First records of Osteochilus flavicauda Kottelat & Tan, 2009 (Cypriniformes, Cyprinidae, Labeoninae) from Indonesia

the journal of biodiversity data NOTES ON GEOGRAPHIC DISTRIBUTION 1092 Academic editor: Bakhtiyor Sheraliev Received: 18 September 2025 Accepted: 30 October 2025 Published: 11 November 2025 Copyright © The authors. This is an open‑access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0) Abstract. Two specimens of Osteochilus flavicauda were found in 2023 from Bangka Island and Belitung Island, within the Bangka‑Belitung Islands Province, Indonesian Archipelago. These specimens represent the first record of the species from Indonesian islands and the country. These new records extend the known geographic range to the southeast, beyond the mainland sites of Johor, Malaysia, and Pattani, Thailand. These findings represent a significant range extension and contribute to the understanding of the ichthyo‑ fauna in undersampled regions of Sundaland. Key words. Bangka‑Belitung Province, biogeography, Indonesian Archipelago, new record, Sundaland Hasan V, Oliveira RF, Filgueira CTS, Syarif AF, Valen FS, Kamarudin AS, Ahmad AB, Samitra D, South J, Ottoni FP (2025) First records of Osteochilus flavicauda (Cypriniformes, Cyprinidae, Labeoninae) from Indonesia. Check List 21 (6): 1092–1098. https://doi.org/10.15560/21.6.1092 INTRODUCTION Osteochilus Günther, 1868 is a genus of cyprinid fish (Cypriniformes, Cyprinidae, Labeoninae), currently com‑ prising approximately 30 valid species distributed throughout South and Southeast Asia, including India, Myanmar, Laos, Thailand, Malaysia, Indonesia, and southern China (Fricke et al. 2025a, 2005b; Froese and Pauly 2025). Species of this genus are primarily found in lotic environments and are morphologically charac‑ terized by a subterminal mouth and thick, folded lips, adaptations associated with scraping and adhering to substrates in moderate to fast‑flowing freshwater habitats (Karnasuta 1993; Yang et al. 2012). Osteochilus flavicauda Kottelat & Tan, 2009 is a relatively recently described species, which is endemic to the Malay Peninsula and more specifically from Peninsular Thailand and Malaysia (Johor) (Kottelat and Tan 2009; Ahmad 2019; Fricke et al. 2025b). It is morphologically similar to O. microcephalus (Valenciennes 1842) and shares with it a black midlateral stripe (Kottelat and Tan 2009). Specimens exhibiting, in life or when re‑ cently preserved, a yellow caudal fin, instead of a red one, were previously misidentified as O. microcephalus. Upon re‑examination of this species complex, Kottelat and Tan (2009) recognized those specimens with a yellow caudal fin as representing a distinct species and described them as O. flavicauda. Osteochilus flavicauda is listed as Least Concern in the IUCN Red List (Ahmad 2019; Fricke et al. 2025b). At the time of its description, this species was regarded as endemic to the eastern drainages of the Malay Peninsula, with confirmed records from rivers in Johor (Malaysia) and southern Thailand (Pattani) (Ahmad 2019; Fricke et al. 2025b). It has not been recorded from the west coast of the peninsula nor from Indonesian territory, including Sumatra, Borneo, or other islands of the Indonesian archipelago (Kottelat and Tan 2009). In this study, we report the first confirmed record of O. flavicauda for Indonesia, based on specimen collected from Bangka and Belitung Islands. This new record represents a significant geographic range ex‑ tension of the known distribution of the species and contributes to the understanding of the ichthyofauna in undersampled regions of Sundaland. We provide photographs of the collected specimen, a distribution map, and notes on habitat and observed morphological features. 21 (6) · https://doi.org/10.15560/21.6.1092 21 (6): 1092–1098. https://doi.org/10.15560/21.6.1092 First records of Osteochilus flavicauda Kottelat & Tan, 2009 (Cypriniformes, Cyprinidae, Labeoninae) from Indonesia Veryl Hasan1, 2, Rafael F. Oliveira3, Carlos Thiago S. Filgueira3, 4, Ahmad F. Syarif5, Fitri S. Valen5, Ahmad S. Kamarudin2, Amirrudin B. Ahmad6, Dian Samitra7, Josie South8, Felipe P. Ottoni3, 4, 9 1 Department of Aquaculture, Faculty of Fisheries and Marine, Universitas Airlangga, Surabaya 60115, East Java, Indonesia 2 School of Animal Science, Aquatic Science and Environment, Universiti Sultan Zainal Abidin, Besut Campus, Besut 22200, Terengganu, Malaysia 3 Universidade Federal do Maranhão, Laboratório de Sistemática e Ecologia de Organismos Aquáticos, Chapadinha, Maranhão, Brazil 4 Universidade Federal do Maranhão, Programa de Pós-Graduação em Ciências Ambientais, Chapadinha, Maranhão, Brazil 5 Department of Aquaculture, Agriculture, Fisheries and Marine Faculty, Universitas Bangka Belitung, Balunijuk 33127, Bangka Belitung, Indonesia 6 Institute of Tropical Biodiversity and Sustainable Development, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia 7 Department of Biology Education, Faculty of Science and Technology, Universitas PGRI Silampari, Lubuklinggau, 31625, Indonesia 8 School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom 9 NRF-South African Institute for Aquatic Biodiversity (NRF-SAIAB), P. Bag 1015, Makhanda 6140, South Africa Corresponding author: Veryl Hasan ([email protected].ac.id) Check List 21 (6) · https://doi.org/10.15560/21.6.1092 Hasan et al. · First records of Osteochilus flavicauda for Indonesia 1093 METHODS In Badau Subdistrict, Belitung District, Belitung Island, within the Bangka‑Belitung Islands Province, Indone‑ sia, on 12 May 2023, several specimens of Osteochilus flavicauda were collected. However, only one specimen was preserved as voucher material (Figure 1a, b), and the remaining specimens were released back into the collecting site. Before these specimens were released, their external features were examined and validated by Veryl Hasan. The vouchered specimen was preserved in 10% formalin for 10 days and subsequently transferred to 70% ethanol for permanent preservation. The specimen is deposited in the Ichthyological Collection of the Natural History Museum of Universitas Airlangga (ANMH), under voucher number ANMH 101. The second specimen refers to a specimen observed and photographed on 12 September 2024 in Cam‑ bai Village, Central Bangka District, Bangka Island, within the Bangka‑Belitung Islands Province, Indonesia (Figure 1c). The specimen was not preserved, but its identification was based on photographs and features useful for species identification (e.g. number of tubercles at the tip of the snout) which was observed and provided by one of the fishermen (MuhammadIlmi) and validated by Veryl Hasan. The photograph valida‑ tion followed the guidelines proposed by Campos et al. (2023), which include the submission of the origi‑ nal, unedited image, associated metadata (date, time, and precise coordinates), and information on image ownership and photographer attribution. A photograph of the specimen, for which researcher Veryl Hasan holds ownership, was provided by local fishermen. The identification of the specimens of O. flavicauda was based both on examined material, on collected specimens that were released back into the collecting site, and on literature (e.g. Kottelat and Tan 2009). Information on the other congeners was based only on literature (e.g. Kottelat and Tan 2009). The identifi‑ cation of the specimens was based on the analysis of external morphological characters, body proportions, and live coloration, as proposed by Kottelat and Tan (2009). Morphometric measurements of the preserved specimen were taken with digital calipers (0.1 mm accuracy) and expressed as percentages of standard length (SL), following standard methodology for Cyprinidae. The distribution map was generated based on previously published records (e.g. Kottelat and Tan 2009; Ahmad 2019; Ahmad et al. 2023), and the two new occurrences reported herein. The base map of the Indonesian Islands was processed using QGIS v. 3.28 and adjusted to match the geographic scale of the occurrence points. RESULTS Osteochilus flavicauda Kottelat & Tan, 2009 Figure 1; Table 1 New records. INDONESIA — Bangka-Belitung islands Province • Belitung Island, Belitung District, Badau Subdistrict, upstream of the Cerucuk River; 02°47′S, 107°51′E; 12.V.2023; V. Hasan leg.; scoop net; 1 ♂, 125.0 mm SL, ANMH 101 • Bangka Island, Central Bangka District, Cambai Village; 02°15′S, 106°09′E; 12 .IX.2024; obs. (photograph provided by local fishermen, validated by V. Hasan); 1 spec. (Figure 1c). Identification. The specimens were identified as O. flavicauda based on the diagnostic morphological features proposed by Kottelat and Tan (2009). According to Kottelat and Tan (2009), O. flavicauda is diag‑ Figure 1. Osteochilus flavicauda. a. Live male. b. Recently preserved male (125 mm SL; voucher ANMH 101), upper Cerucuk River, Belitung Island, within the Bangka‑Belitung Islands Province, Indonesia, 12 May 2023 (photo: V. Hasan). c. Photograph of live specimen provided by local fishermen, Cambai Village, Bangka Island, within the Bangka‑Belitung Islands Province, Indonesia, 12 September 2024 (validated by V. Hasan). Check List 21 (6) · https://doi.org/10.15560/21.6.1092 Hasan et al. · First records of Osteochilus flavicauda for Indonesia 1094 nosed mainly by body moderately deep, dorsal profile strongly arched in front of dorsal fin origin with a concavity at nape. Its ventral profile is arched, but less than dorsal profile. In addition, O. flavicauda share with O. waandersii (Bleeker, 1853) and O. kerinciensis Tan & Kottelat 2009 the presence of a black midlateral stripe ending at the posterior extremity of the median caudal‑fin rays, which distinguish these three species from all other congeners. Osteochilus flavicauda is distinguished from O. waandersii and O. kerinciensis by having a single tubercle at the tip of the snout (vs. three), caudal, anal, pectoral and pelvic fins yellow (vs. red), and midlateral stripe with very contrasted edges, obvious, and continued until eye by a faint grayish patch on opercle (vs. faint, especially anteriorly, with blurry edges, ending at upper extremity of gill opening at level of upper margin of eye). All these diagnostic features mentioned above are present in the photo‑ graphed, collected specimens that were released, and the preserved specimen examined here (Figure 1). To ensure the accurate taxonomic identification of the specimens herein examined, we consulted Dr. Tan Heok Hui (Lee Kong Chian Natural History Museum, Singapore), an expert working on the genus Osteochilus, who confirmed the specimens’ identification as O. flavicauda. Geographic distribution. The presence of Osteochilus flavicauda was previously known from its origi‑ nal description, restricted to Johor State in southern Peninsular Malaysia and Pattani Province in southern Thailand (Kottelat and Tan 2009), and subsequently, the species was also recorded for central Malaysia, specifically in Tasek Bera—a peat‑swamp ecosystem located at 03°05′N, 102°38′E, in the southwestern part of Pahang State, approximately 25.6 km from the nearest town, Bahau, in the neighboring state of Negeri Sembilan (Ahmad et al. 2023). In the present study, we report two additional localities for O. flavicauda, both corresponding to insular sites within the Indonesian Archipelago (Figure 2): the Cerucuk River on Belitung Island and a headwater tributary near Cambai Village on Bangka Island, both within the Bangka‑Belitung Islands Province, Indonesia. These new island records are located approximately 550 km southeast of Pattani (the nearest previously known locality) and demonstrate that the species inhabits both continental and island drainages across the Sundaland region, thereby extending its known geographic range. Ecological notes. At the collecting site on Belitung Island, several specimens of Osteochilus flavicauda were collected in sympatry with Gymnochanda verae Tan & Lim, 2011, an endemic species of Belitung (Fricke et al. 2025b), as well as several other native fishes, including Mastacembelus notophthalmus Roberts, 1989, Barbucca diabolica Roberts, 1989, Rasbora einthovenii (Bleeker, 1851), and Osteochilus spilurus (Bleeker, 1851) (Fricke et al. 2025b). Osteochilus flavicauda was relatively common at this collecting site, although its abun‑ dance was lower than that of the most prevalent species on Belitung Island, such as O. spilurus. At the col‑ Table 1. Morphometric and meristic characters of Osteochilus flavicauda. Present study (ANMH 101) Kottelat and Tan (2009) Holotype Paratypes Morphometric data Standard length – SL (mm) 125.0 96.4 125.3–149.3 Percent of SL Predorsal length 47.2 49.0 44.8–48.0 Preanal length 77.6 77.5 7 7.0–80.3 Prepelvic length 52.8 52.8 50.7–53.8 Head length 23.9 24.7 21.0–23.3 Snouth length 9.9 10.5 8.8–11.0 Eye diameter 4.9 5.8 4.4–4.9 Meristic data Dorsal‑fin rays (unbranched) 4 4 Dorsal‑fin rays (branched) 12½ 12½ Scale at origin above later line 9 8‑9 Anal‑fin rays (unbranched) 3 3 Anal‑fin rays (branched) 5½ 5½ Pelvic‑fin rays 8 8 Caudal‑fin rays (principal rays) 10+9 10+9 Caudal‑fin rays (branched) 9+8 9+8 Lateral line scales 31+2 30–31+2–3 Predorsal scales 10 10 Check List 21 (6) · https://doi.org/10.15560/21.6.1092 Hasan et al. · First records of Osteochilus flavicauda for Indonesia 1095 lecting site on Bangka Island, only a single specimen of O. flavicauda was obtained. It occurred in sympatry with the endemic fighting fishes Betta chloropharynx Kottelat & Ng, 1994 and B. schalleri Kottelat & Ng, 1994 (Fricke et al. 2025b), as well as with Clarias nieuhofii Valenciennes, 1840, M. notophthalmus, and Barbodes sellifer Kottelat & Lim, 2021. The occurrence of O. flavicauda in sympatry with regional endemic species suggests that it is an established component of the native ichthyofauna of the Bangka and Belitung Islands, rather than an accidental introduction. DISCUSSION The new records published here for Osteochilus flavicauda have all the diagnostic features as proposed by Kottelat and Tan (2009 (see identification section for details). Although the second specimen was not phys‑ ically preserved, high‑resolution photographic documentation, along with georeferenced metadata and validation procedures, supports the reliability of the record (Campos et al. 2023). In addition, the remaining specimens collected on Belitung Island, which were released back into the collecting site, had their external features examined and validated by Veryl Hasan. Previously, O. flavicauda was known only from southern Peninsular Malaysia (Johor) and southern Thai‑ land (Pattani), with a later record from central Malaysia in the peat‑swamp ecosystem of Tasek Bera (Kottelat & Tan 2009; Ahmad 2019; Ahmad et al. 2023). Until this study, O. flavicauda was believed to be confined to the eastern drainages of Peninsular Malaysia and the extreme south of Thailand (Kottelat and Tan 2009; Ahmad 2019; Ahmad et al. 2023). The two new records presented here constitute the first confirmed occurrences of O. flavicauda in Indonesia, from Bangka and Belitung Islands, both within the Bangka‑Belitung Islands Prov‑ ince. These findings extend the known geographic range of the species by approximately 550 km south‑ eastward and represent insular occurrences for a species previously considered restricted to continental environments (Figure 2). Given that the species was recorded in two separate localities, both spatially and temporally separated, accidental occurrence is unlikely. Instead, these records indicate the presence of an established population in the Bangka‑Belitung Islands Province, Indonesia (Figure 2). Furthermore, this report represents the first confirmed record of the species for Indonesia. The newly documented sites are mid‑sized lowland streams with clear to slightly tannic water, sand–gravel substrates, and moderate currents, exhibiting physical con‑ ditions comparable to those described from Johor and Pattani (Kottelat and Tan 2009; Ahmad 2019). These records from rivers on Bangka and Belitung islands indicate that viable populations can persist outside the continental Malay Peninsula, in medium‑sized lotic environments with environmental characteristics similar to previously described habitats (Kottelat and Tan 2009; Ahmad, 2019). This environmental similarity sug‑ gests that comparable habitats across the region may also harbor overlooked populations. Consequently, continued sampling in such environments could reveal a broader distribution than previously recognized. These findings, therefore, lend support to recent studies showing that the ichthyofauna of the Sunda Archi‑ Figure 2. Known distribution of Osteochilus flavicauda in Sundaland. Black triangles = literature records from the Malay Peninsula and Thailand based on Kottelat and Tan, (2009), Ahmad (2019) and Ahmad et al. (2023); and red stars = new insular records from Bangka‑Belitung Islands Province, Indonesia reported in this study. Check List 21 (6) · https://doi.org/10.15560/21.6.1092 Hasan et al. · First records of Osteochilus flavicauda for Indonesia 1096 pelago islands remains undersampled (Hasan et al. 2023a), with considerable gaps in the documentation of freshwater fish diversity (Hutama et al. 2016). This pattern underscores the need for renewed field surveys and a critical taxonomic reassessment of presumed endemism in the region. From a biogeographic perspective, the occurrence of O. flavicauda on Bangka Island and Belitung Islands, within the Bangka‑Belitung Islands Province, Indonesia, probably reflects the connectivity of pa‑ leodrainages during Pleistocene periods of lower sea level, when land bridges linked Sumatra, Borneo, and the Malay Peninsula across the Sunda Shelf (Voris 2000; Pubellier and Morley 2014). Phylogeographic studies support this idea. For example, populations of Osteochilus vittatus (Valenciennes, 1842) from Sumatra with the northern Sunda paleo‑system, those from Malaysia align with the Malacca system, and those from Java and Borneo cluster with the eastern Sunda system (Imron et al. 2024). Genetic similarity between eastern Peninsular Malaysian and Sumatran populations has likewise been attributed to ancient river connections (Tan et al. 2012). This shared paleodrainage history further supports the hypothesis that O. flavicauda may also occur on Sumatra. A photograph tentatively identified as O. flavicauda from Sumatra has been pub‑ lished on iNaturalist (observation id 152813191; https://www.inaturalist.org/observations/152813191), although some contributors have alternatively identified it as O. waandersii, and there is currently no consensus on the identification of this specimen. Therefore, additional studies are required to confirm the accurate identifica‑ tion of this iNaturalist observation, as well as the occurrence of the species in Sumatra. Such records are critically important for conservation because freshwater fish distribution data under‑ pin occurrence maps, conservation status assessments, and regional checklists (Hasan et al. 2024). Docu‑ menting previously unsampled areas such as the Bangka and Belitung islands (Bangka‑Belitung Islands Province) helps fill major knowledge gaps and supports conservation decisions (Valen et al. 2024). The case of Mastacembelus notophthalmus Roberts, 1989—listed as Least Concern yet seldom recorded and poorly understood in population terms (Hasan et al. 2023b)—highlights the need for extensive sampling in un‑ derexplored areas, including smaller islands of the Bangka‑Belitung Islands Province and other parts of the Indonesian Archipelago. Similarly, the new records of O. flavicauda suggest that the species is more wide‑ spread but underdocumented, reinforcing the call for additional fieldwork, particularly on Sumatra’s main island, where the species may also occur. The shared paleodrainage history further supports the hypothesis that O. flavicauda may have a broader distribution than previously recognized. These findings fit within a broader biogeographic and conservation context. Sundaland is one of the world’s most threatened biodiversity hotspots, having experienced a rapid increase in threat levels over recent decades (Sholihah et al. 2020). Analyses indicate that up to 16 freshwater fish species in Sundaland may face extinction by 2050, primarily due to the conversion of natural habitats into agricultural areas (Giam et al. 2012). Considering that freshwater ecosystems are among the most imperiled globally, with nearly one‑quarter of freshwater fauna at risk of extinction (Sayer et al. 2025), conducting comprehensive sampling in understudied areas of Sundaland is both urgent and essential. Future efforts should prioritize expanding regional ichthyological surveys, strengthening taxonomic and molecular capacities for species identifica‑ tion, and integrating new occurrence data into conservation planning and habitat management. ACKNOWLEDGEMENTS We thank Dr. Tan Heok Hui (Lee Kong Chian Natural History Museum, Singapore) for confirming the iden‑ tification of the specimens. This study was partially supported by research fellowships from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil): CNPq productivity fellowships to FPO (307974/2021–9; 306490/2024–2); and CNPq DTI fellowship to RFO (382068/2025–4). We also thank the three reviewers and the academic editor for their valuable suggestions and corrections to the manuscript. ADDITIONAL INFORMATION Conflict of interest The authors declare that no competing interests exist. Ethical statement No ethical statement is reported. Funding This study was financially supported by Airlangga University IRN research grant 2024 and UKRI Future Lead‑ ers Fellowship [no: MR/X035662/1]. Author contributions Conceptualization: VH. Data curation: VH, ABA. Formal analysis: RFO, CTSF, VH, ABA, FPO. Funding acquisi‑ tion: VH. Investigation: VH, RFO, CTSF, ABA, FPO. Methodology: VH, RFO, FPO. Project administration: VH. Check List 21 (6) · https://doi.org/10.15560/21.6.1092 Hasan et al. · First records of Osteochilus flavicauda for Indonesia 1097 Data Validation: VH. Visualization: VH, RFO, CTSF, AFS, FSV, ASK, ABA, DS, FPO. Writing – original draft: VH, RFO, CTSF, FPO. Writing – review and editing: VH, RFO, CTSF, AFS, FSV, ASK, ABA, DS, JS, FPO. Author ORCID iDs Veryl Hasan https://orcid.org/0000‑0001‑5457‑9335 Rafael F. Oliveira https://orcid.org/0000‑0002‑1659‑2923 Carlos Thiago S. Filgueira https://orcid.org/0000‑0002‑7502‑4045 Ahmad F. Syarif https://orcid.org/0000‑0001‑6646‑7533 Fitri S. Valen https://orcid.org/0000‑0001‑8678‑3752 Ahmad S. Kamarudin https://orcid.org/0000‑0002‑5529‑2974 Amirudin B. Ahmad https://orcid.org/0000‑0002‑7775‑1289 Dian Samitra https://orcid.org/0000‑0003‑3459‑3660 Josie South https://orcid.org/0000‑0002‑6339‑4225 Felipe P. Ottoni https://orcid.org/0000‑0002‑9390‑0918 Data availability All data that support the findings of this study are available in the main text. REFERENCES Ahmad A, Fahmi-Ahmad M, Aqmal-Naser M, Rizal SA, Zakaria ZA, Lokman MIN, Rasul AHM, Intan Faraha AG, Khaironizam MZ, Amal MNA (2023) Fishes of Tasek Bera, Pahang. Ministry of Natural Resources, Environment and Climate Change, Malay‑ sia. pp. 154. Ahmad AB (2019) Osteochilus flavicauda. The IUCN Red List of Threatened Species 2019: e.T89848624A89848634. https://doi. org/10.2305/iucn.uk.2019‑2.rlts.t89848624a89848634.en Campos DS, Oliveira RFD, Vieira LO, Bragança PHN, Nunes JLS, Guimarães EC, Ottoni FP (2023) Revisiting the debate: doc‑ umenting biodiversity in the age of digital and artificially generated images. Web Ecology 23 (2): 135–144. https://doi. org/10.5194/we‑23‑135‑2023 Fricke R, Eschmeyer WN, Fong JD (2025a) Eschmeyer’s catalog of fishes: Species by family/subfamily. California Academy of Sci‑ ences. http://researcharchive.calacademy.org/research/ichthyology/catalog/SpeciesByFamily.asp. Accessed on: 2025‑17‑10. Fricke R, Eschmeyer WN, van der Laan R (eds) (2025b) Eschmeyer’s catalog of fishes: genera, species, references. California Acad‑ emy of Sciences. http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. Accessed on: 2025‑17‑ 10. Froese R, Pauly D (2025) FishBase. Version (04/2025). http://www.fishbase.org Accessed on: 2025‑17‑10. Giam X, Koh LP, Tan HH, Miettinen J, Tan HTW, Ng PKL (2012) Global extinctions of freshwater fishes follow peatland conversion in Sundaland. Frontiers in Ecology and the Environment 10: 465–470. https://doi.org/10.1890/110182 Hasan V, Ottoni FP, South J (2023a) First record of the vulnerable freshwater fish Lobocheilos falcifer (Valenciennes, 1842) (Teleostei: Cyprinidae) in Sumatra, Indonesia. Check List 19 (1): 51–55. https://doi.org/10.15560/19.1.51 Hasan V, Vieira LO, South J, Ottoni FP (2023b) First record of Mastacembelus notophthalmus Roberts, 1989 (Synbranchiformes: Mas‑ tacembelidae) for Belitung Island, Indonesia. Acta Ichthyologica et Piscatoria 53: 123–127. https://doi.org/10.3897/aiep.53.105318 Hasan V, South J, Valen FS, Andriyono S, Vieira LO, Sambah AB, Ottoni FP (2024) First record of Saddle Barb, Barbodes sellifer Kottelat & Lim, 2021 (Cypriniformes: Cyprinidae), on Belitung, Indonesia, with an update of its geographic distribution. Check List 20 (2): 524. https://doi.org/10.15560/20.2.524 Hutama AA, Hadiaty RK, Hubert N (2016) Biogeography of Indonesian freshwater fishes: current progress. Treubia 43: 17–30. https://doi.org/10.14203/treubia.v43i0.2969 Imron I, Anggraeni F, Pamungkas W, Marnis H, Himawan Y, Astuti DN, Palimirmo FS, Arifin OZ, Subagja J, Mokodongan DF, Hidayat R (2024) Intraspecific diversity and phylogeography of bony lip barb, Osteochilus vittatus, in Sundaland, as revealed by mitochondrial cytochrome oxidase I (mtCOI). Fisheries and Aquatic Sciences 27 (3): 145–158. https://doi.org/10.47853/FAS.2024. e15 Karnasuta J (1993) Systematic revision of southeastern Asiatic cyprinid fish genus Osteochilus with description of two new species and a new subspecies. Journal of Fisheries and Environment 19: 1–105. Kottelat M, Tan HH (2009) Osteochilus flavicauda, a new species of fish from the Malay Peninsula (Teleostei: Cyprinidae). Ichthyo‑ logical Exploration of Freshwaters 20 (1): 1–5. Nelson JS, Grande TC, Wilson MVH (2016) Fishes of the world. Fifth edition. Wiley, Hoboken, USA, 707 pp. https://doi. org/10.1002/9781119174844 Pubellier M, Morley CK (2014) The basins of Sundaland (SE Asia): evolution and boundary conditions. Marine and Petroleum Geol‑ ogy 58: 555–578. https://doi.org/10.1016/j.marpetgeo.2013.11.019 Sayer CA, Fernando E, Jimenez RR, Macfarlane NB, Rapacciuolo G, Böhm M, Darwall WR (2025) One‑quarter of freshwater fauna threatened with extinction. Nature 638 (8049): 138–145. https://doi.org/10.1038/s41586‑024‑08375‑z Sholihah A (2020). Diversification of Sundaland aquatic biotas: build‑up of freshwater fishes’ diversity and distribution in a biodi‑ versity hotspot. PhD Thesis, Université Montpellier, France. Sodhi NS, Brook BW (2006) Southeast Asian biodiversity in crisis. Cambridge University Press, Cambridge, UK, 210 pp. Tan MP, Jamsari AFJ, Siti Azizah MN (2012) Phylogeographic pattern of the striped snakehead, Channa striata, in Sundaland: ancient river connectivity, geographical and anthropogenic signatures. PLoS ONE 7 (12): e52089. https://doi.org/10.1371/journal. pone.0052089 Valen FS, Mamat NB, South J, Ottoni FP, Vieira LO, Kamarudin AS, Afandi AY, Hasan V (2024) Unveiling the occurrence of vulner‑ able sisorid catfish (Teleostei: Sisoridae) in Bangka based on morphological and molecular evidence. Biodiversitas Journal of Biological Diversity 25 (11): 4543–4550. https://doi.org/10.13057/biodiv/d251153 Check List 21 (6) · https://doi.org/10.15560/21.6.1092 Hasan et al. · First records of Osteochilus flavicauda for Indonesia 1098 Voris HK (2000) Maps of Pleistocene sea levels in Southeast Asia: shorelines, river systems and time durations. Journal of Bioge‑ ography 27 (5): 1153–1167. Yang L, Sado T, Hirt MV, Pasco-Viel E, Arunachalam M, Li J, Wang X, Freyhof J, Saitoh K, Simons AM, Miya M, He S, Mayden RL (2012) Phylogeny and polyploidy: resolving the classification of cyprinine fishes (Teleostei: Cypriniformes). Molecular Phyloge‑ netics and Evolution 65: 518–532. https://doi.org/10.1016/j.ympev.2015.01.014