Species diversity of freshwater shrimp in Henan Province, China, based on morphological characters and COI mitochondrial gene.

Freshwater shrimp are a rich species group, with a long and problematic taxonomic history attributed to their wide distribution and similar morphological characteristics. Shrimp diversity and species identification are important cornerstones for fisheries management. However, identification based on morphological characteristics is a difficult task for a nonspecialist. Abundant freshwater shrimp species are distributed in the waters of Henan Province, but investigations of freshwater shrimp are limited in this region, especially concerning molecular features. Here, we combined morphology and DNA barcodes to reveal the species diversity of freshwater shrimp in Henan province. A total of 1,200 freshwater shrimp samples were collected from 46 sampling sites, and 222 samples were chosen for further microscopic examination and molecular delimitation. We used tree-based methods (NJ, ML, and bPTP) and distance-based methods (estimation of the paired genetic distances and ABGD) to delimit species. The results showed that there were nine morphospecies based on morphological characteristics; all could effectively be defined by molecular methods, among which bPTP and ABGD defined 13 and 8 MOTUs, respectively. The estimation of the paired genetic distances of K2P and the p-distances had similar results. Mean K2P distances and p-distances within species were both equal to 1.2%. The maximum intraspecific genetic distances of all species were less than 2%, with the exception of Palaemon modestus and M. maculatum. Various analyses have shown that P. modestus and M. maculatum have a large genetic differentiation, which may indicate the existence of cryptic species. By contrast, DNA barcoding could unambiguously discriminate 13 species and detect cryptic diversity. Our results demonstrate the high efficiency of DNA barcoding to delimit freshwater shrimp diversity and detect the presence of cryptic species.

A new species of Triplophysa (Cypriniformes, Nemacheilidae) from Weihe River in Gansu Province, China.

A new species of Tibetan loach, Triplophysa weiheensis sp. nov., is described from the Weihe River in Gansu Province, China, based on morphological and molecular analyses. The new species can be distinguished from all known congeners by a unique combination of the following characters: scaleless; snout abruptly sloping downward, anterior to anterior nostril; lower jaw crescentic, not sharp; body without obvious mottling; lateral line interrupted on posterior trunk at pelvic-fin distal extremity; caudal-peduncle length 2.0-2.7 times its depth; branched rays of pectoral fin 10-11; branched rays of pelvic fin 5-6; inner gill rakers on 1 st gill arch 14-16; vertebrae 4+34-36; intestine with 6-7 loops, length ca. 1.8 times SL ( n=3); bony capsule of air bladder small and thin; posterior chamber of air bladder absent.

Taxonomic status of a population of Gymoncypris waddelli Regan, 1905 (Cypriniformes: Schizothoracinae) distributed in Pengqu River, Tibet, China.

Gymnocypris waddelli, a highland cold-water fish, is distributed among rivers and lakes of the southern Qinghai-Tibet Plateau. Although previously described as G. waddelli, specimens from the Pengqu River are morphologically distinguishable from those from Lake Yamzhog Yumco, which is the type locality of G. waddelli. We investigated morphological variations of G. waddelli specimens from Pengqu River and Lake Yamzhog Yumco using not only traditional morphological methods but also newly-developed geometric morphometric analysis; furthermore, mitochondrial Cytochrome b (Cyt b) gene analysis was employed to explore the phylogenetic position of the Pengqu River population. Our morphological analyses suggested that G. waddelli from the Pengqu River had an obtuse snout, nearly straight oral fissure, shorter lower jaw than upper jaw, broad mouth and sparse inside gill rakers of the first arch relative to the Lake Yamzhog Yumco population. The strongly supported monophyly of Pengqu population according to mitochondrial datasets was obtained, indicating genetic differences between Pengqu River and Lake Yamzhog Yumco populations. Given their substantial genetic and morphological divergence, specimens from Pengqu River warrant recognition as a distinct species, here described and named Gymnocypris pengquensis.

[Morphological differentiations of the gills of two Gymnocypris przewa-lskii subspecies in different habitats and their functional adaptations].

Gill morphologies of two subspecies of Gymnocypris przewalskii (Gymnocypris przewalskii przewalskii and Gymnocypris przewalskii ganzihonensis) in different habitats were analyzed under scanning electron microscope. Results indicated that G. p. przewalskii had numerous long and dense-lined gill rakers while G. p. ganzihonensis had few short and scatter-lined gill rakers. There were no significant differences in distance between gill filaments (DBF) and distance gill lamella (DBL) between the two subspecies, but gill filaments of G. p. przewalskii were longer than in G. p. ganzihonensis. The electron microscopic study indicated that the pavement epithelium cells of G. p. przewalskii were well defined as irregular ovals, but were hexagonal in G. p. ganzihonensis. Moreover, G. p. przewalskii had more chloride cells than G. p. ganzihonensis, and mucous cells were only found on the surface of gill filaments of G. p. przewalskii. The morphological differences between the two subspecies of G. przewalskii are adaptations to their corresponding diets and habitats.