Sunday, July 10, 2016

[Ichthyology • 2016] Oreonectes shuilongensis • A New Species of the Genus Oreonectes (Cypriniformes: Nemacheilidae) from Guizhou, China


Oreonectes shuilongensis  
Deng, Xiao, Hou & Zhou, 2016
  DOI: 
10.11646/zootaxa.4132.1.13 

Abstract

This study examined the morphological and phylogenetic characteristics of Oreonectes shuilongensis sp. nov. The genus Oreonectes is distributed only in southwestern China and northern Vietnam.  Sixteen specimens of cavefish were captured in the Shuilong Township in Guizhou Province of China and identified as a new species of Oreonectes (Cypriniformes: Nemacheilidae).  Maximum likelihood was used to construct phylogenetic trees based on data for Nemacheilidae species accessible on GenBank. Molecular phylogenetic analyses showed that O. shuilongensis is closely related to O. platycephalus from which it is distinguished by having 6 vs. 5 branched anal rays, ratio of body length to body height 7.0–7.9 vs. 5.6–7.0, ratio of head length to distance between eyes 3.5–4.9 vs. 2.0–2.4, naked vs. scaly body, densely distributed fine black stains except on abdomen, and semitransparent body. Oreonectes shuilongensis is the only species of the genus not distributed in Guangxi Province. This study has contributed to the overall knowledge about the distribution of Oreonectes.

Keywords: Pisces, Nemacheilidae, Oreonectes, new species, cave fishes, Guizhou


Habitat. The species inhabits an underground river flowing in a cave. The cave, which opens near a hilltop, is approximately 150–200 m in length. The underground river is near the bottom of the cave and is approximately 15m long and 0.15–0.85 m wide. Its flow is gentle and clear, and the average depth of the water is 0.40 m. This new species was observed at depths of 0.01–0.40 m. In the underground river, the only other aquatic organisms found were small shrimps.

 Etymology. The specific epithet is based on the Chinese name “Shuilong,” which is the name of the township where the specimens were collected.


Discussion: 
Sequences for cytb were analyzed for several genera and species of nemacheilids using Mage 5.05 to elucidate relationships. The result showed Oreonectes to be genetically distant from all other genera (Fig. 4). The genetic distance between O. shuilongensis and O. platycephalus was 0.789, and the difference in the cytb sequences between O. shuilongensis and O. platycephalus was 15%, which was much higher than the genetic distance between several species (0.02–0.16) of Schistura. The results are consistent with the morphological data supporting O. shuilongensis as a separate species.
The genus Oreonectes is distributed in subterranean rivers in the karst land of the southwestern region of China. Oreonectes platycephalus is distributed across a wide area, mainly in Hong Kong, Guangdong, which belongs to the Pearl River system; and Guangxi, northern Vietnam, which belongs to the Red River system. The other 15 species are all distributed in the karst areas of Guangxi. O. shuilongensisis is distributed only in Guizhou Province and is the first species of the genus Oreonectes not distributed in Guangxi. The present findings contribute to the overall knowledge about the distribution of Oreonectes.


H. Deng, N. Xiao, X. Hou and J. Zhou. 2016. A New Species of the Genus Oreonectes (Cypriniformes: Nemacheilidae) from Guizhou, China. Zootaxa. 4132(1); 143–150.  DOI: 10.11646/zootaxa.4132.1.13

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