Saurogobio punctatus sp. nov., a new cyprinid gudgeon (Teleostei: Cypriniformes) from the Yangtze River, based on both morphological and molecular data

Novel insights into adaptive evolution based on the unusual AT-skew in Acheilognathus gracilis mitogenome and phylogenetic relationships of bitterling

Acheilognathus gracilis, a bitterling species, distribute in lower reaches of Yangtze River. They are identified as the top-priority bitterling species for conservation as having high evolutionary distinctiveness and are at risk of extinction. In present study, we first sequenced the complete mitogenome of A. gracilis and analyzed its phylogenetic position using 13 PCGs. The A. gracilis mitogenome is 16,774 bp in length, including 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNAs, a control region and the origin of the light strand replication. The overall base composition of A. gracilis in descending order is T 27.9 %, A 27.7 %, C 26.1 % and G 18.3 %, shows a unusual AT-skew with slightly negative. Further investigation revealed A. gracilis uses excess T over A in NADH dehydrogenase 5 (nd5), whereas the most of other bitterlings are biased toward to use A not T, implying there is likely to be unique strategy of adaptive evolution in A. gracilis. We also compared 13 PCGs of 30 bitterling mitogenomes and the results exhibit highly conservative. Phylogenetic trees constructed by 13 PCGs strongly support the monophyly of Acheilognathus and the paraphyly of Rhodeus and Tanakia. Current results will provide valuable information for follow-up research on conservation of species facing with serious population decline and can provide novel insights into the phylogenetic analysis and evolutionary biology research.

Updated species checklist of fishes from Lake Dongting in Hunan Province, South China: Species diversity and conservation

A lack of an updated checklist of freshwater fish species from Lake Dongting is a great hindrance to further biodiversity analysis. A seasonal survey of fishes in the lake was conducted from October 2017 to January 2019. Based on the data obtained during the field survey and coupled with known literature and the latest taxonomic development of relevant taxa, the species checklist of fishes from Lake Dongting was updated. A total of 130 species from 12 orders, 30 families and 76 genera has been documented, containing 126 native species and four alien species. Its fish fauna is dominated by the Xenocyprididae that has the highest number of included species (30), followed by the Gobionidae (25) and Acheilognathidae (11). This checklist comprises 20 species undergoing nomenclatural changes and 11 new records, eight of which are native and three exotic. It excludes 20 species, which have been reported in error in historical works, due to synonyms, erroneous records, taxonomic changes and unconfirmed records. Unsampled in this survey were 34 species that are ecologically specialised: migratory, rheophilic, predatory, shellfish-dependent or pelagic-egg-spawning. While some of these species eluded capture likely due to the paucity of population, others may have been extirpated in Lake Dongting perhaps owing to human perturbations, such as river damming across affluents or the Chang-Jiang mainstem, sand dredging, overfishing or water pollution. The updated checklist lays a sound foundation for biodiversity conservation of fishes in Lake Dongting.

Four complete mitochondrial genomes of Saurogobio fishes (Cypriniformes: Gobionidae)

In this study, we determined complete mitochondrial genomes of Saurogobio gracilicaudatus, S. xiangjiangensis, S. gymnocheilus, and S. lissilabris so that these data could contribute to reconstruct interspecific phylogenetic relationships within the genus Saurogobio. The four mitochondrial genomes showed A + T bias (55.2-57.0%) of base compositions with the length from 16,594 to 16,608 bp. Phylogenetic relationships among Saurogobio fishes and their close relatives showed that the genus Saurogobio was a monophyletic group and it could be divided into two major groups.