Teleost Family Research Articles

A new rainbow gudgeon of Sarcocheilichthys (Teleostei: Cyprinidae) from Fujian Province, China with redescriptions of S. hainanensis

The teleostean family Cyprinidae is a megadiverse fish taxon that occupies most of the freshwater biomes of the world. The cyprinid genus Sarcocheilichthys of the subfamily Gobioninae is represented by a total of 14 nominal species, most of which are distributed in the vast continent of China. Our recent field collections and surveys in river systems of Fujian Province, southern China, had discovered a cyprinid fish that was recognized herein as a Sarcocheilichthys species new to science. The undescribed species, temporarily known as the Hanjiang rainbow gudgeon, is most similar to S. nigripinnis but can be well distinguished by differences in meristic counts, dorsal fin blotch patterns, and the morphology of oromandibular structures and genital organs. A detailed redescription of the valid Hainan rainbow gudgeon, S. hainanensis, is also provided herein.

Meta-analysis of gonadal transcriptome provides novel insights into sex change mechanism across protogynous fishes.

Protogyny, being capable of changing from female to male during their lifetime, is prevalent in 20 families of teleosts but is believed to have evolved within specific evolutionary lineages. Therefore, shared regulatory factors governing the sex change process are expected to be conserved across protogynous fishes. However, a comprehensive understanding of this mechanism remains elusive. To identify these factors, we conducted a meta-analysis using gonadal transcriptome data from seven species. We curated data pairs of ovarian tissue and transitional gonad, and employed ratios of expression level as a unified criterion for differential expression, enabling a meta-analysis across species. Our approach revealed that classical sex change-related genes exhibited differential expression levels between the ovary and transitional gonads, consistent with previous reports. These results validate our methodology's robustness. Additionally, we identified novel genes not previously linked to gonadal sex change in fish. Notably, changes in the expression levels of acetoacetyl-CoA synthetase and apolipoprotein Eb, which are involved in cholesterol synthesis and transport, respectively, suggest that the levels of cholesterol, a precursor of steroid hormones crucial for sex change, are decreased upon sex change onset in the gonads. This implies a potential universal influence of cholesterol dynamics on gonadal transformation in protogyny.

Microbial Communities Associated with the Intestinal Tract of Grey Mullets from a Mediterranean Aquatic Environment

Introduction: Grey mullets comprise different species that represent the most ubiquitous teleost families in the planet’s coastal waters. They are an important proportion of the Mediterranean lagoon’s production and have been recently considered cultivated marine fish. This study aimed to explore the intestinal microbial communities of grey mullets to understand their possible ecological role for fish and the aquatic environment. Methods: Thirty-four wild-caught mullets were sampled from a Mediterranean lagoon during four seasons and the V3-V4 hypervariable regions of 16S rRNA (Illumina MiSeq) of the fish gut were sequenced. Parameters of the aquatic environment were detected: temperature, salinity, DO, PO4, NH4, NO3, NO2, SiO, DIN, and Chla. Results: The results indicated a high bacterial diversity (mean Shannon index: 4.74 ± 1.12; Simpson index: 0.93 ± 0.08) and variations among seasons. Sixty prokaryotic phyla were identified and the most abundant ones were: Proteobacteria (mean relative abundance 35.4% ± 17.9), Actinobacteriota (mean relative abundance 16.4% ± 9.9), and Firmicutes (mean relative abundance 10.1% ± 10.9). Bacteria belonging to the phylum Chloroflexi were relevant in autumn, Spirochaetota, Verrucomicrobiota, Fusobacteriota, and Cyanobacteria were particularly abundant in winter while Bacteroidota characterized summer fish. A total of 332 prokaryotic families were identified with 26 most abundant ones; Rhodociclaceae (Proteobacteria) were dominant in autumn, Brevinemataceae (Spirocheaetota) and Fusobacteriaceae (Fusobacteriota) were especially present in winter and the Staphylococcaceae (Firmicutes) prevailed in spring. Conclusion: This study sheds light on the variation in the complex gut microbial community structure of Mediterranean grey mullets and their potential ecological role in protecting fish and preserving the aquatic environment.

The spotted parrotfish genome provides insights into the evolution of a coral reef dietary specialist (Teleostei: Labridae: Scarini: Cetoscarus ocellatus).

With over 600 valid species, the wrasses (family Labridae) are among the largest and most successful families of the marine teleosts. They feature prominently on coral reefs where they are known not only for their impressive diversity in colouration and form but also for their functional specialisation and ability to occupy a wide variety of trophic guilds. Among the wrasses, the parrotfishes (tribe Scarini) display some of the most dramatic examples of trophic specialisation. Using abrasion-resistant biomineralized teeth, parrotfishes are able to mechanically extract protein-rich micro-photoautotrophs growing in and among reef carbonate material, a dietary niche that is inaccessible to most other teleost fishes. This ability to exploit an otherwise untapped trophic resource is thought to have played a role in the diversification and evolutionary success of the parrotfishes. In order to better understand the key evolutionary innovations leading to the success of these dietary specialists, we sequenced and analysed the genome of a representative species, the spotted parrotfish (Cetoscarus ocellatus). We find significant expansion, selection and duplications within several detoxification gene families and a novel poly-glutamine expansion in the enamel protein ameloblastin, and we consider their evolutionary implications. Our genome provides a useful resource for comparative genomic studies investigating the evolutionary history of this highly specialised teleostean radiation.

The effects of primary and secondary bacterial exposure on the seahorse (Hippocampus erectus) immune response

Evolutionary adaptations in the Syngnathidae teleost family (seahorses, pipefish and seadragons) culminated in an array of spectacular morphologies, key immune gene losses, and the enigmatic male pregnancy. In seahorses, genome modifications associated with immunoglobulins, complement, and major histocompatibility complex (MHC II) pathway components raise questions concerning their immunological efficiency and the evolution of compensatory measures that may act in their place. In this investigation heat-killed bacteria (Vibrio aestuarianus and Tenacibaculum maritimum) were used in a two-phased experiment to assess the immune response dynamics of Hippocampus erectus. Gill transcriptomes from double and single-exposed individuals were analysed in order to determine the differentially expressed genes contributing to immune system responses towards immune priming. Double-exposed individuals exhibited a greater adaptive immune response when compared with single-exposed individuals, while single-exposed individuals, particularly with V. aestuarianus replicates, associated more with the innate branch of the immune system. T. maritimum double-exposed replicates exhibited the strongest immune reaction, likely due to their immunological naivety towards the bacterium, while there are also potential signs of innate trained immunity. MHC II upregulated expression was identified in selected V. aestuarianus-exposed seahorses, in the absence of other pathway constituents suggesting a possible alternative or non-classical MHC II immune function in seahorses. Gene Ontology (GO) enrichment analysis highlighted prominent angiogenesis activity following secondary exposure, which could be linked to an adaptive immune process in seahorses. This investigation highlights the prominent role of T-cell mediated adaptive immune responses in seahorses when exposed to sequential foreign bacteria exposures. If classical MHC II pathway function has been lost, innate trained immunity in syngnathids could be a potential compensatory mechanism.

Molecular characterization and expression analysis of nine toll like receptor (TLR) genes in Scortum barcoo under Streptococcus agalactiae infection

Toll like receptors (TLRs) are important pattern recognition receptors participating in innate immune system. Up to now, no TLR has been identified in Jade perch (Scortum barcoo). In this study, we successfully identified 9 members of TLRs from the Jade perch. Amino acid sequence alignment analysis showed that the whole sequences of these TLRs were highly conserved among different fish species, especially in LRR, TM and TIR domains. Phylogenetic analysis revealed that each SbTLR was successfully grouped into corresponding gene family of teleosts. Expression analysis showed that most SbTLRs mainly expressed in liver, spleen, muscle and skin, while expressed less in brain and stomach. After Streptococcus agalactiae infection, expression of SbTLR2, SbTLR5S and SbTLR22 were significantly upregulated, while SbTLR3, SbTLR5M, SbTLR9, SbTLR13, and SbTLR14 were significantly downregulated. In all, this research first reported molecular characterization and expression profiles of 9 TLRs in Jade perch. These data will make a contribution for better understanding the antibacterial mechanism of TLRs in teleosts.

Ocorrência de hiperostose na guaivira, Oligoplites saurus (Bloch and Schneider, 1801) de águas costeiras brasileiras

ABSTRACT Hyperostotic bones occur in several families of marine teleosts, however there are few reports on its development in fish from Brazilian waters. The present study identified the occurrence of hyperostosis in specimens of Leatherjacket fish Oligoplites saurus, an important commercial species, using radiographic images. Biometric measurements of four specimens were performed and the affected bones were detected in different levels and regions of the skeleton: Supraoccipital, Pterygiophores, Cleithrum, Hemal Spines and Neural Spines. Bones with hyperostosis represented up to 7% of the weight of the eviscerated fish. The pattern found was consistent with previous reports in the literature for other species of the genus Oligoplites, this being the first report of hyperostosis for O. saurus.

Lionfish Diet Composition at Three Study Sites in the Aegean Sea: An Invasive Generalist?

The diet of the lionfish (Pterois miles), an invasive species in the Aegean Sea, was examined by collecting stomach content data from fish collected in three study sites in the Aegean Sea (southern Crete, Kastellorizo, and Nysiros islands). Prey composition in terms of numerical abundance and frequency of occurrence was used to compare lionfish’s diet between these sites. Lionfish largely preyed upon teleosts (4% to 83% numerical abundance and 16% to 58% frequency of occurrence, depending on the site) and decapods (12% to 95% numerical abundance and 11% to 81% frequency of occurrence). The most important teleost families in lionfish’s diet were Gobiidae, Labridae, and Scorpaenidae, while decapods and especially the family Scyllaridae and the genus Plesionika were the dominant decapod prey items. The lionfish was found to be an especially successful generalist across the study sites, an opportunistic, predatory species overall, and at the same time, at a local level, it seems to be an equally successful specialist that could increase the predation mortality of already stressed prey populations and can be a serious threat to endemic, critically endangered, and/or commercially important species.

The squaretail mullet Ellochelon vaigiensis (Quoy & Gaimard, 1825) a complex of cryptic species?

Abstract The teleost family Mugilidae is speciose with uniform morpho-anatomical characteristics, which render species identification difficult. The dna barcoding technique has, however, proven to be a precise and reliable approach for species delineation. To date, dna barcoding flags numerous polyphyletic species in Mugilidae that probably correspond to species complexes and that call for further taxonomical investigation. Among these species, the squaretail mullet Ellochelon vaigiensis is an interesting case study because, unlike other mullet species, it is easily identified from its unique phenotype. Recent studies of genetic diversity in this monotypic species have revealed two lineages, located either in the Indo-Pacific (Polynesia and Taiwan waters) or along Australian shores. In this study, a third lineage is described in the North of the Indian Ocean, based on nucleotide polymorphisms of Cytochrome c oxidase 1 and barcodes available in bold and Cytochrome b. Despite genetic divergences that exceed the intraspecific threshold, there was no morpho-anatomical difference among specimens of the north Indian Ocean vs. Indo-Pacific or Australia. These molecular results suggest nominal species of Ellochelon vaigiensis within a cryptic species complex.

Characterization of ddx4 and dnd Homologs in Snakeskin Gourami (Trichopodus pectoralis) and Their Expression Levels during Larval Development and in Gonads of Males and Females.

The purpose of this study was to clone and characterize ddx4 and dnd1 homologs in snakeskin gourami (Trichopodus pectoralis) and to determine their expression levels during larval development and in the gonads of males and females. Both cDNAs contained predicted regions that shared consensus motifs with the ddx4 family in teleosts and the dnd family in vertebrates. Phylogenetic tree construction analysis confirmed that these two genes were clustered in the families of teleosts. Both ddx4 and dnd1 mRNAs were detectable only in the gonads, particularly in germ cells. These two genes were expressed during early larval development. The expression of ddx4 was high during early larval development and decreased with increasing developmental age, whereas dnd1 expression increased with developmental age. In adult fish, the expression levels of both genes were higher in the ovary than in the testis. Overall, these findings provide valuable molecular information on ddx4 and dnd, and can be applied in future reproductive biological studies relating to sex dimorphism in snakeskin gourami.

The uselessness of cytochrome oxydase gene analysis for genetic identification of selected Gobiidae species from some European countries

The family Gobiidae is the largest teleost family, consisting of more than 2,000 species in more than 200 genera. They have adapted to a wide range of habitats, inhabiting mostly marine and brackish waters. Recently invasive Ponto-Caspian gobies have caused significant changes to the structure of fish assemblage throughout the European waters. The aim of the study was to verify the possibility of identifying three species of the genus Gobiidae based on the analysis of the mitochondrial region of the cytochrome oxidase subunit 1 (COI) gene. 339 samples originated from seven countries and 17 different sites were investigated. Qualitative and quantitative assessment of the extracted DNA was conducted by measuring light absorbance and electrophoretic separation. Approximately 650-bp (base pairs) fragments were amplified from the 5' region of the mitochondrial COI with the PCR (polymerase chain reaction) reaction. Sequences of 652 bp were obtained and compared with reference sequences in the National Center for Biotechnology Information (NCBI). Based on the sequence analysis, we determined that in the analysed geographical regions, the goby preliminary identified morphologically as the round goby was represented by three species: round goby ( Neogobius melanostomus), tubenose goby ( Proterorhinus marmoratus), and monkey goby ( Neogobius fluviatilis). The latter two are newly reported for their new habitats. Genetic characterisation of such populations offers the opportunity to assess their genetic stability, which provides agencies managing the aquatic environment in EU countries with a tool for revising the legislation, including regulations relevant for updating the status of native and invasive species in European waters.

FishShapes v1: Functionally relevant measurements of teleost shape and size on three dimensions.

Teleost fishes account for 96% of all fish species and exhibit a spectacular variety of body forms. Teleost lineages range from deep bodied to elongate (e.g., eels, needlefish), laterally compressed (e.g., ribbonfish) to globular (e.g., pufferfish), and include uniquely shaped lineages such as seahorses, flatfishes, and ocean sunfishes. Adaptive body shape convergence within fishes has long been hypothesized but the nature of the relationships between fish form and ecological and environmental variables remain largely unknown at the macroevolutionary scale. To facilitate the investigation of the interacting factors influencing teleost body shape evolution we measured eight functionally relevant linear traits on adult-sized specimens along with specimen mass. Linear measurements of standard length, maximum body depth, maximum fish width, lower jaw length, mouth width, head depth, minimum caudal peduncle depth, and minimum caudal peduncle width were taken in millimeters with calipers, or tape measures for oversized specimens. We measured these traits on a total of 16,523 specimens (1-3 specimens per species) at the Smithsonian National Museum of Natural History and took approximately 7000 person hours of data collection to complete. The data went through a three-step error-checking process to clean and validate the data and then species averages were calculated. We present the complete specimen data set, which encompasses approximately one-fifth of extant teleost species diversity, spanning ~90% of teleost families and ~96% of orders. The species and family names are compatible with the taxonomy used by FishBase and the order information with the phylogenetically informed taxonomy of Betancur-R and colleagues published in 2014. This dataset is licensed under Creative Commons CC0 1.0 Universal (CC0 1.0) but please cite this paper when using the data or a subset of it.

An atlas of fish genome evolution reveals delayed rediploidization following the teleost whole-genome duplication.

Teleost fishes are ancient tetraploids descended from an ancestral whole-genome duplication that may have contributed to the impressive diversification of this clade. Whole-genome duplications can occur via self-doubling (autopolyploidy) or via hybridization between different species (allopolyploidy). The mode of tetraploidization conditions evolutionary processes by which duplicated genomes return to diploid meiotic pairing, and subsequent genetic divergence of duplicated genes (cytological and genetic rediploidization). How teleosts became tetraploid remains unresolved, leaving a fundamental gap in the interpretation of their functional evolution. As a result of the whole-genome duplication, identifying orthologous and paralogous genomic regions across teleosts is challenging, hindering genome-wide investigations into their polyploid history. Here, we combine tailored gene phylogeny methodology together with a state-of-the-art ancestral karyotype reconstruction to establish the first high-resolution comparative atlas of paleopolyploid regions across 74 teleost genomes. We then leverage this atlas to investigate how rediploidization occurred in teleosts at the genome-wide level. We uncover that some duplicated regions maintained tetraploidy for more than 60 million years, with three chromosome pairs diverging genetically only after the separation of major teleost families. This evidence suggests that the teleost ancestor was an autopolyploid. Further, we find evidence for biased gene retention along several duplicated chromosomes, contradicting current paradigms that asymmetrical evolution is specific to allopolyploids. Altogether, our results offer novel insights into genome evolutionary dynamics following ancient polyploidizations in vertebrates.

A new Cardiodectes Wilson, 1917 (Hexanauplia: Copepoda: Siphonostomatoida) parasitic on a scarid teleost (Perciformes: Scaridae) from Roatan Island, Central America.

Members of the parasitic copepod family Pennellidae are highly transformed ecto- or mesoparasites infecting a wide array of marine teleosts. Currently, this family contains more than 20 valid genera. The pennellid genus Cardiodectes Wilson, 1917 is currently known to contain 15 nominal species. Some pennellids exhibit a complex life cycle involving an intermediate host; it is known that planktonic pteropod molluscs are intermediate hosts for Cardiodectes. Pennellid mesoparasites can be detected by the conspicuous female egg-carrying trunk on the host external surface. The copepod cephalothorax is deeply embedded in the host muscle tissue. Members of Cardiodectes have been reported from several teleost families, mainly Myctophidae and Engraulidae. From the parasitological examination of a juvenile individual of a scarid teleost collected in a reef lagoon of Roatan Island, Honduras, Central America, several ovigerous female individuals of a mesoparasitic pennellid copepod were found; these specimens were recognized as representative of an undescribed species ofCardiodectes Wilson, 1917. The new species,C. roatanensis n. sp., differs from its known congeners in several respects, including the presence of neck lobes, paired posterior protuberances of the trunk, trunk shape and proportions, structure of cephalothorax lobes, cephalothorax relative size, and number of legs. The new species from Roatan is the second member of this copepod genus to be reported from the Caribbean region, after C. boxshalli Bellwood, 1981 from off Jamaica (Bellwood 1981). It is also the second report of Cardiodectes on a parrotfish.

Quantification and comparison of teleost scleral cartilage development and growth.

The ocular skeleton is composed of the scleral cartilage and the scleral ossicles. Teleost scleral cartilage is composed of a single layer of chondrocytes embedded in the sclera of the eye. The teleost scleral cartilage ring can vary in depth across teleost families and species, from a narrow ring a few cells wide to a deeper ring that resembles a cup and surrounds the entire sclera. However, very little research has been conducted on the development and morphology of teleost scleral cartilage. Thus, this study aims to characterize the development of the scleral cartilage in the zebrafish and Mexican tetra, with respect to the timing of emergence, depth throughout development, and positioning within the eye. We hypothesized that the scleral cartilage would first emerge in the scleral tissue closely abutting the ora serrata, and that growth would proceed in an anterior-to-posterior direction, resulting in differences in scleral cartilage depth between different fish species. We found that the scleral cartilage ring does not develop uniformly along its circumference, and that its relationship to the ora serrata varies between the rostral and caudal regions. Furthermore, distinct differences in the growth trajectory of the scleral cartilage indicate that the deep scleral cartilage of the Pachón cavefish is the result of both decreased eye size and prolonged cartilage growth. A significant difference in the size of the scleral chondrocytes was also noted. Overall, this study provides the first characterization of early scleral cartilage development in teleost fish and indicates that some aspects of scleral cartilage development and morphology are highly conserved while others are not.

Biology and ecology of lionfish (Pterois volitans) in the Corales de Profundidad Natural National Park, Colombian Caribbean

Lionfish was studied in the mesophotic environment. 237 specimens were observed, most in the upper mesophotic zone. Males were larger than females and differences between sexes in growth models were found. Sixteen prey items were identified, the most important being the teleost families Acanthuridae and Monacanthidae, and the crustacean Penaeidae. The mean of δ13C was -17.08 ± 0.36 ‰ and δ15N was 8.68 ± 0.46 ‰, with no differences between sexes. Lionfish occupies a less extensive isotopic niche in mesophotic environment than in shallow sectors; there is an isotopic niche overlap between sexes. Likewise, lionfish has specialized trophic habits. All specimens were mature and in females regression phase predominated. In females, condition factor (CF), gonadosomatic index (GSI) and hepatosomatic index (HSI) increased with gonadal development, reaching peak in the active spawning phase, and decreasing in regression. Males had a condition factor similar to spawning females, but IGS and IHS were lower

Morphological and molecular characterization of the marine-teleost parasitizing acanthocephalan Echinorhynchus hexagrammi (Syndermata: Palaeacanthocephala) from a new host, Liparis sp. (Actinopterygii: Scorpaeniformes).

Originally described from the masked greenling Hexagrammos octogrammus (Pallas, 1814), the palaeacanthocephalan Echinorhynchus hexagrammi Baeva, 1965 has so far been known from seven species in six families of marine teleosts distributed in the Sea of Okhotsk off Sakhalin and in the Northwestern Pacific off Hokkaido, Japan. In this study, we examined the phylogenetic position of E. hexagrammi based on material obtained from the intestine of an unidentified snailfish, Liparis sp., dredged in Akkeshi Bay, Hokkaido, Japan. We performed an analysis using two gene markers, the mitochondrial cytochrome c oxidase subunit I and the nuclear 28S rRNA, along with other sequences available in public databases. In the resulting tree, E. hexagrammi was more closely related to two species complexes, the E. bothniensis Zdzitowiecki and Valtonen, 1987 complex and the E. gadi Zoega in Müller, 1776 complex, rather than to E. brayi Wayland, Sommerville, and Gibson, 1999, E. cinctulus (Porta, 1905), E. salmonis Müller, 1784, and E. truttae Schrank, 1788. The morphology of the examined material herein identified as E. hexagrammi is briefly described. This study represents the first host record of E. hexagrammi from the snailfish family Liparidae.

Genome and gene evolution of seahorse species revealed by the chromosome-level genome of Hippocampus abdominalis.

Seahorses belong to the teleost family Syngnathidae that evolved a distinct body plan and unique male pregnancy compared to other teleosts. As a classic model for studying evolution of viviparity and sexual selection of teleosts, seahorse species still lack a publicly available high‐quality reference genome. Here, we generated the genome assembly of the big‐belly seahorse, Hippocampus abdominalis with long‐read and Hi‐C technologies. We managed to place over 99% of the total length of 444.7 Mb of assembled genome into 21 linkage groups with almost no gaps. We reconstructed a phylogenomic tree with the big‐belly seahorse genome and other representative Syngnathidae and teleost species. We also reconstructed the historical population dynamics of four representative Syngnathidae species. We found the gene families that underwent expansion or contraction in the Syngnathidae ancestor were enriched for immune‐related or ion transporter gene ontology terms. Many of these genes were also reported to show a dynamic expression pattern during the pregnancy stages of H. abdominalis. We also identified putative positively selected genes in the Syngnathidae ancestor or in H. abdominalis, whose mouse mutants are enriched for abnormal craniofacial and limb morphological phenotypes. Overall, our study provides an important genome resource for evolutionary and developmental studies of seahorse species, and candidate genes for future experimental works.

Interferon Gamma Induces the Increase of Cell-Surface Markers (CD80/86, CD83 and MHC-II) in Splenocytes From Atlantic Salmon.

Type II interferon gamma (IFNγ) is a pleiotropic cytokine capable of modulating the innate and adaptive immune responses which has been widely characterized in several teleost families. In fish, IFNγ stimulates the expression of cytokines and chemokines associated with the pro-inflammatory response and enhances the production of nitrogen and oxygen reactive species in phagocytic cells. This work studied the effect of IFNγ on the expression of cell-surface markers on splenocytes of Atlantic salmon (Salmo salar). In vitro results showed that subpopulations of mononuclear splenocytes cultured for 15 days were capable of increasing gene expression and protein availability of cell-surface markers such as CD80/86, CD83 and MHC II, after being stimulated with recombinant IFNγ. These results were observed for subpopulations with characteristics associated with monocytes (51%), and features that could be related to lymphocytes (46.3%). In addition, a decrease in the expression of zbtb46 was detected in IFNγ-stimulated splenocytes. Finally, the expression of IFNγ and cell-surface markers was assessed in Atlantic salmon under field conditions. In vivo results showed that the expression of ifnγ increased simultaneously with the up-regulation of cd80/86, cd83 and mhcii during a natural outbreak of Piscirickettsia salmonis. Overall, the results obtained in this study allow us to propose IFNγ as a candidate molecule to stimulate the phenotypic progression of a small population of immune cells, which will increase antigen presenting cells markers. Thereby, modulatory strategies using IFNγ may generate a robust and coordinated immune response in fish against pathogens that affect aquaculture.

Phylogenetic position and relationships of mountain loaches (Teleostei: Balitoridae) of the Western Ghats as revealed by CO1 sequences.

The teleostean family Balitoridae comprises small-sized freshwater fishes adapted to swift-flowing torrential mountain streams in South and South-East Asia. Little is known about their molecular phylogenetics and evolutionary biogeography, and much of the scientific literature that references them is focused on morphological taxonomy. In this paper, we generate CO1 sequences for the endemic balitorid lineages of the Western Ghats (WG) Hotspot in India, particularly for the endemic genera, Bhavania, Ghatsa and Travancoria. Integration of these data into a phylogeny revealed that the endemic WG genera together form a well-supported monophyletic clade that shows, subject to our limited taxon sampling, a sister-group relationship to the Southeast Asian genus Pseudohomaloptera. Three WG endemic species of the genus Balitora, namely B. chipkali, B. jalpalli and B. laticauda, though morphologically distinct, have low genetic divergence and barcode gap, suggestive of recent speciation. Interestingly, a fourth WG endemic, B. mysorensis, formed a clade with two species of Balitora from Eastern-Himalaya and Indo-Burma. We also show that all available CO1 sequences assigned to WG endemic balitorid genera in GenBank are misidentifications, and provide diagnostic characters for the accurate identification of these taxa in the future.