Two new species of shovel-jaw carp Onychostoma (Teleostei: Cyprinidae) from southern Vietnam

Abstract

Two new species of large shovel-jaw carps in the genus Onychostoma are described from the upper Krong No and middle Dong Nai drainages of the Langbiang Plateau in southern Vietnam. These new species are known from streams in montane mixed pine and evergreen forests between 140 and 1112 m. Their populations are isolated in the headwaters of the upper Sre Pok River of the Mekong basin and in the middle of the Dong Nai basin. Both species are differentiated from their congeners by a combination of the following characters: transverse mouth opening width greater than head width, 14−17 predorsal scales, caudal-peduncle length 3.9−4.2 times in SL, no barbels in adults and juveniles, a strong serrated last simple ray of the dorsal fin, and small eye diameter (20.3−21.5% HL). Onychostoma krongnoensis sp. nov. is differentiated from Onychostoma dongnaiensis sp. nov. by body depth (4.0 vs. 3.2 times in SL), predorsal scale number (14−17 vs. 14−15), dorsal-fin length (4.5 vs. 4.2 times in SL), caudal-peduncle length (3.9 vs. 4.2 times in SL), colour in life (dark vs. bright), and by mitochondrial DNA (0.2% sequence divergence). Molecular evidence indicates that both species are members of Onychostoma and are distinct from all congeners sampled (uncorrected sequence divergences at the 16S rRNA gene of >2.0% for all Onychostoma for which homologous 16S rRNA sequences are available).

Complete mitochondrial genome of the freshwater fish Onychostoma lepturum (Teleostei, Cyprinidae): genome characterization and phylogenetic analysis

“…The present study strongly supported that some species of Acrossocheilus, Onychostoma and F. brevifilis belong to the monophyletic group (Clade III), including A. monticola, A. yunnanensis, O. rarum, O. alticorpus and F. brevifilis. Interestingly, our results corroborate the previous finding that O. rarum is the sister group of O. alticorpus (Hoang et al 2015;Song et al 2018;Zhang et al 2018), but Zhai et al (2020) suggested that O. rarum appeared to be more closely related with O. barbatulum and O. barbatum. We suggested that the specimens of O. rarum (NC022869.1) were also misidentified.…”

Langbiangia, a new genus of Gesneriaceae endemic to Langbiang Plateau, southern Vietnam and a taxonomic endeavor to achieve key targets of the post-2020 global biodiversity framework

“…Additionally, a rich diversity in bats has also been documented in the region [15]. In the recent decade, several new vertebrates including six fishes [16,17], three snakes [18][19][20], and four amphibians [21][22][23][24] were described from the Langbiang Plateau. Across the plateau, cryptic genetic diversity was also detected in the frog genus Leptolalax [25].…”