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

Oreonectes yuedongensis (Cypriniformes, Nemacheilidae), a new freshwater fish species from the Lianhua Mountains in eastern Guangdong, China

In this work, we describe a new species of the genus Oreonectes, Oreonectes yuedongensis sp. nov., collected from the Lianhua Mountains in eastern Guangdong, China. Phylogenetic trees constructed based on the mitochondrial cytochrome b (Cyt b) gene showed that this new species represents an independent evolutionary lineage, with uncorrected genetic distances (Kimura 2-parameter model) from congeners ranging from 5.1% to 8.3%. In addition, nuclear DNA analysis indicated O. yuedongensis as an independent lineage separate from its closely related species. Morphologically, the new species can be distinguished from other six species in the genus Oreonectes by a combination of serial characters. The description of this new species suggests that it is necessary to reassess the biodiversity of Oreonectes platycephalus as a complex, especially in the middle reaches of the Pearl River near the border between Guangdong and Guangxi. Morphological and genetic evidence supports O. yenlingi as a synonym of O. platycephalus.

A new loach species of the genus Oreonectes (Teleostei, Cypriniformes, Nemacheilidae) from Guangxi, China

A new loach species, Oreonectesandongensissp. nov. is described from the Guangxi Zhuang Autonomous Region, China. The new species can be differentiated from other members of the genus by combinations of characters: a developed posterior chamber of the swim bladder, 13-14 branched caudal-fin rays, 8-16 lateral-line pores, body width 12-15% of standard length (SL), interorbital width 42-47% of head length (HL), and caudal peduncle length 11-16% of SL. Bayesian inference phylogenetic analysis based on mitochondrial Cyt b provided strong support for validity of O.andongensissp. nov. (uncorrected p-distance 6.0-7.5%).

A long-ignored unique ecosystem of cavefishes in the southern karst: achievements, challenges, and prospects

Cavefishes represent a taxon that has experienced natural selection pressures. This paper summarizes the results with respect to the taxonomy, diversity, phylogeny, and adaptation aspects of cavefishes research. It showed that: 1) These studies suggest that cavefishes play important roles in the study of geologic history and adaptation to extreme environments, but the mechanisms involved 168 species of cavefishes belonging to 17 genera, four families, and two orders have been recorded in China. Meanwhile, more new species are being discovered recently, and the species diversity of cavefishes are still underestimated, indicating the need to strengthen the survey in field. 2) The biogeography of cavefishes have focused on Sinocyclocheilus and Triplophysa, that have helped understand the geomorphology of karst areas in southern China and the spatial pattern of species diversity. These studies revealed the influences of evolution and geological history in Sinocyclocheilus, but there are still many species that have not been studied accordingly. 3) Some adaptive mechanistic studies have been conducted on cavefishes, primarily focusing on eye and body color degradation and energy metabolism in the genus Sinocyclocheilus to reveal adaptive mechanisms in the dark environment. 4) The IUCN list of protected cavefishes species in China only includes 21 species. The List of Key Protected Wild Animals for 2021 includes all species of Sinocyclocheilus as National Class II.It is necessary to strengthen the research on the biodiversity and adaptation and need consider the conservation actions for cavefishes.

Complete mitochondrial genome of Eonemachilus longidorsalis (Cypriniformes: Nemacheilidae): genome characterization and phylogenetic consideration

For the first time, this study presents the complete mitochondrial genome and phylogenetic analysis of Eonemachilus longidorsalis, an endemic species in southwest China. The mitogenome is a circular molecule of 16,569 bp in length with a base composition of 30.2% A, 27.3% T, 16.6% G, and 25.9% C. The phylogenetic analysis based on the complete mitogenomes shows that E. Longidorsalis clusters with Yunnanilus jiuchiensis, Yunnanilus pleurotaenia and Eonemachilus niger. This contribution may provide a valuable framework for completely resolving phylogenetic relationships of the family Nemacheilidae in future research.

Troglonectes canlinensis sp. nov. (Teleostei: Nemacheilidae), a New Troglomorphic Loach from Guangxi, China

A new species of the genus Troglonectes is described based on specimens from a karst cave in Andong Town, Xincheng County, Liuzhou City, Guangxi, China. Troglonectes canlinensis sp. nov. can be distinguished from its congener species by the following combination of characteristics: eye degenerated into a black spot; whole body covered by scales, except for the head, throat, and abdomen; incomplete lateral line; forked caudal fin; 8-10 gill rakers on the first gill arch; 13-14 branched caudal fin rays; 8-9 branched dorsal fin rays; 5-6 anal fin rays; 9-10 pectoral fin rays; upper adipose keel depth mostly 1/2 of the caudal peduncle depth; and caudal fin forked.

Diversity, Distribution, and Biogeography of Freshwater Fishes in Guangxi, China

Simple Summary

The Guangxi Zhuang Autonomous Region has one of the most abundant aquatic biodiversity in China, and it is a hotspot of global biodiversity research. In the present study, we explored the diversity, distribution, and biogeography of freshwater fishes in Guangxi. Our results showed that 380 species of freshwater fishes were recorded in Guangxi; the species diversity from northwest to southeast gradually decreased for most Sub−basins; the spatial turnover component was the main contributor to beta diversity; the freshwater fish system belonged to the South China division in the Southeast Asiatic subregion of the Oriental region.

Abstract

The Guangxi Zhuang Autonomous Region has the largest number of cavefish species in the world and is a global biodiversity hotspot. In this study, a species list of freshwater fishes in 12 Sub−basins of Guangxi was compiled systematically. Moreover, the species composition and distribution of the diversity were analyzed via the G-F index, taxonomic diversity index, and beta diversity index. Results showed that 380 species of freshwater fishes were recorded in this region, which belonged to 158 genera in 43 families and 17 orders in 2 phyla, in which 128 species of endemic fishes and 83 species of cavefish accounted for 33.68% and 21.84%, respectively. The species diversity from northwest to southeast gradually decreased for most Sub−basins. The G-F index has generally risen in recent years. The taxonomic diversity index showed that the freshwater fish taxonomic composition in Guangxi is uneven. The spatial turnover component was the main contributor to beta diversity. A cluster analysis showed that the 12 Sub−basins in the study area could be divided into four groups, and the phylogenetic relationships of freshwater fishes in Guangxi generally reflect the connections between water systems and geological history. The freshwater fish system in Guangxi, which belonged to the South China division in the Southeast Asiatic subregion of the Oriental region, originated in the early Tertiary period. The results will provide the information needed for freshwater fish resource protection in Guangxi and a reference for promoting the normalization of fish diversity conservation in the Pearl River Basin and other basins.

Eight in One: Hidden Diversity of the Bagrid Catfish Tachysurus albomarginatus s.l. (Rendhal, 1928) Widespread in Lowlands of South China

There is increasing evidence that species diversity is underestimated in the current taxonomy of widespread freshwater fishes. The bagrid species T. albomarginatus s.l. is mainly distributed in the lowlands of South China, as currently identified. A total of 40 localities (including the type locality), which covers most of its known range, were sampled. Molecular phylogenetic analyses based on concatenated mtDNA and nuclear genes recover nine highly supported lineages clustering into eight geographic populations. The integration of molecular evidence, morphological data, and geographic distribution demonstrates the delineation of T. albomarginatus s.l. as eight putative species. Four species, namely, T. albomarginatus, T. lani, T. analis, and T. zhangfei sp. nov. and the T. similis complex are taxonomically recognized herein. Moreover, T. zhangfei sp. nov. comprises two genetically distinct lineages with no morphological and geographical difference. This study also reveals aspects of estimation of divergence time, distribution, and ecological adaption within the T. albomarginatus group. The unraveling of the hidden species diversity of this lowland bagrid fish highlights the need for not only the molecular scrutiny of widely distributed species of South China but also the adjustment of current biodiversity conservation strategies to protect the largely overlooked diversity of fishes from low-elevation rapids.

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 hechiensissp. 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.