Oreonectes guilinensis (Teleostei, Cypriniformes, Nemacheilidae), a new loach species from Guangxi, China

A new loach Oreonectes guilinensis sp. nov. is described from Guangxi Zhuang Autonomous Region, China. It is the second surface-dwelling fish identified in the genus Oreonectes after the type species Oreonectes platycephalus. This new species can be distinguished from other species within the genus by the combination of the following features: a round caudal fin, 13-14 branched rays, an incomplete lateral line with 4-6 pores, a short pelvic fin located some distance from the anus, a scale-covered body, a stout build (body width 14.0%-16.7% of standard length), a posterior chamber of well-developed airbladder and a yellowish-brown body with a lateral dark brown strip. The maximum likelihood phylogenetic analysis based on cytb gene recovered this new species in a well-supported clade with the type species O. platycephalus, sister to the Lefua clade. Morphological comparisons as well as our phylogenetic tree support Oreonectes shuilongensis, Oreonectes daqikongensis, Oreonectes jiarongensis as species of Troglonectes. Based on our results there are 6 valid species in the genus Oreonectes.