A New Species of the Blind Cave Loach Genus Protocobitis (Cypriniformes: Cobitidae), Protocobitis longicostatus sp. nov., from Guangxi, China.

Protocobitis species are typical cave-dwelling fish, exhibiting distinctive morphological adaptations such as colorless body, lack of eyes, and reduced scales and ribs in response to their extreme cave habitats. Distinct from the recorded species, P. anteroventris, P. polylepis, and P. typhlops, a new species, Protocobitis longicostatus sp. nov., is described from Guangxi Zhuang Autonomous Region, China. Protocobitis longicostatus sp. nov. can easily be distinguished from all known congeners by the following characteristics: whole body covered by scales except head, 12 branched caudal fin rays, and long ribs. These species face threats from habitat degradation, hydrological changes, and environmental pollution. Thus, the conservation of cavefish in China has become an urgent issue.

A new cavefish of Sinocyclocheilus (Teleostei: Cypriniformes: Cyprinidae) from the Nanpanjiang River in Guizhou, China.

A new species, Sinocyclocheilus xingyiensis, is described based on specimens collected from a karst cave in Guizhou Province, China. The authors used an integrated taxonomic approach, including morphological and molecular data, to identify the new species as a member of the Sinocyclocheilu angularis group, and it can be distinguished from all other members of this group by a combination of the following features: two pairs of long barbels and long pectoral fins, 42-46 lateral-line scales, 7 (13-14) on outer (inner) side of the first gill arch and 35 (14-15 + 4 + 16 - 17) vertebrae. Phylogenetic analyses based on the cytochrome b (cyt b) gene fragment suggest that S. xingyiensis is a sister lineage to Sinocyclocheilus flexuosdorsalis. The genetic distance (Kimura 2-parameter) between the S. xingyiensis and S. angularis groups of Sinocyclocheilus species based on cyt b gene fragment ranged from 1.2% to 15.4%.

Descriptions of two new species of the botiid genus Leptobotia Bleeker, 1870 (Teleostei: Cypriniformes) from South China.

Two new species of Leptobotia are here described as L. rotundilobus from the Xin'an-Jiang of the upper Qiantang-Jiang basin in both Anhui and Zhejiang Provinces and the Cao'e-Jiang in Zhejiang Province, and L. paucipinna from the Qing-Jiang of the middle Chang-Jiang basin in Hubei Province, South China. Both have a plain brown body as found in L. bellacauda Bohlen & Slechtová, 2016, L. microphthalma Fu & Ye, 1983, L. posterodorsalis Chen & Lan, 1992 and L. tientainensis (Wu, 1930). The two new species are distinct from these species in vertebral counts, further from L. posterodorsalis in vent placement and further from the other three species in pectoral-fin length. Both differ in caudal-fin coloration and shape, and dorsal-fin location and coloration, and also in internal morphology. Their validity is confirmed by their own monophyly recovered in a phylogenetic analysis based on the mitochondrial cyt b and COI genes.

Review of the spotted lizard loaches, Pseudohomaloptera (Cypriniformes: Balitoridae) with a re-description of Pseudohomaloptera sexmaculata and description of a new species from Sumatra.

A review of the six recognized species of Pseudohomaloptera is provided. Counts in the original description of Pseudohomaloptera sexmaculata Fowler (1934) were incorrect and led to confusion in identifying populations of Pseudohomaloptera in mainland Southeast Asia, and the species is re-described. The validity of Homaloptera septemmaculata Fowler (1934) is investigated and confirmed as a junior synonym of P. sexmaculata. P. sexmaculata and Pseudohomaloptera leonardi, similar morphologically and often misidentified, are widely distributed in mainland Southeast Asia, with P. sexmaculata in the Chao Phraya, Mae Klong and Pran Buri River basins, and P. leonardi in the Malay Peninsula and the Chao Phraya and Mekong River basins. Pseudohomaloptera yunnanensis and Pseudohomaloptera vulgaris have been reported from the Mekong basin of Thailand and Laos but appear to be restricted to Yunnan Province, China. A new species of Pseudohomaloptera is described from Sumatra. This is the southern-most species and first record for the genus from the Indonesian island. An identification key is provided for all species of the genus.

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.

Morphology and reproductive biology of two hill stream Cyprinids, Balitora brucei and Psilorhynchus balitora, from the Ranganadi River (India), with a special note to their conservational threats.

The current work represents the study on morphology and reproductive biology of two indigenous torrential fishes, Balitora brucei and Psilorhynchus balitora, for the first time. The Gray's stone loach Balitora brucei and balitora minnow Psilorhynchus balitora abound in the torrential water bodies of South East Asia. The current paper redescribes morphology based on the fresh collection. Specific parameters of reproductive biology on both the fishes have been studied for the first time. Both the species were adapted to the same ecological conditions of the river Ranganadi. Fish specimens were collected at a fortnightly interval from the river in the Lakhimpur district of Assam, India. The detailed study includes morphological data analyzed with Mann-Whitney U-test and specific reproductive parameters such as condition factor (K), gonado-somatic index (GSI), modified gonado-somatic index (MGSI), and Dobriyal index (DI). Progressive development of the gonads was confirmed with dissection and histological study. Both the species are multiple breeders with prolonged reproductive seasons ranging from 4 to 5 months. Both the fishes are found to be migrants from upstream, and a good number of individuals were recorded during the monsoon season, reflecting the sampling site as a breeding ground. During winter, the local people use various chemicals, piscicidal plants, and electric instruments for fishing resulting in a steep decline in the number of individuals for both the species. Moreover, the effect of the North Eastern Electric Power Corporation Limited (NEEPCO) dam is evident on the decline of the ichthyofaunal diversity of the river. The results of present study will provide the baseline information on these two species of fishes for planning conservation measures in future.

Oxynoemacheilus isauricus, a new nemacheilid loach from Central Anatolia (Teleostei: Nemacheilidae).

Oxynoemacheilus isauricus, new species, from the Lakes Beysehir and Sugla basins in Central Anatolia is distinguished from all other species of the O. angorae group by having a very slender caudal peduncle (its depth 2.22.6 times in its length). The new species is further distinguished by having a short head (head length 2124% SL), and a midlateral series of irregularly shaped blotches on the flank. Oxynoemacheilus isauricus is also distinguished by a minimum K2P sequence divergence of 7.5% and 8.0% in the mtDNA-COI barcode region from O. eregliensis and O. atili, its closest relatives.

Oxynoemacheilus nasreddini, a new nemacheilid loach from Central Anatolia (Teleostei: Nemacheilidae).

Oxynoemacheilus nasreddini, new species, from Lake Aksehir, Eber, Egirdir, and Ilgin basins in Central Anatolia is distinguished from other species of Oxynoemacheilus in Central Anatolia by having irregularly shaped blotches on flank; 24 dark-brown bands on caudal fin; a slender body, and an emarginate caudal fin in which the shortest middle caudal-fin ray is 7691% of the longest ray of the upper caudal-fin lobe. Molecular data suggest that the new species is closely related to O. mediterraneus from the Aksu and Köprüçay drainages. Although the two species are separated by only a minimum K2P distance of 1.2% in the mtDNA COI barcode region, they are well distinguished morphologically. The situation is complicated by loaches from Lake Egirdir basin that are identified as O. nasreddini by their morphological character states but are only distinguished from O. mediterraneus by a minimum K2P distance of 0.2% in the mtDNA COI barcode region.

A new loach species of Troglonectes (Teleostei: Nemacheilidae) from Guangxi, China.

A new species of the genus Troglonectes is described from Guangxi Zhuang Autonomous Region, China. Troglonectes hechiensis sp. nov. can be easily distinguished from its congeners based on the following characters: eyes normal; whole body covered by scales except head, throat, and abdomen; lateral line incomplete; caudal fin concave; and color pattern present on body.

The fast and the tendinous? Locomotor modifications of the caudal peduncle in Gila spp. from the American Southwest.

In the American Southwest, the fishes within the genus Gila evolved in an environment with seasonal rainstorms that caused stochastic flooding. Some species within this genus, such as bonytail (Gila elegans), possess locomotor morphologies that are similar to those seen in high-performance swimmers such as tuna and lamnid sharks. These shared features include a shallow caudal peduncle, lunate tail, and mechanisms to transmit force from the anterior musculature to the tail fin. We compared the skeletal anatomy of the caudal region of bonytail to roundtail chub (Gila robusta) and humpback chub (Gila cypha) to determine which vertebral elements have been modified to create a shallow peduncle. We also tested the tensile strength of the red (slow oxidative) axial muscle by performing a standard stress test. If the muscle can withstand a large load, this suggests it may play a tendon-like role in transmitting force from the anterior muscle to the hypural plate of the tail. Lastly, we measured the collagen content of the red axial muscle (visualized using serial sections and Masson's trichrome stain) to determine if increased tensile strength is associated with increased collagen content. We found bonytail caudal peduncles are characterized by acute vertebral spines and have red axial muscle that can resist tearing under tension. Roundtail chub peduncles are characterized by relatively more obtuse angles and the red muscle tears easily under tension. Humpback chub possess an intermediate morphology, with relatively obtuse vertebral spine angles and the red muscle can resist tearing under tension. Bonytail have increased collagen content in posterior red axial muscle compared to the anterior musculature also suggesting a tendon-like role of the posterior red muscle. In combination with previous studies of swimming performance, our findings suggest that the axial musculature of bonytail may play a role in transmitting force directly to the shallow peduncle in a manner similar to that of the great lateral tendon of scombrids.

A review of the Cypriniform tribe Yunnanilini Prokofiev, 2010 from China, with an emphasis on five genera based on morphologies and complete mitochondrial genomes of some species.

The loach tribe Yunnanilini from China is reviewed here using morphological characters and complete mitochondrial genomes of select species. Molecular data suggest that the tribe Yunnanilini is not monophyletic and can be divided into three clades. Species of the Yunnanilus nigromaculatus group form an independent genus and are placed in Eonemachilus. In the phylogenetic tree, Y. jinxiensis clusters with Paranemachilus genilepis, and Y. pulcherrimus clusters with Micronemacheilus cruciatus, indicating that Y. jinxiensis and Y. pulcherrimus belong to Paranemachilus and Micronemacheilus, respectively. Based on morphological data, Y. bailianensis and Y. longibarbatus are placed in Heminoemacheilus, while Y. jinxiensis and Y. pulcherrimus, are placed in Paranemachilus and Micronemacheilus, respectively. Yunnanilus niulanensis and Y. qujinensis are treated as junior synonyms of Eonemachilus caohaiensis. Eonemachilus, Micronemacheilus, and Yunnanilus are show short separation between anterior and posterior nostrils. The genera can be distinguished from each other by mouth structure, lateral line and cephalic lateral-line canals, and papillae on median part of both lips. The anterior and posterior nostrils of Heminoemacheilus and Paranemachilus are closely set. Paranemachilus and Micronemacheilus are distinguished by cheeks covered with scales and lips with papillae, respectively. Our phylogenetic tree and morphological characters support Traccatichthys as a valid genus, which can be distinguished from Micronemacheilus by anterior and posterior nostrils closely set (vs. clearly separated). Four species are placed in Traccatichthys.

Yunnanilus chuanheensis, a new loach species (Cypriniformes: Nemacheilidae) from the upper Lixianjiang River in Yunnan, China.

A new loach species (Cypriniformes: Nemacheilidae: Yunnanilini), Yunnanilus chuanheensis sp. nov., was caught from Chuanhe in the upper reaches of the Lixianjiang River, a tributary of the Red River in Nanjian County, Yunnan Province, China. This species is a member of the traditional Y. pleurotaenia species group based on the presence of a lateral line and cephalic lateral-line canals. It can be distinguished from other species in the Y. pleurotaenia species group by the following characters: lips without papillae, anterior and posterior nostrils separated, whole body scaled, eye diameter smaller than interorbital width, outer gill raker absent on first gill arch, eye diameter greater than 18% of head length, 10-11 inner gill rakers on first gill arch, and lateral line not extending to vertical through dorsal fin insertion. To the best of our knowledge, this is the first Yunnanilus species recorded from the Red River drainage.

Skeletal and muscular pelvic morphology of hillstream loaches (Cypriniformes: Balitoridae).

The rheophilic hillstream loaches (Balitoridae) of South and Southeast Asia possess a range of pelvic girdle morphologies, which may be attributed to adaptations for locomotion against rapidly flowing water. Specifically, the connectivity of the pelvic plate (basipterygium) to the vertebral column via a sacral rib, and the relative size and shape of the sacral rib, fall within a spectrum of three discrete morphotypes: long, narrow rib that meets the basipterygium; thicker, slightly curved rib meeting the basipterygium; and robust crested rib interlocking with the basipterygium. Species in this third category with more robust sacral rib connections between the basipterygium and vertebral column are capable of walking out of water with a tetrapod-like lateral-sequence, diagonal-couplet gait. This behavior has not been observed in species lacking direct skeletal connection between the vertebrae and the pelvis. The phylogenetic positions of the morphotypes were visualized by matching the morphological features onto a novel hypothesis of relationships for the family Balitoridae. The morphotypes determined through skeletal morphology were correlated with patterns observed in the pelvic muscle morphology of these fishes. Transitions towards increasingly robust pelvic girdle attachment were coincident with a more anterior origin on the basipterygium and more lateral insertion of the muscles on the fin rays, along with a reduction of the superficial abductors and adductors with more posterior insertions. These modifications are expected to provide a mechanical advantage for generating force against the ground. Inclusion of the enigmatic cave-adapted balitorid Cryptotora thamicola into the most data-rich balitorid phylogeny reveals its closest relatives, providing insight into the origin of the skeletal connection between the axial skeleton and basipterygium.

A new species of Triplophysa (Cypriniformes, Nemacheilidae) from Weihe River in Gansu Province, China.

A new species of Tibetan loach, Triplophysa weiheensis sp. nov., is described from the Weihe River in Gansu Province, China, based on morphological and molecular analyses. The new species can be distinguished from all known congeners by a unique combination of the following characters: scaleless; snout abruptly sloping downward, anterior to anterior nostril; lower jaw crescentic, not sharp; body without obvious mottling; lateral line interrupted on posterior trunk at pelvic-fin distal extremity; caudal-peduncle length 2.0-2.7 times its depth; branched rays of pectoral fin 10-11; branched rays of pelvic fin 5-6; inner gill rakers on 1 st gill arch 14-16; vertebrae 4+34-36; intestine with 6-7 loops, length ca. 1.8 times SL ( n=3); bony capsule of air bladder small and thin; posterior chamber of air bladder absent.

Resolving an unnoticed diversity within the Schistura robertsi species complex (Teleostei: Nemacheilidae) using molecules and morphology.

The Schistura robertsi species complex is a group of freshwater fish inhabiting streams in southeast Myanmar as well as in western and southern Thailand. In southern Thailand, the distribution exceeds the biogeographically important 'Surat Thani - Krabi line'. The complex is believed to include five described and one undescribed species, but monophyly and systematics of the group have never been studied explicitly. The present study aims to resolve the number of species within the Schistura robertsi group as well as their distribution areas and phylogenetic relations. We analysed mitochondrial and nuclear sequence data of 86 specimens from 47 localities and 18 morphological characters of 193 specimens. The phylogenetic analyses revealed the S. robertsi complex to be monophyletic and to be composed of ten major lineages. Six of them correspond to the known described or undescribed species, but another four newly identified clades reveal the existence of an overlooked diversity within the group. All genetic lineages are statistically highly supported and all are morphologically diagnosable, suggesting that they represent distinct species. The distribution areas of several clades overlap, the cases of direct co-occurrence show no sign of hybridisation.

Asymmetry in the cytoplasm of oocytes of largescale yellowfish Labeobarbus marequensis Smith 1841 (Teleostei: Cypriniformes: Cyprinidae).

The ovaries of the largescale yellowfish, Labeobarbus marequensis (Teleostei: Cypriniformes: Cyprinidae), are made up of the germinal epithelium, nests of late chromatin nucleolus stage oocytes, and ovarian follicles. Each follicle is composed of a single oocyte, which is surrounded by somatic follicular cells and a basal lamina covered by thecal cells. We describe polarization and ultrastructure of oocytes during the primary growth stage. The oocyte nucleus contains lampbrush chromosomes, nuclear bodies and fibrillar material in which multiple nucleoli arise. Nuage aggregations composed of material of a nuclear origin are present in the perinuclear cytoplasm. The Balbiani body (Bb) contains aggregations of nuage, rough endoplasmic reticulum, individual mitochondria and complexes of mitochondria with nuage (cement). Some mitochondria in the Bb come into close contact with endoplasmic reticulum cisternae and vesicles that contain granular material. At the start of primary growth, the Bb is present in the cytoplasm close to the nucleus. Next, it expands towards the oocyte plasma membrane. In these oocytes, a spherical structure, the so-called yolk nucleus, arises in the Bb. It consists of granular nuage in which mitochondria and vesicles containing granular material are immersed. Later, the Bb becomes fragmented and a fully grown yolk nucleus is present in the vegetal region. It contains numerous threads composed of granular nuage, mitochondria, lysosome-like organelles and autophagosomes. We discuss the formation of autophagosomes in the cytoplasm of primary growth oocytes. During the final step of primary growth, the cortical alveoli arise in the cytoplasm and are distributed evenly. The eggshell is deposited on the external surface of the oocyte plasma membrane and is made up of two egg envelopes that are pierced by numerous pore canals. The external egg envelope is covered in protuberances. During primary growth no lipid droplets are synthesized or stored in the oocytes.

Morphological variation associated with trophic niche expansion within a lake population of a benthic fish.

Ecological theory suggests that generalist species should have traits with multiple adaptive peaks. Consequently, in heterogeneous environments such adaptive landscapes may lead to phenotypic divergence that becomes fixed in populations via reproductive isolation, thus driving speciation. However, contrary to this expectation, the process of ecological diversification in wild populations is not always associated with obvious trait divergence and reproductive isolation due to some ecological and geographic constrains. To examine the ecological conditions that promote (or inhibit) divergence is quite important to improve our understanding of the underlying mechanisms. Here we examine how the patterns of trait variation (divergence/non-divergence) are determined in relation to ecological niche expansion and gene flow using a benthic fish, Pseudogobio esocinus, in the Lake Biwa system, Japan. The fish exhibited various patterns of morphological variation in mouth parts among populations. Lake fish tended to have a smaller mouth compared with river fish and also showed remarkable individual variations within some local samples. Lake fish utilized chironomid larvae as the primary prey, as in riverine fish. But, fish with smaller and narrower mouths utilized significantly higher proportions of amphipods (a novel prey unique to the lake) as their secondary prey. Microsatellite analysis detected no genetic structuring in the Lake Biwa catchment, suggesting no reproductive separation among eco-morphologically divergent individuals. Our results exemplify population niche expansion associated with continuous eco-morphological variation without divergence, and provide insights into the role of non-discrete diversification for thriving in heterogeneous environments.

Psilorhynchus nahlongthai, a new fish species (Teleostei: Psilorhynchidae) from the Brahmaputra drainage, northeast India.

Psilorhynchus nahlongthai, a new psilorhynchid fish, is described from the Diyung River, a tributary to the Kopili River (itself a southern tributary of the Brahmaputra drainage) in Assam, northeast India. It is placed in the Psilorhynchus balitora species group and can be easily distinguished from all other members of this group by a combination of the following characters: dense and prominent tuberculation on the head region; thick and long pre- and post-epiphyseal fontanelles on the neurocranium; 9 + 8 caudal-fin rays; and 34 (24 + 10) vertebrae. Genetic divergence between P. nahlongthai and members of the P. balitora species group from the Brahmaputra and neighbouring drainages, with K2P distances ranging 3.7%-14.7% and 7.4%-20.7% in the mitochondrial COI and cyt b gene datasets respectively, support its report as a new species.

Oreonectes guilinensis (Teleostei, Cypriniformes, Nemacheilidae), a new loach species from Guangxi, China.

A new loach Oreonectes guilinensis sp. nov. is described from Guangxi Zhuang Autonomous Region, China. It is the second surface-dwelling fish identified in the genus Oreonectes after the type species Oreonectes platycephalus. This new species can be distinguished from other species within the genus by the combination of the following features: a round caudal fin, 13-14 branched rays, an incomplete lateral line with 4-6 pores, a short pelvic fin located some distance from the anus, a scale-covered body, a stout build (body width 14.0%-16.7% of standard length), a posterior chamber of well-developed airbladder and a yellowish-brown body with a lateral dark brown strip. The maximum likelihood phylogenetic analysis based on cytb gene recovered this new species in a well-supported clade with the type species O. platycephalus, sister to the Lefua clade. Morphological comparisons as well as our phylogenetic tree support Oreonectes shuilongensis, Oreonectes daqikongensis, Oreonectes jiarongensis as species of Troglonectes. Based on our results there are 6 valid species in the genus Oreonectes.

Histology and structural integration of the major morphologies of the Cypriniform Weberian apparatus.

The Weberian apparatus, a diagnostic feature of otophysan fishes, is a novel hearing adaptation integrating several developmental and morphological systems (ear-vertebral column-swim bladder). Otophysan fishes are one of the largest and most successful freshwater clades, with over 10,000 species across most continents. The largest otophysan order, Cypriniformes, dominates the freshwaters of Asia, Europe, North America, and Africa. Spanning such a wide variety of environments, the Weberian apparatus undergoes morphological modifications to maintain functionality. Within Cypriniformes, we propose three distinct morphological classes of the Weberian apparatus based on the level of skeletal expansion around the swim bladder: simple (typical of most Cyprinidae), anterior plate (found in families such as Gyrinocheilidae, Catostomidae, and Botiidae), and encapsulated (either single-capsule as found, e.g., in Gobionidae and Cobitidae, or double-capsule as found, e.g., in Nemacheilidae and Balitoridae). Little ontological or comparative data exists regarding the construction or integration of these different morphologies, and less is known about the tissue level integration and variation within these morphologies. We used paraffin histology to document the hard and soft tissue anatomy of the Weberian apparatus in six species representing all morphological classes. We found sites of similarity across the morphologies including size and structure of the saccule, aspects of ossicle ossification, and swim bladder tunica composition, indicating potential sites of developmental and functional constraint. In contrast, we found differences across both auditory and nonauditory features in otic chamber size, ossification within ossicles and other vertebral elements, and composition of ligaments, indicating likely sites of adaptability. Some of these changes are likely evolutionary (taxonomic), but may be influenced by the environmental niche occupied by the clade. These results show a clear need for increased ontological and comparative study of the complete cypriniform Weberian apparatus, particularly histologically, as well as increased auditory studies across morphological types.