Description of two new species of tadpole-gobies (Teleostei: Gobiidae: Benthophilus)

Abstract

Benthophilus durrelli and B. ragimovi, two new species of tadpole-gobies, are described. Both belong to an assemblage of Benthophilus species with clearly differentiated dermal ossifications. B. durrelli inhabits estuarine regions, deltas, lower reaches of rivers, and dam lakes in the Sea of Azov basin and is introduced in the Volga. It was hitherto not distinguished from the Azov tadpole-goby, B. stellatus, from which it differs in the posterior position of the second dorsal fin (behind vs. in front of the anal-fin origin), comparatively small (vs. considerable) difference in size of tubercles and granules, rectangular dermal fold with slightly undulated margin (vs. triangular, with clearly undulated margin), narrow (vs. wide) first semiring-like blotch behind the first dorsal fin, and 17-21, commonly 18-20 transverse rows of neuromasts on the flanks (vs. 20-25). B. ragimovi, a deepwater species, is only recorded at western coast of middle and south Caspian from Chechen’ Island to Astara. It differs from the closest congener, B. pinchuki, in the weak (vs. well-developed) depression on the head, absence of granules in the head depression, very small, densely-set granules located on whole upper head surface and anterior part of back, sometimes also on caudal peduncle (vs. enlarged granules located only along the lateral margins of the head depression), reduced first tubercles of the dorsal row (vs. anterior dorsal tubercles of the same size as the posterior ones).

Otoliths of Caspian gobies (Teleostei: Gobiidae): Morphological diversity and phylogenetic implications

“…leobergius ). Our otolith data also question the phylogenetic integrity of the four phenotypic groups defined by Boldyrev & Bogutskaya [ 41 ]: the otoliths of the species examined here comprised four phenotypic groups based on their overall shapes, which did not show congruence to their hypothesis: group 1: B . leobergius (II); group 2: B .…”

“…Tadpole-gobies of the genus Benthophilus are a group of 21 poorly known species from the fresh and brackish waters of the Caspian and Black Sea basins, including the Sea of Azov [ 37 ]. Boldyrev and Bogutskaya [ 41 ] recognized 20 species and assigned them to four phenotypic groups (i.e., I, II, III, and IV), based on differences in size, arrangement and counts of dermal ossifications, fin ray counts, and body shape. However, the phylogenetic integrity of these groups has never been tested, since the phylogeny of the genus is poorly known and genetic data are available for only a few species [ 29 , 30 ].…”

“…However, the phylogenetic integrity of these groups has never been tested, since the phylogeny of the genus is poorly known and genetic data are available for only a few species [ 29 , 30 ]. The phylogenetic integrity of the four phenotypic groups established by Boldyrev & Bogutskaya [ 41 ] was questioned by Kovačić et al [ 37 ], since a newly described species B . persicus Kovačić, Esmaeili, Zarei, Abbasi & Schliewen, 2021 featured a mix of characters of phenotypic groups II and III.…”

“…Fish sampling was approved by the Ethic Committee of Biology Department, Shiraz University (SU-9630190). Taxonomic identifications were accomplished using available keys, primary taxonomic literature, and DNA sequence analysis [ 5 , 7 , 30 , 31 , 33 – 35 , 39 , 41 ]. The skull of each specimen was opened dorsally with a scalpel and the left sagittal otolith was extracted using fine forceps, cleaned in 5% KOH solution (~5 min), washed in distilled water (~5 min), and dried at room temperature.…”

“…The North, Middle and South Caspian Sea sub-basins harbor 21, 31, and 38 species, respectively, of which zero, three, and 10 are endemic to each [ 31 ]. Due to their low economic importance, small sizes, and distributions in difficult-to-sample deeper-water habitats [ 32 – 34 ], little is known about their biological characteristics and ecology. However, Gobiidae comprise 1/4 of species native to the Caspian Sea [ 31 ] and insights into their diversification and adaptations may help elucidate ecological and biogeographic understanding about the patterns and processes of species flock formation in the Ponto-Caspian realm.…”