Dorsal-fin Origin Research Articles

Morphological characteristics and population structure of Marbled Eel (Anguilla marmorata) in Thua Thien Hue, Vietnam

ABSTRACT The Marbled Eel (Anguilla marmorata) has a widespread distribution with a complex migration life cycle There were 350 individuals of sizes from 120 to 1137 mm were analysed on characteristic morphology at 4 developing stages: juvenile, fingerling, pre-adulthood and adulthood. Morphological indicators: total length (TL), head length (HL), dorsal fin origin (PD), anal fin origin (PA), distance from dorsal to anal fin (AD), distance from pectoral fins to dorsal fin (PDH), body length (TR), eye diameter (E), tail length (T) and eye distance (IO), colour characteristics and 10 characters were standardized against the LT or LH ratios determine 95.664% of morphological differences between individuals in the study population based on principal component analysis and hierarchical cluster analysis tools. Phylogenetic tree with five morphological clusters with distance > 2.0 built a high genetic diversity. The difference of clusters is related to the morphology at different stages. Cluster 1 corresponds to the morphological characteristics at the fingerling stage (TL = 260–552.0 mm); cluster 3 is the pre-adult stage (TL = 324.6–533.9); cluster 4 is the juvenile stage (TL = 120.0–255.0); and clusters 2 and 5 for pre-adult and adult at reproductive migration (TL > 400).

A New Species of the Bengal Spined Anchovy Stolephorus from the Eastern Indian Ocean and Redescription of Stolephorus dubiosus Wongratana, 1983, with Comments on the Evolution of Prepelvic Scute Numbers within Stolephorus (Clupeiformes: Engraulidae).

The Bengal Spined Anchovy, Stolephorus taurus sp. nov. is described from 21 specimens from the northern Bay of Bengal. The new species closely resembles Stolephorus dubiosus Wongratana, 1983, which is redescribed. Both species have a predorsal scute, spine on the pelvic scute, long maxilla posteriorly slightly short of or just reaching the posterior margin of the opercle, 25 or more gill rakers on the lower limb of the first gill arch, and double black lines on the dorsum posterior to the dorsal fin. However, the new species differs from S. dubiosus in having a longer pelvic fin with the posterior tip of the depressed fin beyond vertical through the dorsal-fin origin (vs. usually not reaching to vertical through dorsal-fin origin), longer pectoral fin, second dorsal-and third dorsal-fin rays, second anal-and third anal-fin rays, and greater interorbital width. Stolephorus taurus sp. nov. is closely related to Stolephorus baganensis Delsman, 1931 and S. dubiosus, although at least 2% mean p-distance divergence in the mitochondrial cytochrome c oxidase subunit I (COI) gene separates each of the three species. A phylogenetic reconstruction of the evolution of the number of prepelvic scutes within Stolephorus indicated that having six scutes was the most likely ancestral condition in the genus, and was later reduced in the evolution of Stolephorus to five or four scutes. One such reduction occurred recently in the lineage of Stolephorus taurus sp. nov.

Phylogenetic relationships and description of two new species of Diapoma (Characidae: Stevardiinae) from the La Plata River basin

Abstract Herein we describe two new species of Diapoma, one from the Negro River, a tributary of the Uruguay River in Brazil and Uruguay, and one from the Iguaçu River, in Brazil and Argentina. The new species from the Negro River basin is distinguished from its congeners by the following combination of characters: a black narrow and conspicuous line restricted to the body horizontal septum, incomplete lateral line, tricuspid teeth in the inner series of the premaxilla, and a lower body depth at vertical through the dorsal-fin origin (29.3–32.8% SL in males and 27.7–33.3% SL in females). The new species from the Iguaçu River basin is distinguished from its congeners by the following combination of characters: a discontinuous lateral line, adipose fin hyaline, longer anal-fin base (26.5–32.4% SL), and a longitudinal black stripe along the median region of caudal-fin rays. Additionally, we updated the molecular phylogeny of the genus, including new sequences from these two new species and Diapoma thauma. An identification key for species of Diapoma is presented, modified from previous study.

A new record of a rare labrid, Suezichthys notatus (Actinopterygii: Labridae), from Taiwan, with comparison to related species from Taiwan

Three specimens of a rare labrid, Suezichthys notatus (Kamohara, 1958) were recently collected from local markets, which were captured from deep-water off northern and southwestern Taiwan, and represent a new record for Taiwan. Suezichthys notatus can be distinguished from its congeners by a combination of characters: scale rows above lateral line 2½; low scaly sheath present at base of dorsal and anal fins; dorsal-fin element IX, 11; anal-fin elements III, 10; lateral line scales 25‒26, each with simple, unbranched laterosensory canal tube; cheek scale rows behind and below eye 2 and 2‒3 respectively; a group of prominent dark blotches extending from the interorbital region dorsoposteriorly; body depth at dorsal-fin origin 3.7‒3.9 in standard length; short pelvic fin without filamentous extension, 2.2‒2.5 in head length. Suezichthys resembles the labrid genus Pseudolabrus, comparison of Taiwanese species of Suezichthys with those of Pseudolabrus are given.

Garra hormuzensis, a new species from the upper Kol River drainage in the Persian Gulf basin (Teleostei: Cyprinidae).

Garra hormuzensis, new species, is described from the Kol River drainage. It is distinguished from its congeners in the Iranian part of the Persian Gulf basin by having 7 branched dorsal-fin rays, usually 9+8 branched caudal-fin rays, the breast, belly and back in front of the dorsal-fin origin covered by scales, and a free lateral and posterior margins of the gular disc. It is further characterised by having a minimum K2P distance of 1.16% to G. mondica in the mtDNA COI barcode region.

Stolephorus grandis, a new anchovy (Teleostei: Clupeiformes: Engraulidae) from New Guinea and Australia.

The new anchovy Stolephorus grandis n. sp., described on the basis of 10 specimens collected from Papua, Indonesia, and Australia, closely resembles Stolephorus mercurius Hata, Lavou Motomura, 2021, Stolephorus multibranchus Wongratana, 1987, and Stolephorus rex Jordan Seale, 1926, all having double pigmented lines on the dorsum from the occiput to the dorsal-fin origin, a long maxilla (posterior tip just reaching or slightly beyond the posterior margin of preopercle), and lacking a predorsal scute. However, the new species clearly differs from the others in having fewer gill rakers (3539 total gill rakers on the first gill arch in S. grandis vs. > 38 in the other species), a greater number of vertebrae (total vertebrae 4243 vs. fewer than 41), longer caudal peduncle (21.923.7% SL vs. 20.8%), and the depressed pelvic fin not reaching posteriorly to vertical through the dorsal fin-origin (vs. reaching beyond level of dorsal-fin origin).

Guiclupea superstes, gen. et sp. nov., the youngest ellimmichthyiform (clupeomorph) fish to date from the Oligocene of South China.

A new ellimmichthyiform, Guiclupea superstes, gen. et sp. nov., from the Oligocene Ningming Formation of Ningming Basin, Guangxi Zhuang Autonomous Region, South China is described herein. With relatively large body size, parietals meeting at the midline, anterior ceratohyal with a beryciform foramen in the center, a complete predorsal scutes series of very high number and about equally-size scutes with radiating ridges on dorsal surface, first preural centrum unfused with first uroneural but fused with the parhypural, and first ural centrum of roughly the same size as the preural centrum, Guiclupea superstes cannot be assigned to the order Clupeiformes. The phylogenetic analyses using parsimony and Bayesian inference methods with Chanos/Elops as outgroup respectively suggests that the new form is closer to ellimmichthyiform genus Diplomystus than to any other fishes, although there are some discrepancies between the two criteria and different outgroups used. It shares with Diplomystus the high supraoccipital crest, pelvic-fin insertion in advance of dorsal fin origin, and the number of predorsal scutes more than 20. The new form represents the youngest ellimmichthyiform fish record in the world. Its discovery indicates that the members of the Ellimmichthyiformes had a wider distribution range and a longer evolutional history than previously known.

Description of a new eelpout Pachycara angeloi sp. nov. (Perciformes: Zoarcidae) from deep-sea hydrothermal vent fields in the Indian Ocean.

A new species of eelpout genus Pachycara Zugmayer, 1911 is described based on five specimens caught at a depth of 24193275 m along the Central and Southeast Indian Ridges in the Indian Ocean. The specimens were collected during the INDEX cruises in 2016, 2018 and 2019, respectively. The new species is distinguished from its congeners by the following combination of characters: scales and pelvic fins absent; lateral line configuration mediolateral; dorsal fin origin associated with vertebrae 79 with no free predorsal pterygiophores; vertebrae 2728 + 5759 = 8587; dorsal-fin rays 7880, anal-fin rays 5862; pectoral fin rays 1315. DNA sequences of a mitochondrial COI gene fragment showed low intra-specific variation ranging from 00.3 % sequence divergence and do not reflect different vent sites. This is the 29th species of Pachycara, which is the fifth to be described from specimens collected only from chemosynthetic environments and the sixth known from the Indian Ocean.

Sardinella ventura n. sp. (Actinopterygii: Clupeiformes: Clupeidae), a new sardine from Mauritius.

The new sardine Sardinella ventura n. sp. (Teleostei: Clupeiformes: Clupeidae) is described on the basis of 10 specimens collected from Mauritius. The new species is most similar to Sardinella dayi Regan 1917 in having non-deciduous scales with pores and discontinuous striae, a dark spot on the dorsal-fin origin, the pelvic fin with 8 rays, and similar number of gill rakers, in addition to very similar numbers of keeled scutes. However, the new species is distinguished from S. dayi by having a shorter caudal peduncle [6.27.6% SL (mean 7.0%) vs. 8.212.0% (9.2%) in S. dayi], larger eye [8.49.9% (9.0%) vs. 6.88.0% (7.4%)] and orbit [9.612.3% (10.7%) vs. 8.510.2% (9.3%)], longer pectoral [21.022.7% (21.5%) vs. 17.021.0% (19.8%)] and pelvic fins [12.513.5% (12.8%) vs. 10.412.2% (11.2%)], and a greater numbers of pseudobranchial filaments [1719 (modally 17) vs. 1822 (19)], lateral scale rows in longitudinal series [4143 (41) vs. 3842 (40)] and transverse scales [11 or 12 (12) vs. 11]. There were significant differences in seven meristic and 14 morphometric characters between the two species.

Triplophysa ferganaensis, a new loach species from Fergana Valley in Central Asia (Teleostei: Nemacheilidae).

Triplophysa ferganaensis sp. nov. is described from the Shakhimardan stream, a small tributary of the Syr Darya, which does not reach the river in Fergana Valley. It can be distinguished from other valid Triplophysa loaches based on the following combination of characters: body smooth and scaleless, lateral line complete, posterior chamber of air bladder degenerated, inner gill rakers 10-11 on the first-gill arch, outer gill rakers absent, vertebrae 4 + 35-36, 8 + 8 branched caudal-fin rays, caudal peduncle depth 2.1-2.7 times its length, two supratemporal pores, dorsal-fin origin closer to the caudal-fin base than to the snout tip, caudal fin emarginated and pelvic-fin tip reaching the anus. The new species can also be distinguished from its congeners based on the molecular analyses of mitochondrial cytochrome oxidase subunit I (coI) gene sequences. The phylogenetic position of this new species indicates that it is a sister taxon of Triplophysa tenuis.

A new arrowtooth eel of genus emMeadia/em (Synaphobranchidae: Ilyophinae) from Vietnam, South China Sea.

Meadia minor sp. nov., a scaless ilyophine eel, is described on the basis of 10 specimens collected from off Quy Nhon, central coast of Vietnam. It can be distinguished from its congeners in having a relatively long trunk (21.3-25.0% TL) which is longer than head length; a short and blunt snout (21.4-23.7% HL); gill opening close to pectoral-fin base; interbranchial space broad (20.7-26.2% HL); dorsal-fin origin above posterior third of pectoral fin; body depth 24-28 times in TL; total vertebrae 118-122; mean vertebral formula 7-33-121; and a small body size, reaching 330 mm TL. The generic status of the new species is discussed. Short descriptions of two congeners are provided.

Chondrostoma smyrnae, a new nase from the Tahtalı reservoir drainage in the Aegean Sea basin (Teleostei, Leuciscidae)

Chondrostoma smyrnae, a new species, from the Tahtalı reservoir drainage is distinguished by having a slightly arched lower jaw with a well-developed keratinised edge, a deep and cylindric body, a complete lateral line with 47–52+1 total scales, 8–9 scale rows between the lateral line and the dorsal-fin origin, 4 scale rows between the lateral line and the pelvic fin-origin, and 19–23 gill rakers on the first gill arch. Moreover, molecular analyses using full cyt b (1141 bp) and partial coI (652 bp) sequences of the mitochondrial genome from specimens of the new species, C. smyrnae and specimens belonging to other Chondrostoma species from central and western Anatolia demonstrated that the C. smyrnae is easily differentiated by their high pairwise genetic distances of cyt b and coI data set (>2.20 and 1.03%, respectively) and by their position in the phylogenetic trees obtained through Maximum Likelihood (ML) methodology.

Oxynoemacheilus amanos, a new nemacheilid loach from the Orontes River drainage (Teleostei: Nemacheilidae).

Oxynoemacheilus amanos, new species, is described from İncesu spring in the upper Hupnik drainage, a northern tributary of the lower Orontes in Turkey. It is distinguished from the other Oxynoemacheilus species in the Eastern Mediterranean Sea basin by possession of an incomplete lateral line with 23-45 pores, terminating between the vertical through the dorsal fin origin and the anus, 10-13 pores in the infraorbital canal, a deeply emarginate caudal fin, no suborbital groove in the male, and a series of irregularly shaped and set dark-brown bars on the flank, not connected to saddles on the back.

Capoeta baliki Turan, Kottelat, Ekmekçi & Imamoglu, 2006 a junior synonym of Capoeta tinca (Heckel, 1843) (Teleostei: Cyprinidae)

Capoeta baliki was described from Sakarya basin, Turkey. It was distinguished from its nearest congener i.e. C. tinca based on a combination of characters, including fewer serrae along posterior margin of last simple dorsal-fin ray, modally fewer scale rows between lateral line and dorsal-fin origin, fewer vertebrae, deeper and shorter head and slenderer caudal peduncle. We examined the synonymy hypothesis of C.­ baliki and C. tinca by comparing their morphometric, meristic and molecular characters. Based on the results, their morphometric and meristic characters largely overlapped and no character was found to distinguish them. In addition, a low K2P mean genetic divergence of 0.37% C. baliki and C. tinca based on cyt b gene and clustering in same clad showed that they are identical in molecular characters. As no character could be found to clearly distinguish these species, we treat C. baliki as a junior synonym of C. tinca .

Description of two new species of sandlances, genus Bleekeria (Perciformes, Ammodytidae) from the Andaman Sea (northeastern Indian Ocean)

Two new species of Bleekeria Günther, 1862 are described from specimens collected in the Andaman Sea off the coast of Myanmar during bottom surveys conducted by the R/V Dr Fridtjof Nansen in 2015 and 2018. They are distinguished from each other and from congeners by a combination of morphological and meristic characters as well as fin coloration and genetic variance. Bleekeria albicauda sp. nov. has pelvic fins, 40–41 dorsal-fin rays, 54–55 total vertebrae, no teeth in jaws, 4 scale rows between dorsal-fin origin and lateral line, a single row of about 10 scales on mid-upper part of opercle, scales on central part of body clearly shorter than their height, caudal fin with white upper and lower lobes when fresh (unique within the genus). Bleekeria nigrilinea sp. nov. has no pelvic fins, 37–39 dorsal-fin rays, 49–50 total vertebrae, 2½ scale rows between dorsal-fin origin and lateral line (the smallest count within the genus with B. estuaria of Mozambique brackish water), 5–6 scales on mid-upper part of opercle arranged in a single row, scales on central part of body clearly longer than their height, upper and lower margins of caudal fin black when fresh (unique within the genus). The COI gene sequences of the two new species showed clear genetic divergence (pairwise K2P, >10 %) from Bleekeria estuaria Randall & Ida, 2014 and Bleekeria mitsukurii (Jordan & Evermann, 1902). A key to the species of Bleekeria is provided.

Two new species of Knodus (Characidae: Stevardiinae) from the upper rio Tocantins basin, with evidence of ontogenetic meristic changes

ABSTRACT Two new species from the upper rio Tocantins basin are described in Knodus based on the traditional definition of the genus. The new species are distinguished from other congeners by meristic and morphometric characters, such as the number of cusps in the premaxillary and dentary teeth, the number of scale series between dorsal-fin origin and lateral line, the orbital diameter and the body depth. With the two new species, the number of endemic species in the upper rio Tocantins basin upstream of the mouth of the rio Paranã, rises to 53 (89 to the confluence with rio Araguaia). The existence of a meristic character that changes through ontogeny (allomery), viz. the number of scale series between dorsal-fin origin and lateral line, was detected in some species of Knodus through a regression analysis. Additionally, this paper describes an unambiguous, more informative and precise new method for counting vertebrae, which will enhance the efficacy of this trait in species comparisons.

A new, narrowly distributed, and critically endangered species of Characidium (Characiformes: Crenuchidae) from the Distrito Federal, Central Brazil

ABSTRACT A new species of Characidium is described from the Cerrado biome, in Brasília, Distrito Federal, Central Brazil. The new species can be readily diagnosed by the presence of two or three longitudinal rows of dots along the body sides, absence of bars, by the short pectoral fin, which does not reach the vertical through the dorsal fin origin. Additional useful diagnostic characters are the scaled isthmus, absence of the adipose fin, and the terminal mouth. The new species is only known from the córrego Taquara and its tributaries, a tributary of ribeirão do Gama, upstream from lago Paranoá, in the upper rio Paraná basin. In accordance to the IUCN Red List Categories and Criteria, the new species is categorized as Critically Endangered.

A new species Ophichthus chennaiensis sp. nov. (Anguilliformes: Ophichthidae) from the southeast coast of India.

A new species of snake eel, Ophichthus chennaiensis sp. nov. (Anguilliformes: Ophichthidae: Ophichthinae), is described on the basis of a specimen collected from dumped fish disposed ofby bottom trawlers at Kasimedu fishing harbour, Chennai. Ophichthus chennaiensis sp. nov is distinguished from its congeners by having its dorsal-fin origin one pectoral-fin length behind the pectoral-fin tip, preanal length 2.4 in TL, biserial maxillary, uniserial mandibular teeth, biserial to uniserial vomerine teeth, and its vertebrae (predorsal 19, preanal 53, and total vertebrae 154).

Two new species of loaches from the Irrawaddy River basin, Chin State, Myanmar (Teleostei: Cypriniformes: Nemacheilidae).

Schistura falamensis, a new species of nemacheilid loach, is described from the main channel of the Manipur River in the Irrawaddy River basin, Chin State, western Myanmar. It differs from other congeners of the genus Schistura by a combination of the following characters: 5-8 vertical bars on body; indistinct bars in front of dorsal-fin origin; bars on posterior part of body regular, twice as wide as interspace; black caudal basal bar dissociated, short, not reaching ventral extremity; males with suborbital flap; lateral line complete; and processus dentiformis weak. Schistura altuscauda is a new species described from the Htin stream, Mindat Town, Chin State, Myanmar. It can be distinguished from other congeners by a combination of the following characters: high caudal peduncle (14.0-20.3% SL), strong processus dentiformis on upper jaw; 7-19 bars on flank of body, bars in front of dorsal fin obviously thinner than those behind, sometimes fused in front of dorsal fin; lateral line complete; males with prominent suborbital flap; and pelvic lobe present.

Stigmatopora harastii, a new species of pipefish in facultative associations with finger sponges and red algae from New South Wales, Australia (Teleostei, Syngnathidae).

A new species of pipefish, Stigmatopora harastiisp. nov., is described based on the male holotype and two female paratypes, 136.3–145.5 mm SL, collected from red algae (sp.?) at 12 meters depth in Botany Bay, New South Wales (NSW), Australia. The new taxon shares morphological synapomorphies with the previously described members of Stigmatopora, including principle body ridges, fin placement, slender tail, and absence of a caudal fin. It is morphologically and meristically similar to Stigmatopora nigra, including snout length and shape, dorsal-fin origin on 6th–7th trunk ring, and lateral trunk ridge terminating on the first tail ring. Stigmatopora harastiisp. nov. is distinguished from its congeners, however, by characters of the head and first trunk ring, distinct sexual dimorphic markings on sides and venter of anterior trunk rings, and red background coloration in life. The new taxon can be further differentiated by genetic divergence in the mitochondrial COI gene (uncorrected p-distances of 9.8%, 10.1%, 10.7%, and 14.6%, from S. argus, S. macropterygia, S. narinosa, and S. nigra, respectively). The type locality is characterised by semi-exposed deep-water sandy areas interspersed with boulders, flat reefs, and an absence of seagrass beds, in which S. harastii has been observed living in facultative associations with a finger sponge and red algae at depths of 10–25 meters, compared to the shallow coastal and estuarine habitats preferred by the fucoid algae and seagrass-associating members of Stigmatopora. Stigmatopora harastiisp. nov. represents the fourth species of Stigmatopora recorded in temperate southern Australia.