwater mussels (Bivalvia: Unionidae).

Located at the junction between Europe, Africa, and Asia, with distinct evolutionary origins and varied ecological and geographical settings, together with a marked history of changes in orogeny and configuration of the main river basins, turned the Eastern Mediterranean into a region of high diversity and endemism of freshwater taxa. Freshwater mussels (Bivalvia, Unionidae) from the Western Palearctic have been widely studied in their European range, but little attention has been dedicated to these taxa in the Eastern Mediterranean region and their diversity and phylogeography are still poorly understood. The present study aims to resolve the diversity, biogeography, and evolutionary relationships of the Eastern Mediterranean freshwater mussels. To that end, we performed multiple field surveys, phylogenetic analyses, and a thorough taxonomic revaluation. We reassessed the systematics of all Unionidae species in the region, including newly collected specimens across Turkey, Israel, and Iran, combining COI + 16S + 28S and COI phylogenies with molecular species delineation methods. Phylogeographical patterns were characterized based on published molecular data, newly sequenced specimens, and species distribution data, as well as ancestral range estimations. We reveal that Unionidae species richness in the Eastern Mediterranean is over 70% higher than previously assumed, counting 19 species within two subfamilies, the Unioninae (14) and Gonideinae (5). We propose two new species, Anodonta seddonisp. nov. and Leguminaia anatolicasp. nov. Six additional taxa, Unio delicatusstat. rev., Unio eucirrusstat. rev., Unio huetistat. rev., Unio sesirmensisstat. rev., Unio terminalisstat. rev. removed from the synonymy of Unio tigridis, as well as Unio damascensisstat. rev. removed from the synonymy of Unio crassus, are re-described. The nominal taxa Unio rothi var. komarowi O. Boettger, 1880 and Unio armeniacus Kobelt, 1911 are proposed as new synonyms of Unio bruguierianus, and Anodonta cyrea Drouët, 1881 and Anodonta cilicica Kobelt & Rolle, 1895 as new synonyms of Anodonta anatina. Also, the presence of Unio tumidus in the Maritza River is confirmed. The phylogeographic patterns described here are interpreted concerning major past geological events. Conservation needs and implications are presented, together with populations and species conservation priorities.

Geographic range expansion of Ephippion guttifer (Tetraodontidae) in the north-eastern Atlantic.

The first record of the prickly puffer Ephippion guttifer (Tetraodontidae) from Galician waters (north-west Spain) is reported based on a male specimen of 570 mm total length (LT ) caught in the Ría de Vigo. Morphometric, meristic and DNA barcode data confirmed the identification. Histological examination of reproductive tissue was carried out in this species for the first time, showing a mature male in an actively spawning phase. A historical revision invalidates a previous record and establishes this as the northernmost confirmed capture ever reported in the north-eastern Atlantic Ocean.

Phylogenetic analysis shows the general diversification pattern of deep-sea notacanthiforms (Teleostei: Elopomorpha).

The Notacanthiformes is an ancient group of deep-sea ray-finned fishes comprising 27 species in two families; Halosauridae and Notacanthidae. Although many studies have tried to reconstruct the phylogenetic relationships among the major clades of Elopomorpha, little is known about the evolutionary history of notacanthiforms. Molecular and morphological data were used to test previous hypotheses regarding the phylogenetic relationships among notacanthiform taxa, and to unravel the origin and evolution of this group. The molecular analyses of notacanthids showed similar results to those previously obtained employing osteological data, which proposed the existence of the Lipogenyinae (Lipogenys) and Notacanthinae (Notacanthus + Polyacanthonotus) subfamilies. Nevertheless, when the external morphology data is considered Lipogenys is more related to Notacanthus than Polyacanthonotus. The analyses could not fully resolve the inner relationships of the halosaurids. The time-calibrated tree of the order Notacanthiformes shows a long process of diversification spanning from the upper Cretaceous, to 50 million years after the K-Pg extinction, with the gradual emergence of all the modern families and genera of the group. This is the first specific phylogeny of the order Notacanthiformes, combining different analyses and data in order to obtain a wider perspective of the evolution and diversification of this group of fishes.

Halosaur fishes (Notacanthiformes: Halosauridae) from Atlantic Spanish waters according to integrative taxonomy.

From 2009 to 2011 thirty-five specimens belonging to six halosaurid species of the family Halosauridae were captured in two different locations in the northern waters of Spain. The specimens were identified as belonging to the genera Halosauropsis Collett, 1896, Halosaurus Johnson, 1864 and Aldrovandia Goode & Bean, 1896, including the following species: Halosauropsis macrochir (Günther, 1878), Halosaurus ovenii Johnson, 1864, Halosaurus johnsonianus Vaillant, 1888, Aldrovandia affinis (Günther, 1877), Aldrovandia phalacra (Vaillant, 1888) and Aldrovandia oleosa Sulak, 1977. The morphometric measurements and meristic characters of these specimens are given. As a result, a new northern limit of distribution of A. oleosa from the northeastern Atlantic is reported. Using a taxonomical integrative approach, the mitochondrial DNA COI gene sequences from all individuals where determined and their comparison with morphological characters showed no incongruities. Among these specimens, the highest genetic distance within species was 0.8% while the lowest value between species was 3.3%. This ample barcoding gap has allowed the delimitation and assignment of all species reported in a way that matches the traditional taxonomical methods previously employed.

Taxonomic study of Bathygadidae fishes (Gadiformes) from Atlantic Spanish waters combining morphological and molecular approaches.

From 2009 to 2011 eleven specimens belonging to four bathygadid species of the family Bathygadidae were captured in two different locations in the northern waters of Spain. The morphometric measurements and meristic characters of these specimens are given. The specimens were identified as belonging to the genera Gadomus Regan, 1903, and Bathygadus Günther, 1878, including the following species: Gadomus dispar (Vaillant, 1888), Gadomus longifilis (Goode & Bean, 1885), Gadomus arcuatus (Goode & Bean, 1886) and Bathygadus melanobranchus Vaillant, 1888. As a result, a new northern limit of distribution of G. arcuatus from the northeastern Atlantic is reported. The first molecular identification and genetic interrelationships of Bathygadidae species, based on the mitochondrial COI nucleotide sequences -DNA barcodes- is reported. Sequences corresponding to specimens from the same species were identical and the overall mean genetic diversity (uncorrected p-distance) was 0.096 ± 0.008. Based on a morphological and meristic examination of the specimens, as well as on the available literature, an updated key of the members of the family Bathygadidae from the north-eastern Atlantic Ocean is provided.