Suborbital Flap Research Articles

Physoschistura longibulla, a new loach (Cypriniformes: Nemacheilidae) from Irrawaddy basin in central Myanmar

Physoschistura longibulla, a new species and the first species of the revised genus Physoschistura from Pyin Oo Lwin of Irrawaddy basin, can be distinguished from other congeners by the combination of following characters: posterior chamber of air bladder well developed, connecting anterior with a long and thin tube, long and oval; dorsal fin with 81/2 branched rays, its origin slightly anterior to pelvic-fin base vertically; lateral line complete and straight, with 93–102 pores; pectoral fin with 8–9 branched rays, reaching 1/2 to 2/3 of distance to pelvic-fin base; suborbital flap absent in male; axillary pelvic lobe present; caudal fin with 9 + 8 branched rays.

Mustura daral, a new species of stone loach from Arunachal Pradesh, Northeast India (Teleostei: Nemacheilidae).

Mustura daral, new species, is described from the Siang River (Brahmaputra drainage) in Arunachal Pradesh, Northeast India. The new species is distinguished from its congeners by: 910 dark-brown saddles on dorsum, each continued down on flank forming regularly set and shaped dark-brown bars; two black blotches at caudal-fin base; caudal fin forked with 9+8 branched rays; lateral line complete; median notch in lower jaw absent; axillary pelvic lobe large; and suborbital flap in male with conspicuous tubercles along posterior rim.

Nemacheilus pezidion, a new species of loach from southern Laos (Teleostei: Nemacheilidae).

Nemacheilus pezidion, new species, is described from the Xe Kong watershed, Mekong drainage, in Attapeu province, southern Laos. It is distinguished from all other Nemacheilidae in Southeast Asia by its unique colour pattern consisting of a black midlateral stripe and a middorsal row of 1115 narrow saddles. Besides, the male has a globulous suborbital flap with tubercles along its posterior edge, and the pectoral fin with thickened anterior rays, and branched rays 14 and unculiferous pads behind them covered by small tubercles. It was found in habitats with moderate flow, on mud to gravel bottom. Nemacheilus pezidion was earlier misidentified as N. longistriatus.

A practical approach to revise the Oxynoemacheilus bergianus species group (Teleostei: Nemacheilidae).

The Oxynoemacheilus bergianus species group is revised based on tree topology (ML, NJ, MP), distance (K2P and ASAP) and Poisson tree process analyses of DNA barcode data tested against morphometric and morphological characters including colour patterns. The O. bergianus species group is distinguished from other Oxynoemacheilus groups based on morphological characters: its constituent species have a slender caudal peduncle, a suborbital flap in the male, a mottled or blotched colour pattern, and lack bold, black spots on the caudal-fin base. It is also supported as a monophyletic unit in our molecular analysis. The O. bergianus group includes 10 molecular clades following congruently well-supported NJ, MP and ML based entities. Species described as O. bergianus, O. banarescui, O. erdali, O. fatsaensis, O. samanticus, and O. simavicus from Turkey, O. lenkoranensis from Azerbaijan, and O. longipinnis and O. parvinae from Iran belong to this species group. The group includes also four unnamed molecular clades. We were unable to detect external differences between any of the molecular clades in colour pattern or any morphometric or morphological characters examined. In the 10 molecular clades in the O. bergianus species group, the intraclade K2P distance ranges from 0.01.8% while the distances between molecular clades ranges from 0.65.9%. To resolve the species diversity of this group, we also analysed the intraspecific and interspecific variability in the K2P distance of DNA barcode data from 53 other Oxynoemacheilus species. Here, the intraspecific variability ranges from 0.02.4% while the interspecific K2P distance ranges from 1.220.8%. In the O. bergianus species group, only four groups are detected by the mPTP species delimitation approach distinguished by a K2P distance of 2.9% or more. We treat these four groups as valid species, corresponding to O. banarescui, O. bergianus, O. fatsaensis, and O. simavicus. Oxynoemacheilus samanticus from the Kzlrmak and Seyhan drainages, O. lenkoranensis from the Caspian basin, O. erdali from the Euphrates, and O. longipinnis and O. parvinae from the Tigris drainage are treated as synonyms of O. bergianus. Fishes from an unnamed molecular clade from the upper Tigris, and from a second unnamed clade from the upper Euphrates, are both identified as O. bergianus. Oxynoemacheilus bergianus might be a junior synonym of O. bergi from the Kura. The distribution range of O. simavicus, described from the Simav drainage in the Marmara basin, is expanded to the east and two molecularly differentiated population groups occur in the Sakarya drainage, the Byk Melen River and potentially in other adjacent coastal streams. Oxynoemacheilus fatsaensis, described from the coastal stream Eleki in northern Anatolia, is also widespread in the Yeilrmak drainage. Morphological characters proposed to distinguish O. fatsaensis from the other species of the O. bergianus group could not be confirmed by our data on fishes from the Yeilrmak. This study also discusses the theoretical background, our reasons for conducting this revision in the way we did, and what the alternatives would be.

A new species of stone loach of the genus Mustura (Teleostei: Nemacheilidae) from Chindwin River drainage, Manipur, north-eastern India.

Mustura taretensis, a new nemacheilid loach, is described from the Taret River, a tributary of the Yu River, Chindwin River drainage, Manipur, India. The new species is distinguished from all its congeners by a unique combination of the following characters: body with 1213 irregular dark-brown blotches or bars on flank, alternating with 1116 irregular dark-brown saddles on the back; dorsum of head with a distinctly visible rhomboid dark-brown mark encircling a pale oval area on the nape; dorsal fin with 9 or 10 branched rays; lateral line complete; a well-developed free posterior chamber of air bladder, the halves of air bladder capsules connected by a manubrium; poorly developed processus dentiformis; suborbital flap present in males; and body depth 12.816.0 % SL. The generic status of Mustura chindwinensis, M. dikrongensis, M. tigrina and M. tuivaiensis are also discussed in the paper.

'Nemacheilus' argyrogaster, a new species of loach from southern Laos(Teleostei: Nemacheilidae).

'Nemacheilus' argyrogaster, new species, is described from the Xe Kong, Mekong drainage, in Attapeu and Xe Kong provinces, southern Laos. It is distinguished from all other Nemacheilidae in Southeast Asia by its unique colour pattern made of a bold black midlateral stripe separating the yellowish brown dorsal part of the body from the silvery whitish ventral part and a middorsal row of 14-19 thin saddles. Besides, the male has a globulous suborbital flap with tubercles along its free, posterior edge, and the pectoral fin with thickened anterior ray and branched rays 1-4 and unculiferous pads behind them covered by small tubercles; lips thin, lower lip continuous with a narrow median notch. It was found in moderate to fast flowing water, over pebble to stone bottom. 'Nemacheilus' argyrogaster, was earlier misidentified as N. longistriatus; it is provisionally placed in the genus Nemacheilus.

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.

Paraschistura makranensis, a new loach from the Jegin River drainage in southern Iran with comments on P. ilamensis and P. pasatigris (Teleostei: Nemacheilidae).

Paraschistura makranensis, new species, is described from the Jegin River drainage in southern Iran. It is distinguished from its congeners in Iran by having a plain brown or slightly mottled colour pattern on the flanks, a very slender body with a relatively short head, a complete lateral line extending almost to the caudal-fin base, the caudal peduncle covered by scales, and a suborbital flap in males. Paraschistura makranensis is distinguished from P. bampurensis and P. hormuzensis, its closest relatives in our dataset, by an uncorrected-pairwise distance based on the COI data of 4.0 and 5.4%, respectively. We treat Paraschistura pasatigris as a synonym of P. ilamensis.

Rhyacoschistura larreci, a new genus and species of loach from Laos and redescription of R. suber (Teleostei: Nemacheilidae).

Rhyacoschistura, new genus, belongs to a group of genera (Physoschistura, Mustura, Pteronemacheilus, Petruichthys) characterised by the modified branched pectoral-fin rays of males, with a very thick first ray, usually without membranes between some of the branches and/or rays, and anterior rays and/or membranes covered by small tubercles at maturity. Rhyacoschistura is distinguished from them by the combination of: presence of a suborbital flap; emarginate caudal fin; lower lip with a wide median interruption and connected to isthmus by a frenum; body depth about equal from behind head to caudal-fin base. Rhyacoschistura larreci, new species, is described from the Mekong drainage in Xayaburi Province, Laos. It is distinguished by details of the morphology of the pelvic fin, and its colour pattern (flank with numerous narrow slanted bars, very irregularly organised and shaped, more or less connected, or sometimes covering the whole flank). Schistura suber, from Nam Ngum watershed, is redescribed on the basis of adults and placed in Rhyacoschistura.

A new species of stone loach (Teleostei: Nemacheilidae: Schistura)from Arunachal Pradesh, India.

Schistura rebuw, new species, is described from the Kameng River, a north-bank tributary of the Brahmaputra, Arunachal Pradesh, India. The new species is easily distinguished from all known congeners in the Brahmaputra basin by its unique sexual dimorphism, specifically a suborbital slit in adult females, and a suborbital flap in adult males; and a colour pattern of 10-11 blackish bars on a greyish-beige body, the pre-dorsal bars mostly broken or incomplete, coalescing dorsally in a more or less alternate fashion.

A new species of Schistura (Teleostei: Nemacheilidae) from the south-western lowlands of Sri Lanka.

Schistura scripta, new species, is described from Nakiyadeniya in the south-western lowlands of Sri Lanka. It can be distinguished from all other congeners from Sri Lankan and peninsular India by the combination of the following characters: an incomplete lateral line with 53-76 pores, ending beneath the dorsal-fin base or slightly beyond; 7-13 post-dorsal bars; 7½ branched dorsal-fin rays; absence of an axillary pelvic lobe; and absence of a suborbital flap.

Physoschistura chhimtuipuiensis, a new species of loach (Teleostei: Nemacheilidae) from Mizoram, north-eastern India.

Physoschistura chhimtuipuiensis, new species, from a tributary of the Kaladan River in Mizoram, northeastern India, is distinguished from all other species of Physoschistura by a combination of the following characters: scales between pectoral- and pelvic-fin bases deeply embedded and sparsely set, lateral line incomplete with 56-63 pores, reaching slightly beyond the base of the last anal-fin ray, a suborbital flap in male, 8½ branched dorsal-fin rays and 8+7 branched caudal-fin rays.

Schistura phamhringi, a new stone loach from Chindwin Basin in Manipur,India (Cypriniformes: Nemacheilidae).

Schistura phamhringi, new stone loach, is described from Dutah Stream, tributary of the Yu River (Chindwin basin), near Larong Village, Chandel District, Manipur, India. It is distinguished from all its congeners by a unique combination of characters: 6-7 black saddles, each continued on both flanks forming broad diamond-shaped black bars with narrow ventral margin; bars superimposed on a grey stripe along lateral line; upper lip with numerous melanophores; black basicaudal bar arc-shaped; complete lateral line; and prominent oar-like suborbital flap on male.

A new species of Physoschistura (Pisces: Nemacheilidae) from northern Thailand.

Physoschistura chulabhornae, new species, is described from Maechaem River, a tributary of Ping River, upper Chaophraya River drainage, Chiangmai province, Thailand. It is distinguished from all other known species of Physoschistura in having an incomplete lateral line reaching at least to the origin of the anal fin with 62-83 lateral-line canal pores, the dorsal-fin origin slightly in front of the pelvic-fin origin, no axillary pelvic lobe, and a suborbital flap in the shape of a hammer head in the male.

Two new species of stone loaches of the genus Schistura from the Koladyne basin, Mizoram, India (Teleostei: Cobitoidei: Nemacheilidae)

Two new species of Schistura are described from the Koladyne basin of Mizoram, India. Schistura nebeshwari is distinguished from its congeners by the combination of the following characters: a prominent dorsal adipose crest on the caudal peduncle, 11-14 dark olivaceous bars on the body, the entire ventral surface of head with numerous small melanophores, an incomplete lateral line, three black spots at the dorsal-fin base, a complete prominent black basicaudal bar, lower jaw with a shallow median notch, and no suborbital flaps in males. Schistura scyphovecteta differs from its congeners by the combination of the following characters: six dark brown saddles, each one continuing to the flank, forming globular-shaped bars overlaying a background brown stripe along the lateral line, a complete lateral line, two black spots at the dorsal-fin base, an incomplete black basicaudal bar, no median notch on the lower jaw, and a suborbital flap present in males.

Schistura porocephala, a new nemacheilid loach from Koladyne basin, Mizoram, India (Teleostei: Nemacheilidae)

Schistura porocephala, a new nemacheilid species, is described from a stream that drains into the Mat River (Koladyne basin), India. It is characterized by the presence of prominent pores in the cephalic lateral line system; an incomplete lateral line; 20–23 thin dark olivaceous bars on the body, often bifurcated from the dorsolateral region; a depressed head and body anterior to the dorsal fin origin; and an elongated suborbital flap arising in front of the nostril and extending to the anterior one-third of the eye diameter in males.

Redescription of Schistura myrmekia (Fowler 1935) (Teleostei: Nemacheilidae)

Schistura myrmekia (Fowler 1935) was originally described from a single specimen collected from Keng Sok,southwestern Thailand. It was differentiated from a similar species, S. desmotes (Fowler 1934), by having four—ratherthan three—dark bands behind the dorsal fin, and the presence of a wart-like suborbital flap. Although S. myrmekia hassince been placed in the synonymy of S. desmotes, it is distinguishable by the size and orientation of the suborbital flap,a much shorter maxillary barbel, and a more slender appearance. The holotype, the only known specimen of S. myrmekia,is redescribed and contrasted with other species of Schistura in southern Thailand. Schistura myrmekia is known onlyfrom the holotype, collected in an area that recently has been highly modified by human activities. Recent efforts to find the species have failed, and it is probably extinct.

Physoschistura dikrongensis, a new loach from Arunachal Pradesh, India (Teleostei: Nemacheilidae)

A new species of nemacheilid, Physoschistura dikrongensis, is described from the Brahmaputra basin in ArunachalPradesh, India. It is easily distinguishable from congeners in having two V-shaped dark brown bars across the caudal fintowards the distal end; 11–15 irregular bars on the body; dark brown mottled markings on the head; 4 simple and 8½branched dorsal-fin rays; 4 simple anal-fin rays; an incomplete lateral line; a forked caudal fin with 8+7 branched rays; a well-developed axillary pelvic lobe; suborbital flap in males, and nine preoperculo-mandibular sensory canal pores.

Sexual dimorphism in species of Schistura (Teleostei: Nemacheilidae) from the Mae Khlong basin and peninsular Thailand

Sexually dimorphic characteristics are described for four species of Schistura from the Mae Khlong basin and peninsularThailand. Males of S. mahnerti have a suborbital flap and rows of unculi on the upper surfaces of the pectoral-fin rays.Females of S. mahnerti have a suborbital groove. None of the morphological measurements differ significantly betweenmales and females of S. mahnerti. In the other three species, S. aurantiaca, S. cf. aurantiaca, and S. sexcauda, all indi-viduals lack the flap or groove, but most males have a conspicuous black botch on the procurrent rays of the upper lobeof the caudal fin, a feature absent in most females. Some morphometric characteristics vary between sexes of these spe-cies. Sexually dimorphic traits presumably have a function related to reproduction; however, little is known about reproduction in Schistura, and variation in morphology in relation to habitat or other environmental factors has not been studied.

Schistura albirostris, a new nemacheiline loach (Teleostei: Balitoridae) from the Irrawaddy River drainage of Yunnan Province, China

Schistura albirostris, a new species of nemacheiline loach, is described from the Longchuanjiang, a tributary of theIrrawaddy River of Tengchong County, southwestern Yunnan, China. It differs from all congeners in the combination ofan extremely slender body; a distinctive rectangular unpigmented area on the snout, ethmoid region and anterior rostralbarbels; 5–7 dark dorsal saddles that are confluent with 5–8 lateral bars; lacking a suborbital flap in males; and possessing an incomplete lateral line with 27–51 pores, and a weakly-developed processus dentiformis.