‘Henicorhynchus’ thaitui sp. nov. is described from a subterranean stream in a karst cave in Phong Nha Ke Bang National Park, Quang Binh Province, Central Vietnam. It differs from all congeners in having a pale pink body in life, smaller eyes with diameter less than the maxillary barbel length, and two pairs of barbels, the maxillary barbel being much longer than the rostral barbel.

Molecular data from 35 of the 50 Acrossocheilinae species suggest that the species‐level diversity in the subfamily has been overestimated, likely due to inadequate taxon and geographic sampling and reliance on morphological characters that vary intraspecifically. Three new genera, one resurrected genus, two resurrected species, and one new species are diagnosed and described herein. Nine synonyms of three valid species of Acrossocheilinae are recognized from the Yangtze, Xijiang, Song Hong, Annamite, and Mekong ecoregions in East and Southeast Asia. Thirty‐two valid and six putative new species are indicated by molecular data and a key to the genera is provided. As more molecular and morphological data become available, additional taxonomic changes in this widespread and generally poorly known subfamily are likely.

The northern margin of the East Asian tropics harbors exceptional endemism, yet its freshwater fish fauna remains poorly characterized. Tachysurus virgatus, long considered a single widespread species in this region, exemplifies this taxonomic gap. Through integrative taxonomic analyses combining morphological and molecular evidence, we uncovered remarkable cryptic diversity within this species. Phylogenetic reconstructions reveal that true T. virgatus is restricted to the Wanquan River basin on Hainan Island, whereas nine additional lineages from other drainages represent previously unrecognized species described in this study. Together with two known congeners (T. spilotus and T. kyphus), these form the monophyletic T. virgatus species group for which we provide morphological diagnoses. Pronounced incongruence between morphological and molecular divergence characterizes this group, underscoring the necessity of integrative approaches for species delimitation in morphologically conserved lineages. Moreover, distinct habitat specialization patterns were identified within the group, with species exhibiting adaptations to three ecological niches: mainstem river, montane streams, and generalist habitats occupying both. Correlations between habitat preferences and functional morphology were preliminarily discussed. Using our revised taxonomic framework, we evaluated the conservation status of all species under IUCN Red List criteria, with several newly described taxa warranting threatened status due to extremely limited distributions. This study highlights the pervasive cryptic diversity of freshwater fishes in the north margin of East Asian tropics and emphasizes the critical importance of rigorous taxonomic resolution to guide effective conservation in this biogeographically complex region.

Parthenogenetic reptiles provide unique models for studying the ecological consequences of hybrid origin between related sexual species in zones of secondary overlap. Such clonal lineages inherit genetic material from both parental species, but little is known about how the combination of two distinct genomes affects ecological preferences in parthenogenetic species. In this study, we provide the first quantitative comparison of the realized climatic niche of the triploid parthenogenetic butterfly lizard Leiolepis guentherpetersi Darevsky et Kupriyanova, 1993 with the niches of its inferred sexual parental species, Leiolepis guttata Cuvier, 1829 and Leiolepis reevesii (Gray, 1831). These species are associated with coastal sandy habitats in Vietnam and occur in sympatry or in zones of secondary contact in the central part of the country. Species occurrence records were compiled from the literature, museum collections, open-access databases, and our own field surveys. Climatic niches were analyzed using bioclimatic variables, PCA-env ordination, niche-overlap and niche-dynamics metrics, Mahalanobis-based estimates of niche position and dispersion, and covariance-based niche-volume estimates. We found that L. guentherpetersi occupied the narrowest and most homogeneous realized climatic niche among the three species. Its niche was predominantly nested within the parental climatic space, with little to no expansion beyond it and substantial unfilling of the parental niche space. The parthenogenetic species showed greater climatic similarity to L. guttata than to L. reevesii, consistent with its asymmetric hybrid origin and a larger genomic contribution from L. guttata. Niche differentiation was expressed primarily along hydroclimatic gradients, and L. guentherpetersi was associated with higher precipitation in the wettest month, greater precipitation seasonality, higher precipitation during the coldest quarter, and lower precipitation during the warmest quarter. Within the framework of geographic parthenogenesis, this pattern is most consistent with the frozen niche variation hypothesis, suggesting that L. guentherpetersi occupies a narrow and hydroclimatically distinct part of the parental climatic space. Together, these findings identify L. guentherpetersi as a specialized hybrid parthenogenetic lineage and highlight Leiolepis as an informative system for studying how asymmetric ancestry, sympatry with sexual parental species, and climatic specialization contribute to ecological differentiation in unisexual vertebrates.

The study was conducted to provide data on species composition, diversity indexes, and community structure of plankton, contributing to the scientific foundation for biodiversity conservation efforts in the Dong Chau - Khe Nuoc Trong Nature Reserve. Samples were collected during two survey periods: the rainy season (November 2024) and the dry season (June 2025) at 10 representative water bodies. The study recorded 72 taxa of phytoplankton, belonging to 34 genera, 24 families, 19 orders, 4 classes, and 4 phyla. The phylum Heterokontophyta was dominant, accounting for 43% of the taxa. The number of taxa ranged from 64 species (first survey) to 70 species (second survey). The density ranged from 5,627 to 86,625 cells/l, with an average of 19,181 cells/l. The Shannon-Wiener diversity index (H’) ranged from 1.55 to 2.20, averaging 1.83, indicating a relatively low level of diversity. As for zooplankton, the study recorded 28 species and species groups, belonging to 9 orders, 20 families, and 19 genera. The Copepoda group accounted for the highest proportion of species (39%), with slight increase in the number of species and groups between the two survey periods. The density ranged from 240 to 580 individuals/m3, averaging 407 individuals/m3. The H’ index ranged from 1.87 to 2.49, with an average of 2.26, indicating a moderate level of diversity.