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

Otoliths (ear stones) of the inner ears of teleost fishes, which develop independently from the skeleton and are functionally associated with hearing and the sense of equilibrium, have significantly contributed to contemporary understanding of teleost fish systematics and evolutionary diversity. The sagittal otolith is of particular interest, since it often possesses distinctive morphological features that differ significantly among species, and have been shown to be species- and genus-specific, making it an informative taxonomic tool for ichthyologists. The otolith morphology of the Caspian Sea gobiids has not been thoroughly studied yet, with data available for only a few species. The aim of the present paper is to examine the qualitative and quantitative taxonomic and phylogenetic information in the sagittal otoliths of these species. A total of 118 otoliths representing 30 gobiid species (including 53.5% of the Caspian gobiofauna) in three gobiid lineages (i.e., Gobius, Pomatoschistus, and Acanthogobius) and 11 genera (i.e., all Ponto-Caspian gobiid genera except Babka) were analysed at taxonomic levels using an integrated descriptive and morphometric approach. The results indicated high taxonomic efficiency of otolith morphology and morphometry at taxonomic levels for the Ponto-Caspian gobiids. Our qualitative and quantitative otolith data also (i) support the monophyly of neogobiin gobies, (ii) along with other morphological and ecological data, offer a new perspective on the systematics of Neogobius bathybius, (iii) suggest the reassignment of Hyrcanogobius bergi to the genus Knipowitschia, and (iv) question the phylogenetic integrity of the four phenotypic groups previously defined in the tadpole-goby genus Benthophilus; however, more studies are needed to complete these evaluations and confirm our otolith study findings.

A new species of Fusigobius (Teleostei: Gobiidae) from the Red Sea and Gulf of Aden.

The gobiid species, Fusigobius humerosus sp. nov., is described based on 12 type and 18 non-type specimens collected from the Red Sea and Gulf of Aden. The new species can be distinguished from congeners by a combination of meristic and morphometric characters. The new species was formerly misidentified with F. humeralis: both are characterised by a semitranslucent body; head and body with numerous small dusky orange-yellow spots; a round black spot in humeral region just above base of pectoral fin; and a black spot subequal to pupil diameter at midbase of the caudal fin. However, Fusigobius humerosus sp. nov. differs from F. humeralis by scales on side of nape not extending forward to above posterior margin of preopercle (vs. scales variably extending forward to between above posterior preopercular margin and orbit); first dorsal-fin spine longest (vs. second and third dorsal-fin spines longest); shorter upper jaw; shorter anal-fin spine; and posterior nostril about halfway between orbit and anterior nostril (vs. posterior nostril closer to orbit). The most complete description of the genus Fusigobius is provided. In phylogenetic analyses of publicly available sequences of the barcoding portion of the mitochondrial cytochrome oxidase subunit I (COI) gene, sequences derived from the new species form a separate and well-divergent monophyletic lineage. The resulting COI gene tree further suggests that the new Fusigobius species is phylogenetically most closely related to F. humeralis which forms its sister species in the maximum likelihood tree. Molecular species delimitation of available Fusigobius COI barcodes shows that 19 or 20 hypothetical divergent evolutionary lineages can be deduced depending on the analytical approach (ABGD = 19 and bPTP = 20), indicating a potentially higher taxonomic richness than the presently acknowledged 11 valid species. However, the assignment of available species names for some lineages remains uncertain, highlighting the need for an additional integrative taxonomic research on this genus.

An integrative insight into the diversity, distribution, and biogeography of the freshwater endemic clade of the Ponticola syrman group (Teleostei: Gobiidae) in the Caucasus biodiversity hotspot.

Freshwater habitats of the Caucasus biodiversity hotspot represent a center of endemism for the gobiid genus Ponticola Iljin, 1927. Hitherto, large-scale molecular studies, owing to restricted taxon and geographical sampling, have failed to give an elaborate picture of diversity and evolutionary history of these species. Here, to contribute to filling this gap, we assessed taxonomic diversity, phylogeography and evolutionary history for the south Caspian populations of Ponticola presently classified as P. iranicus and P. patimari, using an integrative taxonomic approach comprising an entire geographic range sampling, and analyses of mitochondrial DNA haplotypes, the head lateral line system, otolith shape, and meristic and morphometric variation. All freshwater samples of the P. syrman group belong to a monophyletic clade with two main subclades: a small subclade confined to the upper Sefidroud sub-basin including the type locality of P. iranicus and a large subclade with three geographically constrained haplogroups (Hg1, Hg2, and Hg3), comprising the rest of the distribution. Hg1 showed an eastern distribution including the type locality of P. patimari, while Hg2 and Hg3 are sister groups with central and western-central distributions, respectively. The freshwater clade diverged from P. syrman during the Tyurkyanian low stand (~150 m b.s.l. lasting ~0.1 Myr), while the divergence of P. iranicus and P. patimari and radiations within P. patimari took place during the Bakunian high stand (up to 50 m a.s.l. lasting ~378-480 kya). Species delimitation analyses indicated two distinct species, corresponding to each main subclade. Although the otolith shape and lateral line analyses did not reflect with phylogeographic pattern, PCA and DFA plots of meristic and morphometric data showed a clear separation of the two major subclades corresponding to P. iranicus and P. patimari, suggesting the presence of significant morphological variation meriting formal taxonomic recognition. Overall, our findings (i) reveal the presence of two freshwater endemic species in the P. syrman group, and pending further investigation, hypothesize the presence of a third cryptic species; (ii) revise and document a narrow distributional range and low diversity for P. iranicus, in contrast to a wider distributional range and high diversity for P. patimari; (iii) suggest that the climatic oscillations of the Pleistocene were associated with the cladogenesis within the P. syrman group; and (iv) allowed for the recognition of conservation units and proposition of management measures.

Identification of enigmatic Mediterranean fish Gobius ater Bellotti, 1888 (Teleostei: Gobiidae) based on morphology from underwater photographs.

Gobius ater Bellotti, 1888 is the Mediterranean gobiid species whose live appearance has remained unknown the longest since its description. A goby observed in southern France in 2021 is here identified as G. ater based on a diagnosis of morphological characters visible on high-quality underwater photographs. Then, the authors provide the first description of colouration in live G. ater and a species diagnosis based on colouration. This diagnosis allows the authors to validate a previous photographic record, also from France. Reviewing all claims of G. ater, they argue that only seven records are unambiguously valid, including the two photographic records presented here.

Gobies (Teleostei: Gobiidae) of the oldest and deepest Caspian Sea sub-basin: an evidence-based annotated checklist and a key for species identification.

An evidence-based annotated checklist of gobiid species (Teleostei: Gobiidae) inhabiting the South Caspian Sea and its catchment area (i.e., the South Caspian Sea sub-basin) is compiled. The South Caspian Sea sub-basin gobiofauna currently comprises 38 confirmed species in 11 genera (i.e., 88.4% of the Caspian gobiofauna); the most diverse genus is Benthophilus (16 species, 42.1%), followed by Ponticola (seven species, 18.4%), and Neogobius (four species, 10.5%). Ten species (26.3%) are endemic to the South Caspian Sea sub-basin, another 21 species (55.3%) are endemic in the Caspian Sea basin as a whole, six (15.8%) are native to the Ponto-Caspian region, and one species (2.6%) is exotic. According to the current IUCN Red List, 24 species (64.9%) are listed as being of "Least Concern", eight species (21.6%) are "Data Deficient", and five species (13.5%) as "Not Evaluated". Similar numbers of species are confirmed to inhabit the South Caspian Sea sub-basin waters of the three countries that border it: Iran harbors 25 species (nine genera), Azerbaijan has 28 species (10 genera), and Turkmenistan has 26 species (10 genera). The greatest known diversity of Benthophilus in South Caspian waters occurs in Azerbaijan and Turkmenistan (11 species each), whereas Iranian waters harbor seven species. In comparison, Iran, with six out of eight species (75%), has the greatest diversity of Ponticola known from the Caspian Sea basin. Species richness and endemism of the Caspian Sea gobiid-fauna varies considerably with latitude: the North, Middle and South sub-basins respectively harbor 21, 31, and 37 native species, of which 0, 3, and 10 species are endemic in that sub-basin alone. The high species diversity and endemism of Gobiidae in the South Caspian Sea sub-basin may have resulted from: (i) greater ecological diversity compared to the northern Caspian Sea marine areas (e.g., water depths) that may have led to differential niche adaptation and adaptive radiation in the Benthophilus-Anatirostrum species flock, (ii) lower historical extinction rate compared to Caspian higher latitudes, which had greater exposure to the Pleistocene's extreme climatic changes, (iii) geological history of freshwater habitats in the South Caspian Sea sub-basin that set the speciation and evolutionary stage for the genus Ponticola during these Pleistocene climatic oscillations, (iv) presently less limiting conditions compared to the North Caspian Sea, i.e., higher present winter minimum of water temperature and higher salinity, and (v) Iranian freshwater abundance, variability and habitat diversity. Contemporary gobiid diversity and endemism in the Caspian Sea basin suggests two higher-priority conservation areas: (i) freshwater habitats of the South Caspian Sea region in Iran and Azerbaijan, and (ii) shallow coastal and deep waters of the South and Middle Caspian Sea sub-basins. An identification key is provided for the updated gobiid species from the South Caspian Sea sub-basin.

A new species of tadpole-goby, Benthophilus persicus sp. nov. (Teleostei: Gobiidae) from the southern Caspian Sea.

A new gobiid species, Benthophilus persicus sp. nov., is described from the southern Caspian Sea, Iran. The new species is diagnosed by the following character states: dermal fold on cheek well-developed, large, rectangular; chin barbel 1/32/3 of eye diameter; maximum body width 15.122.9% of standard length; mouth width, 36.355.8% of head length; second dorsal fin I+78; origin of anal fin in front of vertical through origin of second dorsal fin; dermal tubercles present on body, clearly larger than granules, with two posterior rows of spinules forming an acute angle, always less than right angle; dorsal row of tubercles complete, 2229; ventral row of tubercles 2225; ventrolateral row of tubercles absent; tubercles not present on temporal and occipital head regions; granules not present on flanks; transversal suborbital row 6i below posterior end of row b; anterior interorbital transversal row pa with one or two papillae and anterior interorbital transversal papilla row pp with two or three papillae; body with 2022 transversal ltm rows starting anteriorly behind pectoral axilla and alternating anteriorly with three longitudinal llm rows.

Unravelling the taxonomy of an interstitial fish radiation: Three new species of Gouania (Teleostei: Gobiesocidae) from the Mediterranean Sea and redescriptions of G. willdenowi and G. pigra.

The clingfish (Gobiesocidae) genus Gouania Nardo, 1833 is endemic to the Mediterranean Sea and inhabits, unlike any other vertebrate species in Europe, the harsh intertidal environment of gravel beaches. Following up on a previous phylogenetic study, we revise the diversity and taxonomy of this genus by analysing a comprehensive set of morphological (meristics, morphometrics, microcomputed tomography imaging), geographical and genetic (DNA-barcoding) data. We provide descriptions of three new species, G. adriatica sp. nov., G. orientalis sp. nov. and G. hofrichteri sp. nov., as well as redescriptions of G. willdenowi (Risso, 1810) and G. pigra (Nardo, 1827) and assign neotypes for the latter two species. In addition to elucidating the complex taxonomic situation of Gouania, we discuss the potential of this enigmatic clingfish genus for further ecological, evolutionary and biodiversity studies that might unravel even more diversity in this unique Mediterranean fish radiation.

Checklist of gobies (Teleostei: Gobiidae) of the Mediterranean Sea and a key for species identification.

A checklist of 73 gobiid species (Teleostei: Gobiidae) recorded to date from the Mediterranean Sea is established following the evidence approach for checklists. The Mediterranean gobiofauna currently has 62 known native species and 11 alien species. An identification key to gobiid species known from the area is provided. The principles of character selection for the key are discussed.

A new species of Corcyrogobius (Teleostei: Gobiidae) from Île de Ngor, Senegal.

Corcyrogobius pulcher sp. nov. is described from off Île de Ngor, Dakar, Senegal. Corcyrogobius pulcher is distinguished from its two congeners by having the rear edge of the jaws ending posteriorly below mideye, second dorsal fin I/9, pectoral fin rays 17, pelvic fins oval or truncated posteriorly, scales in lateral series 26-27, anterior oculoscapular head canal with pore ß, suborbital row b of sensory papillae anteriorly beginning below vertical of posterior edge of eye, dark vertical caudal bar, branchiostegal membrane without intense dark spot, cheek with two oblique whitish stripes, the first going from the eye downwards and forward to the posterior jaws, the second on the preopercular, alternating with brown oblique stripe going from behind the eye downwards and forward across the cheek. Furthermore, mitochondrial COI-barcoding data unambiguously support the species-level distinctiveness of the three Corcyrogobius species. A key to the species of Corcyrogobius is provided.

Evidence approach to checklists: critical revision of the checklist of the Adriatic Sea fishes.

The updated checklist of Adriatic Sea fishes with a critical assessment of each species using an evidence approach is provided. Each fish species in Adriatic Sea listed in the last published checklist and those reported in published new records not included in the most recent Adriatic checklist, have been included. Of the total of 466 fish species, the presence in the Adriatic Sea was confirmed for 444 species by at least one positive record of the species in the area, the presence of 10 species is still unconfirmed, and 12 fish species are excluded from the list. An evidence approach protocol is recommended for general use for compiling checklists of marine fishes.

New species of Silhouettea (Teleostei: Gobiidae) from Qeshm Island, Iran and the DNA barcoding of the Persian Gulf and Oman Sea gobies.

Silhouettea ghazalae sp. nov. is described from Qeshm Island, Persian Gulf. Silhouettea ghazalae sp. nov. is distinguished from congeners by having: small mental fold present on chin, head length 31.4-32.4% of standard length, head width 24.5% of standard length, second dorsal fin I/11, anal fin I/13, breast with large cycloid scales, predorsal area naked, suborbital row b anteriorly beginning below anterior edge of pupil, posteriorly ending below pore ß, suborbital row c anteriorly extending more than row b and posteriorly extending less than row b, suborbital row cp oblique with four papillae, body with four ill-defined midlateral blotches and the fifth a triangular mark on the caudal fin base, no clearly defined pale saddles on back, and the first dorsal fin pigmented with dots and with dark blotch present anteriorly. A key to Silhouettea species is provided. A dataset including novel and publicly available mtDNA COI sequences of 12 species from the Persian Gulf and Oman Sea gobies belonging to eight genera have been assembled in order to provide a reference dataset for DNA barcoding studies. The new species is further characterised by a minimum K2P distance of 21% to its closest relatives in our dataset, Cabillus tongarevae in the mtDNA COI barcode region.

Cerogobius petrophilus (Perciformes: Gobiidae), a new gobiid genus and species from the Red Sea.

A new genus and species of cryptobenthic goby, Cerogobius petrophilus is described from the Red Sea based on nine specimens not exceeding 2.5 cm in total length, collected from a stone-rubble habitat at Thuwal, Saudi Arabia, at depths of 8-15 m. It was also observed underwater at the southern tip of Ras Mohammed and Marsa Alam in Egypt. Cerogobius petrophilus sp. nov. is unique among other gobies in its habitat, and in this regard it superficially resembles some species of blennies, occupying tight holes in stones covered with short algae. Molecular phylogenetic data suggest a close relationship between Cerogobius petrophilus sp. nov. and Hetereleotris, but the former differs from the latter morphologically in head shape with specific proportions of orbit and snout, forward-set position of eyes, a moderately large mouth, a long horn-like tentacle at the nostrils in the middle of snout, caudal peduncle deep and short, and in details of cephalic sensory system. A full description of the new genus and species is provided and is accompanied with osteological data that potentially can be informative in further comparisons with Hetereleotris.

Gymnesigobius medits (Teleostei: Gobiidae), a new gobiid genus and species from the western Mediterranean slope bottoms.

A new genus and species of goby, Gymnesigobius medits sp. nov., is described from the western Mediterranean slope bottoms at the Balearic Islands. The new goby belongs to the Gobius-lineage (Gobiinae). Examination of the single known specimen exhibits a unique combination of morphological characters which could not be fitted to any known genus. Gymnesigobius gen. nov. is morphologically distinguished from all other genera in the Gobius-lineage by the following combination of characters: chin without fold or barbels; mouth terminal with anterior tip above horizontal level of lower eye edge; predorsal area and first dorsal fin base naked; pelvic fin anterior membrane well developed; head with anterior oculoscapular and preopercular canals, posterior oculoscapular canal absent; pores of head canals enlarged, e.g. pores α and ρ larger or of about the same size as interspaces to pore ß; six transverse suborbital rows of sensory papillae, four continuous suborbital rows in front of row b, fifth row divided in three parts but in front of row b, sixth row just as superior part above row b and below pore α; longitudinal suborbital row b barely reaching forward to the vertical from posterior edge of eye. A full description of the new genus and species is provided. The new species, collected at a depth of between 344 and 364 m (mean depth of 354 m), is one of very few gobiid species found at bathyal depths.

Two new species of Hetereleotris (Perciformes: Gobiidae) from the Red Sea.

Two new species of the gobiid genus Hetereleotris, H. aurantiaca sp. nov. and H. semisquamata sp. nov., are described from the Red Sea, the former from Saudi Arabia at Jeddah from the cave at depth of 14-16 m, and the latter from the southern Egypt from reef flat. Hetereleotris aurantiaca sp. nov. is distinguished from its congeners by having dorsal-fin rays VI + I,10; anal-fin rays I,9; pectoral-fin rays 14, all rays branched; pelvic-fin rays I,5, the fin separated and without frenum, 5th ray unbranched; anterior nostril with a long tube without process from the rim, posterior nostril a pore with erected rim; no tentacle above eye; posterior angle of jaws extending posteriorly to below posterior edge of pupil; no opercular spine; no mental frenum; pelvic fins longer than pectoral fins; squamation reduced to a few scales on caudal peduncle at caudal-fin base; no head canals; by presence, size and pattern of suborbital rows of sensory papillae; and orange head and yellowish orange body with five faint brown bars. Hetereleotris semisquamata sp. nov. is distinctive among its congeners by unique scale pattern (scales cycloid, the squamation reduced, tapering from caudal-fin base along lateral midline towards pectoral fin where nearly reaching its base) and by coloration (head and body whitish, with brown line from eye to end of upper lip, dark brown band across interorbital area and continuing obliquely from eye to corner of opercle, broad dark brown band below first dorsal fin continuing into fin, and moderately broad dark brown bar on caudal-fin base). Furthermore, it is characterized in having dorsal-fin rays VI + I,11, anal-fin rays I,10, pectoral-fin rays 16, and absence of head canals. In addition to descriptions of two species, a key to all species of Hetereleotris is provided. Hetereleotris psammophila is reported outside the Gulf of Aqaba for the first time.

Diversification in gravel beaches: A radiation of interstitial clingfish (Gouania, Gobiesocidae) in the Mediterranean Sea.

We report a hitherto unknown radiation within the clingfishes (Gobiesocidae), discovered in one of the best-studied marine biomes, the Mediterranean Sea. The monotypic genus Gouania is a Mediterranean endemic inhabiting the interstices of gravel beaches. Using geometric morphometric analyses, we identified two distinct morphotypes (characterized by a slender and a stout body shape, respectively) among Gouania willdenowi sampled from the three major Mediterranean basins (Eastern, Western and Adriatic). Slender and stout G. willdenowi occurred sympatrically in the Adriatic and the Eastern Mediterranean basins. Only the stout morphotype was found in the Western Mediterranean. Morphotypes were further distinguished by relative eye size and number of vertebrae. Based on mitochondrial and nuclear gene sequences, five highly divergent clades (COI-based K2P distances of 8 to 15%) were identified. The clades represented, respectively, stout Adriatic, slender Adriatic, stout Eastern, slender Eastern and stout Western Mediterranean Gouania. This suggests that the genus Gouania comprises at least five different species. Phylogenetic relationships among clades furthermore imply repeated evolution of convergent morphotypes. The onset of the Gouania radiation was dated to 3.23 (95% HPD 2.08-5.90) mya, and may therefore have overlapped with or followed the Messinian salinity crisis.

Lebetus patzneri (Teleostei: Gobiidae), a new goby species from the Balearic Islands, western Mediterranean, with first records of Lebetus guilleti (Le Danois, 1913) from this area and Norway, and with notes on its biology.

A new goby species, Lebetus patzneri sp. nov. (Teleostei: Gobiidae) is described based on two preserved and two photographed specimens collected from two circalittoral bottom locations off the Balearic Islands, western Mediterranean. It differs from the one or both other Lebetus species by each of following characters: P 15-16; D2 segmented fin rays 7-8; snout slightly larger than eye diameter; eyes small, 23.3-25.5% of head length; body height low, body depth at pelvic fin 14.9-16.4%; lips thick, giving mouth a broad, almost rectangular shape in dorsal and lateral view; minute black "pepper" spots on predorsal area, dorsum, flanks and caudal peduncle, visible in fresh and preserved specimens; the most of the caudal peduncle similarly colored as the lateral area below D2, reddish or brown. We further report first records of Lebetus guilleti (Le Danois, 1913) from Norway and the Balearic Islands, and observations of its conspicuous courtship behavior ("D1 waving"), and coloration including the first description of its red fluorescence pattern.

Didogobius janetarum sp. nov., a new cryptobenthic goby species from the Cape Verde Islands (Teleostei: Gobiidae).

Didogobius janetarum sp. nov. is described from five specimens collected from small caves and rock crevices between 12 and 20 m depth off two locations of Santiago Island, Cape Verde Islands. The species differs from all currently described congeners by the combination of the following characters: (1) 27 vertebrae, (2) second dorsal fin I + 10, (3) posterior quarter of predorsal region in front of first dorsal fin origin scaled, with several rows of cycloid scales, (4) body squamation cycloid anteriorly and ctenoid posteriorly, (5) scales in the lateral series 30-32, (6) anterior oculoscapular canal present, (7) preopercular head canal absent, (8) suborbital row 7 each a single papilla, (9) suborbital rows 2 and 4 close to orbit, and by (10) branchiostegal membranes uniformely black below preopercle, forming a V-shaped mark. Definitions for all used meristic counts are presented to serve as a reference for gobioid meristic studies. The genus is rediagnosed to accommodate recently described Didogobius species.

Redescription of the genus Koumansetta (Teleostei: Gobiidae), with description of a new species from the Red Sea.

The gobiid genus Koumansetta Whitley, placed in synonymy by some authors with the similar genus Amblygobius Bleeker, is redescribed and its validity based on an integrated morphological and molecular assessment is confirmed. The following characters have been found that distinguish Koumansetta from any of 15 recognized valid species of Amblygobius: oculoscapular transverse rows trp and tra long, extending dorsally well above level of rows x1 and x2; snout pointed, prominent, longer than eye diameter, with gently sloping dorsal profile, overhanging mouth; mouth subterminal; the upper limb of first gill arch with 1-2 slender, weak and soft gill rakers anteriorly, followed by 1-5 short, also soft, broad structures; first two dorsal-fin spines elongate, remaining spines progressively shorter; pelvic frenum absent; body brown to brown-green in upper and lateral sides with narrow yellow or orange longitudinal stripes on body and head, black ocellated spot on the second dorsal fin, and another black spot dorsoposteriorly on caudal peduncle. The following three species are assigned to Koumansetta: K. rainfordi Whitley, the type species of the genus, known from the western Pacific Ocean; K. hectori (Smith), the most widespread species, known from islands of the western Indian Ocean to Micronesia and Fiji; and a new species, restricted to the Red Sea and the inner Gulf of Aden. Koumansetta hoesei sp. nov. has formerly been confused with similar K. hectori, but differs in various details of coloration, and in some morphological characters. Moreover, K. hoesei sp. nov. is evolutionary well divergent from K. rainfordi and K. hectori, its closest relative, as shown by phylogenetic analysis of the mitochondrial COI barcoding region. In addition to the description of the new species, brief species accounts are provided for K. hectori and K. rainfordi, and a key to the three species.

A new species of Buenia (Perciformes: Gobiidae) from the western Mediterranean slope bottoms, the redescription of Buenia jeffreysi and the first Balearic record of Buenia affinis.

A new gobiid species, Buenia lombartei sp. nov. (Teleostei: Gobiidae) is described from the continental slope off the Balearic Islands, western Mediterranean. The Atlantic species Buenia jeffreysii (Günther, 1867) is redescribed and the first record of Buenia affinis Iljin, 1930 is reported for the islands. A key for the species of genus Buenia is provided. The new species can be distinguished from congeneric species by morphological characters: anterior oculoscapular canal semi-closed with pores σ, λ, κ, α, ρ and additional pores and open furrows; suborbital row c of 6 papillae; anal fin I/7-I/8; scales in lateral series 25-27; scales in transverse series 6; pectoral fin rays 18; the second spine of the first dorsal fin longest, backwards reaching to middle second dorsal fin in males when folded down; pelvic fin anterior membrane reduced to less than one sixth of spinous ray in midline depth; tongue well developed and bilobed and several morphometric characters. The new species is also characterized by its reduced colouration and unique depth range and occurrence on upper slope muddy bottoms. Contrary to this, only a small number of gobiid species in the Mediterranean reach beyond the circalittoral to the deep shelf, and just a few have records below the shelf break. Phylogenetic analysis of their mitochondrial COI sequence grouped the two specimens within the same clade as B. jeffreysii, but one apomorphic transversion diagnoses the B. lombartei subclade. A hypothesis about rapid speciation of B. lombartei as well as alternative hypotheses are discussed. During the Last Glacial Maximum, boreal fish species such as cold-water adapted gadids, now restricted to northwestern Europe, entered the Mediterranean. This may have also been the case of the boreal population of B. jeffreysii. At the end of the glacial period, increasingly warming Mediterranean waters might restricted B. jeffreysii to deeper coldwater mud habitats of the upper slope, where it finally adapted to bathyal conditions.