Dorsal-fin Origin Research Articles

Glyptothorax pongoensis, a new species of rheophilic catfish (Sisoridae) from the Brahmaputra River drainage, Nagaland, India

ABSTRACT Glyptothorax pongoensis, sp. n. is described from the Yongmon River in Nagaland, India. The new species can be distinguished from its congeners in the Indian subcontinent by the following combination of characters: an ovate-shaped thoracic adhesive apparatus with skin ridges present over the entire apparatus, including the subulate-shaped median depression; presence of plicae on the ventral surface of the pectoral fin spine and the first ray of the pelvic fin; W-shaped anterior nuchal plate element; dorsal-fin origin nearer to the snout tip than to the origin of the adipose fin; posterior margin of dorsal spine rugose with 4–5 ridges, tuberculate skin, and nasal barbel not reaching eye when adpressed. http://www.zoobank.org/urn:lsid:zoobank.org:pub:5D71008D-5D28-4C77-9FA2-D5074DDA7BC9

A new species of the Cambeva variegata group (Siluriformes: Trichomycteridae) from the Serra do Espinhaço, south-eastern Brazil, under severe risk of extinction

The mountain ranges of southeastern and southern Brazil are inhabited by a great diversity of catfishes of the genus Cambeva. The Cambeva variegata group, diagnosed by having a prominent skin crest similar to an adipose fin, an interrupted supraorbital laterosensory canal, with an additional supraorbital S4 pore, and a relatively small premaxilla with an accentuated constriction on its lateral portion, occurs in a broad area of south-eastern Brazil, mostly within the savannah-like Cerrado vegetation at the northern-most part of the genus distribution. The new species described here was collected in streams of the Rio das Velhas drainage, Rio São Francisco basin, draining the Serra do Espinhaço. The new species is diagnosed by having more interopercular odontodes and a combination of morphometric data, colour pattern, relative dorsal-fin origin and vertebra position, and-fin-ray morphology. Field studies indicate that the two localities where the new species occur are being dramatically affected by negative human impacts, putting it in severe risk of extinction.

Schistura sonarengaensis, a new species of cave-dwelling loach (Teleostei: Nemacheilidae) from Meghalaya, northeast India.

A new species of nemacheilid loach, Schistura sonarengaensis sp. nov., is described from three cave-dwelling populations (Barak-Surma-Meghna drainage) in the South Garo Hills district of Meghalaya, India. The new species possesses prominent eyes but is easily distinguished from all the congeners of the genus Schistura from Barak-Surma-Meghna and adjacent rivers drainages of northeast Indian (except S. syngkai) in having 13-26 vertically elongated to circular mid-lateral black blotches (brownish in life) overlayered on a grayish-black mid-lateral stripe on a dull white or pale-beige (golden brown in life) body. However, it can be easily distinguished from S. syngkai in having a complete (vs. incomplete) lateral line with more 72-89 (vs. 19-42) lateral-line pored scales, greater pre-dorsal length (48.5-53.1 vs. 41.9-44.1 %SL), a wider body at dorsal-fin origin (11.3-16.7 vs. 9.4-10.3 %SL), greater dorsal (18.1-21.1 vs. 15.1-17.0 %SL) and lateral (20.9-24.1 vs. 17.4-18.9 %SL) head length, a wider head (14.5-18.5 vs. 11.6-13.3 %SL), and moderately forked (vs. emarginated) caudal fin. Further, molecular analysis confirms the distinctiveness of S. sonarengaensis sp. nov. from its congeners found in northeast India by significant divergences with uncorrected genetic distance ranging from 3.7% to 17.3% in the mitochondrial cytochrome c oxidase subunit I (COI) gene dataset. The phylogenetic position of the new species with its sister species was evaluated using maximum likelihood and Bayesian analysis. The species delimitation approaches assemble species by automatic partitioning (ASAP) and Poisson tree processes (PTP) utilized for testing species assignments consistently identified our test group as a distinct species from its sister species. Although the new species lacks typical morphological adaptations usually associated with a subterranean life, such as complete absence (or vestigial presence) of eyes and pigmentation, it exhibits a reduction of pigmentation when compared to the epigean congeners.

A new species of short unpatterned moray eel (Anguilliformes: Muraenidae) from the northwestern Indian Ocean, including the Socotra Archipelago, with a redescription of Gymnothorax pseudoherrei Böhlke

A new species of short brown unpatterned moray eel, Gymnothorax. arabicus sp. nov., is described based on specimens collected from the northwestern Indian Ocean, including the Red Sea, Socotra Archipelago, and Arabian Gulf. The new species is characterized by having the dorsal-fin origin before the gill opening, two branchial pores, one or two median intermaxillary teeth, biserial maxillary teeth, total vertebrae 114–120, and a plain brown head and body with dark yellow color at the tip of the tail. The new species formerly has been confused with G. pseudoherrei but is distinguished from it by having slightly more total vertebrae (114–120 vs. 111–116), dark stripes on the throat and side of the head, and a larger maximum size (ca. 300 mm TL vs. ca. 200 mm TL). Gymnothorax pseudoherrei, currently known from the Maldives and Sri Lanka to the Philippines, Solomon Islands, and northern Australia, is redescribed in the present study. A comparison of the COI mtDNA in BOLD, in association with published phylogenetic evidence, confirms that G. arabicus and G. pseudoherrei form two separate genetic lineages, corroborating the morphological data.

Cobitis feroniae, a new spined loach from southern Latium, Italy (Teleostei: Cobitidae)

Cobitis feroniae, new species, is described from central Italy. It is distinguished from C. zanandreai, its putatively closest relative, by having several, small, black dots below Z4; minute, black spot at the upper caudal peduncle, and the pigmentation in Z2 separated from pigmentation in Z1 anterior to the dorsal-fin origin. It is further distinguished from C. zanandreai by having 13 diagnostic nucleotide substitutions in the mtDNA COI barcode region, and a K2P nearest–neighbour distance of 2.9%.

Oxynoemacheilus fatmae, a new species from the Güzelhisar Stream in the Aegean Sea basin, Türkiye (Teleostei: Nemacheilidae).

Oxynoemacheilus fatmae, a new species, is found in the Güzelhisar Stream in the northern Aegean Sea basin. It is differentiated from all other species of Oxynoemacheilus in the northern Aegean Sea and adjacent basins by having four to eight irregularly shaped narrow black bars on the posterior part of flank, and anterior parts of the flank with a marbled pattern. O. fatmae is differentiated from the closest species Oxynoemacheilus theophilii by having 14 fixed diagnostic nucleotide substitution sites, and the pair-wise genetic distance is 2.22%. It further differs from O. theophilii by having a slenderer body (body at dorsal-fin origin: 15%-17% standard length [SL] vs. 17%-18%), a slenderer caudal peduncle (10%-12% SL vs. 12%-13%), a more forked caudal fin (length of middle caudal-fin lope: 16%-19% SL vs. 19%-23%), and the absence the dorsal and ventral adipose crests on the caudal peduncle behind the vertical of the posterior anal-fin base (vs. present). Three species delimitation tests (assemble species by automatic partitioning (ASAP), automatic barcode gap discovery (ABGD) and generalized mixed yule-coalescent (GMYC)) and phylogenetic analyses reinforce the validity of O. fatmae as a distinct species.

An integrative taxonomic study on needlefishes (Belonidae) unveils two new species within the genus Ablennes from the Indian Ocean

The needlefish genus Ablennes remains monotypic, characterized by the globally distributed flat needlefish known as Ablennes hians. Their taxonomy has been mired with ambiguities due to the greater-than-average morphological variations observed in samples from different regions. Utilizing integrated taxonomic methods relying on mitochondrial molecular markers, it was revealed that the species initially perceived as a single entity is, in fact, a complex comprising at least three different species. In this context, we introduce two new species: Ablennes joseberchmansis sp. nov. and Ablennes gracalii sp. nov., They are morphologically distinct: in view of the morphometry and meristic characteristics. A. joseberchmansis sp. nov. and A. gracalii sp. nov. display distinct differentiation characteristics from A. hians in terms of dorsal fin, nostril position, dorsal fin origin, vertebrae count, scale counts, head length, eye diameter, interorbital width, maxilla length, dorsal ray height, depth at pelvic origin, lower lobe of the caudal fin, and caudal peduncle depthcaudal peduncle depth. These variations highlight their unique morphological traits and aid in their differentiation within the genus Ablennes. We assessed genetic relationships using a Maximum likelihood (ML) phylogenetic tree, revealing three distinct clades of morphological differences in Ablennes specimens from different morphological groups. The genetic variation, as represented by Kimura 2 parameter (K2P) distances, within the three Ablennes species spans from 6.5% to 9.4%. More specifically, we observed a 7.5% genetic difference between A. hians and A. joseberchmansis sp. nov., and a 6.5% distinction between A. hians and A. gracalii sp. nov. The interspecies divergence between the two newly identified species measured at 9.4%. These findings, which showcase the genetic distinctions among the three morphologically distinct Ablennes specimens, provide strong confirmation for the existence of three separate species within the Ablennes genus of needlefish in the Indian Ocean.

Is Garra rezai (Teleostei, Cyprinidae) a species known only from two widely disjunct areas in the Tigris drainage?

Garra rezai was recently described from two geographically distant areas in the Tigris drainage: upper Yanarsu River (eastern Türkiye) and Bouein-Sofla Creek (Iran). In the scope of this study, we aimed to ascertain the distribution ranges of G. rezai and its morphologically most similar congener G. rufa in Türkiye by examining 1165 specimens from 73 lots, which were collected between 1957 and 2023 and currently curated in two broad fish collections. To achieve this, we focused on two important diagnostic morphological characters which distinguish these two species: scales on predorsal mid-line between dorsal-fin origin and nape, and branched dorsal-fin rays. The results revealed that G. rufa is a widely distributed species in the Tigris-Euphrates catchment, while G. rezai is regionally widespread, with populations identified in at least six different regions within the Tigris catchment. Additionally, G. rezai is documented for the first time in the upper Euphrates. Furthermore, we identified the drainage areas where G. rezai co-exists with G. rufa.

A new species of Yunnanilus (Cypriniformes: Nemacheilidae) from upper Pearl River, Yunnan, China

A new species (Cypriniformes: Nemacheilidae) Yunnanilus yangi sp. nov. was described from Upper Pearl River (Nanpan Jiang) in Mile County, Honghe Hani and Yi ethnic Autonomous Prefecture, Yunnan Province, China. Yunnanilus yangi sp. nov. can be distinguished from other species within the genus by the following characteristics: (1) upper lip with median incision; (2) upper jaw without processus dentiformis; (3) dorsal-fin origin closer to snout tip base than to caudal-fin base; (4) pelvic-fin rays i, 6-7; (5) branched caudal-fin rays 16 (vs. 14-16). According to morphological comparison, Yunnanilus yangi sp. nov. can be distinguished clearly from all the other species in the Yunnanilus. In addition to the morphological characteristics, phylogenetic analysis of the mitochondrial cytochrome b further confirmed that Yunnanilus yangi sp. nov. is a member of Yunnanilus. Furthermore, the least genetic distance between Yunnanilus yangi sp. nov. and other species of Yunnanilus in cytochrome b gene reached 6.33%.

Redescription of Cyprinion muscatense (Teleostei: Cyprinidae) with the first phylogenetic analysis of the genus.

Members of the genus Cyprinion (Cypriniformes: Cyprinidae) are found in the Indus River basin west to the Arabian Peninsula and the Tigris-Euphrates River drainages (Persian Gulf basin). The taxonomic status of Cyprinion including Cyprinion muscatense is poorly understood when compared to other cyprinid genera. C. muscatense has been considered as a member of the Cyprinion watsoni-microphthalmum group and a valid species endemic to the Arabian Peninsula. Here, we redescribe C. muscatense based on an integrative morphological and molecular approach and freshly sampled material from several localities in the Oman Mountains ecoregion. The results showed that C. muscatense is distinguished from the other Cyprinion species in the Arabian Peninsula by having a short, thin, and slightly serrated last unbranched dorsal fin ray; the lower number of circumpeduncular scales; lateral line scales; and also scales between the lateral line and the dorsal-fin origin. Subterminal mouth, presence of one pair of small barbels at the mouth corner, 3-4 unbranched and 9½-10½ dorsal-fin branched rays, 12-14 pectoral-fin rays, 7-8 pelvic-fin rays, 2-3 unbranched and 6½-7½ branched anal-fin rays, and 37-40 lateral line scales are other morphological characteristics of C. muscatense. C. muscatense is also well distinguished by molecular characters among its congeners. The first molecular phylogenetic analysis of the genus, covering all currently recognized Cyprinion species except for C. watsoni, is also presented. C. muscatense is resolved as the sister species to another endemic fish of the Arabian Peninsula Cyprinion mhalense, with a Kimura-2-Parameter model distance of 5.3%.

Opsarius siangi, a new Chedrinae fish species from the Brahmaputra drainage, India

Opsarius siangi sp. nov., a previously undocumented species, has been identified from Siang River, Pasighat, Arunachal Pradesh, India. This newly described species is distinguished by a suite of unique morphological characteristics, notably including a complete lateral line, consisting of 65–77 scales, 32–39 pre-dorsal scales, 12–15 scales positioned between dorsal fin origin and lateral line, presence of two pairs of barbels, body depth ranging from 18.80% to 27.42% of standard length and a distinct pattern of 8–15 vertical bars adorning the body. A comprehensive genetic analysis was conducted by scrutinizing 78 Cytochrome oxidase I (COI) sequences extracted from Chedrinae fishes, with particular focus on Opsarius and Barilius genera. Phylogenetic analysis revealed that O. siangi sp. nov. occupies a distinctive clade, displaying close affinity with O. shacra. Intraspecific K2P genetic divergence, assessed at 0.02, falls well within established species delineation thresholds, while interspecific divergence in comparison to O. shacra was recorded at 0.112. Complementary species delimitation methodologies, including BIN and bPTP, further underscore taxonomic uniqueness of O. siangi sp. nov., within Chedrinae family. This description enriches our understanding of biodiversity within Siang River ecosystem and underscores the merit of employing multi-pronged approaches in taxonomic investigations.

Two new species of the congrid eel genus Ariosoma (Anguilliformes, Congridae, Bathymyrinae) from Indian waters

Two new species have been described from Indian waters, based on the materials collected from Kochi coast, Arabian Sea, Gulf of Mannar and West Bengal coast along the Bay of Bengal. Ariosoma gracilesp. nov. is described, based on five specimens collected from the landings at Kalamukku Fishing Harbour, Arabian Sea. The new species is characterised by longer tail, 55.3–58.7% TL; dorsal-fin origin above pectoral-fin base; no dark or whitish bands on dorsal surface of head, ventral extremities of lower jaw and mid-portion with minute dark pigmentation patch; anus positioned well before the middle of total length; SO canal with 4 pores; 0 or 3 pores on ST canal; pre-dorsal vertebrae 9; pre-anal vertebrae 49–54; total vertebrae 140–142. Ariosoma gracilesp. nov. is closely related to Ariosoma dolichopterum and Ariosoma emmae by sharing similar morphometrics and pre-anal vertebral counts. However, it differs by having more total pores (132–135 vs. 121–129 in A. dolichopterum, 123–126 in A. emmae); fewer pre-anal pores (43–46 vs. 47–51 in A. dolichopterum, 50–53 in A. emmae); more pre-dorsal pores (9 vs. 5–9 in A. dolichopterum, 4–6 in A. emmae). Another new species, Ariosoma kannanisp. nov. is described on the basis of two specimens (157–171 mm TL) from Gulf of Mannar and one specimen (201 mm TL) collected from Shankarpur Fish Landing Centre, West Bengal. This species is similar to Ariosoma megalops, but readily differs by having smaller eyes, smaller interorbital distance and exhibits 10.8% genetic divergence from A. megalops from the Taiwan waters.

Description of a new species of Phoxinus from the Ergene River (Aegean Sea Basin) in Türkiye (Actinopterygii, Leuciscidae)

Phoxinus radeki, a new species, is described from the Ergene River (Aegean Sea Basin). It is distinguished from Phoxinus species in Türkiye and the adjacent area by having the scales of the breast, scaled but separated unscaled area anteriorly, short dark rectangular blotches along the lateral line between the lateral line and belly yellowish in both males and females, body depth dorsal fin origin 16–21% SL, caudal peduncle depth 8–10% SL. Additionally, molecular results demonstrated that the new species differed from its closest congeners with a mean genetic distance value of 3.08% (min. 2.82–max. 3.29) and moderately support values in cytochrome b (Cyt b) gene partial sequences (1064 bp.). Further, the species delimitation analysis identified the new species as a single MOTU independent of other Phoxinus species.

Population variation of Diapoma pampeana (Characiformes, Characidae, Stevardiinae) from an isolated coastal drainage in Uruguay, with new records: comparing morphological and molecular data

Diapoma pampeana was recently described to occur in the upper Negro basin in Uruguay and Brazil. An isolated population tentatively identified as D. pampeana from the Pando stream, a perturbed coastal drainage in Uruguay, is studied and compared under the light of morphological and molecular data to test if there is evidence to consider it as a separate species. New geographical records for the species are presented and included in the comparisons. The specimens analyzed were pooled into four groups: Pando, Santa Lucía, Middle Negro and Upper Negro. We analyzed 32 morphological characters using statistical procedures and recovered a COI-based phylogeny of different populations of D. pampeana to test if they may represent different species. Size-corrected PCA revealed that the Pando and Upper Negro groups are greatly diverging in both morphometric and meristic data along PC1 (mainly by the snout to dorsal-fin origin, dorsal to adipose-fin origins, number of longitudinal scales and predorsal scales). This deviating pattern was also obtained in a cluster analysis. The Santa Lucía and Middle Negro groups were found to be intermediate morphotypes. In contrast, molecular analyses revealed that the Pando and Upper Negro specimens resemble genetically and, thus, are placed together in the Neighbor-joining and Bayesian topologies, as part of a monophyletic Diapoma. We proposed that the Pando population, despite its deviating morphology observed, can be classified as D. pampeana. Therefore, this population constitutes a remarkable example of an isolated population that is morphologically divergent but genetically similar to the geographically most distant conspecific population.

New species of the eel genera Dysomma and Dysommina from Vietnam, South China Sea (Anguilliformes: Synaphobranchidae).

Two new cutthroat eel species are described from Vietnam. Dysomma intermedium sp. nov. has a relatively long trunk, being about half of head length and anal-fin origin more than twice pectoral-fin length behind the pectoral-fin tip; pectoral fin well developed; dorsal-fin origin over or slightly in front of base of pectoral fin; two intermaxillary teeth; four or five compound teeth on ethmovomer; single row of seven or eight teeth on lower jaw; total lateral-line pores 70-76; and 21 pre-anal and 118-124 total vertebrae. Dysommina brevis sp. nov. differs from congeners by having a trunk shorter than head length, its length 11.1%-11.8% TL; a short pre-anal length 24.6%-25.6% TL, eye diameter 11.8%-12.3% head length; three large and one or two small teeth on ethmovomer; and fewer teeth on the upper and lower jaws. In addition, a specimen representing the first record of Dysommina orientalis in Vietnamese water is documented.

Morphological and molecular evidences confirm a new species in Ophichthus (Anguilliformes: Ophichthidae) from the east coast of India

A new species of snake eel, Ophichthus suryai sp. nov., is discovered based on six specimens collected from three different estuarine ecosystems in Odisha, India. The new species can be distinguished from its closely allied congeners Ophichthus alleni, Ophichthus zophistius, and Ophichthus altipennis, and other members in this genus by having the dorsal fin origin (DFO) just above or slightly anterior to the gill opening, its unique vertebral count (7-8/45-47/142-142), and teeth patterns consisting of multiple rows on both maxilla and mandible. The distinctiveness of this new species is also supported at the molecular level by a strongly supported (bootstrap value >99%) monophyletic grouping of the mitochondrial DNA (mtDNA) Cytochrome Oxidase I (COI) gene sequences of the holotype and one paratype. The current study describes the morphometric and meristic characters and molecular phylogeny of Ophichthus suryai sp. nov.

Description of a new species of Cyphocharax from the rio Juma, rio Aripuanã basin, southern Amazon basin (Teleostei: Curimatidae)

Abstract A new species of Cyphocharax is described from the rio Juma, which flows across the meridional Amazon basin and is a tributary of the rio Aripuanã in the rio Madeira fluvial system. Features distinguishing the new species from congeners include a longitudinally elongated caudal peduncle blotchextending from the vertical line through the adipose-fin terminus to the base of median caudal-fin rays, the number of scale series along the lateral line and between the lateral line and dorsal-fin origin, morphometric variation, and the patterns of pigmentation along the body. The species was discovered in a lesser-explored region and appears to be an endemic of the rio Aripuanã in the southern Amazon basin.

New reddish species of Moenkhausia Eigenmann (Characiformes: Characidae) from the upper rio Xingu basin, Brazil

Abstract A new species of Moenkhausia from the rio Culuene, rio Xingu basin, in Mato Grosso State is described here through genetic and morphological data. This new species differs from all congeners by the following combination of characters: the presence of reddish color on the posterior portion of the body, as well as on the base of anal, adipose, and pelvic fins in live specimens; a conspicuous midlateral dark stripe, which extends from posterior margin of opercle to the middle of caudal-fin rays, becoming wider and more conspicuous from the vertical through the dorsal-fin origin; absence of humeral blotch; absence of blotches on caudal-fin lobes; by having the concentration of dark pigments on the anterior margin of the caudal-fin rays; and presence of 2–3 maxillary teeth. A brief discussion about its putative relationships with other congeners is presented.

A new snake eel species of the genus Ophichthus (Anguilliformes: Ophichthidae) from the southeast coast of India, Bay of Bengal, with the taxonomic account of Ophichthus chilkensis.

A new species of the ophichthid eel of the family Ophichthidae is described based on five specimens collected from the Mudasalodai fish landing center, off Cuddalore coast, southeast coast of India, Bay of Bengal. Ophichthus naevius sp. nov. is distinguished from its congeners by having a unique color pattern: dorsal body with numerous dense dark spots or patches, ventral body pale yellowish green, dorsal-fin origin just before pectoral-fin tip, vertebral formula: 12-14/52-53/134-138, and teeth on jaw uniserial and pointed. The study also reports the range extension and molecular evidence of Ophichthus chilkensis from South India. Molecular analyses were performed for both species, and their phylogenetic relationship suggests that the new species exhibits 10.2% genetic divergence with its congener Ophichthus sangjuensis, followed by Ophichthus brevicaudatus (10.4%), and Ophichthus sp. 1 (11.8%) also forms the closest clade in both Bayesian inference and maximum likelihood (ML) tree. Similarly, according to the topology of the ML tree, the species O. chilkensis forms a clade with Ophichthus sp. 5, Ophichthus remiger, Ophichthus frontalis, Ophichthus sp. 6, and Ophichthus rex, suggesting that it would be the genetically closest congener.

Malakichthys formosus, a new species of small seabass (Acropomatiformes: Malakichthyidae) from southwestern Taiwan.

A new species of Malakichthys is described based on six specimens collected from deepwaters off southwestern Taiwan, northwestern Pacific Ocean. The new species, M. formosus sp. nov., exhibits distinct morphological characters, primarily characterized by the absence of chin spines, distinguishing it from other congeners with the exception of M. levis and M. mochizuki. It differs from the two species by having more lateral-line scales, a shorter distance between the snout and dorsal-fin origin, a shallower head, fewer scale rows below the lateral line, and the structure of the first anal-fin pterygiophore. Eight species are now recognized in Malakichthys.