An integrative approach to reappraising species validity in Pseudexostoma (Teleostei: Sisoridae)

The catfish genus Pseudexostoma (Sisoridae) currently contains three species: P. yunnanensis from the upper Irrawaddy River (Dayingjiang), and P. brachysoma and P. longipterus from the upper Salween River (Nujiang).

KUNFENG YANG1,2, WANSHENG JIANG1,5, XIAOYONG CHEN1,3, WEI ZHOU4 & JUNXING YANG1,5
1  State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
2  University of Chinese Academy of Sciences, Beijing 100049, China
3  Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Yezin, Nay Pyi Taw 05282, Myanmar
4  Key Laboratory of Forest Disaster Warning & Control in Yunnan Province, Faculty of Forestry, Southwest Forestry University, Kunming, Yunnan 650224, China
5  Corresponding authors. E-mail: jiangws@mail.kiz.ac.cn, yangjx@mail.kiz.ac.cn

PubYear : 2016
Volume : 4158 (3)
Publication Name : ZOOTAXA
Page number : 352–366

Abstract:
The catfish genus Pseudexostoma (Sisoridae) currently contains three species: P. yunnanensis from the upper Irrawaddy River (Dayingjiang), and P. brachysoma and P. longipterus from the upper Salween River (Nujiang). We adopted an integrative approach combining both morphology-based (traditional measurements, truss-based and geometric morphometrics, fin skeleton examination and X-ray photography) and molecular approaches (genetic distances, haplotype network, phylogenetic relationships) to reappraise species validity in Pseudexostoma. Our results showed that P. longipterus cannot be distinguished from P. brachysoma from either morphological or molecular analyses, and that the former name should thus be considered a junior synonym of the latter. The two remaining geographically isolated species, P. yunnanensis and P. brachysoma, showed a distinct genetic distance equated to the typical 2% sequence divergence threshold delineating different species of fishes, and with a divergence time dated to approximately 1.22–2.14 million years ago. Although P. yunnanensis and P. brachysoma share some morphological characters that appear gradually diverging (body depth at anus and interorbital distance), some degree of overlap still exists, we suggest the two species are distinct based on the total evidence.

Keywords: Glyptosternines, geometric morphometrics, X-ray, mitochondrial DNA, Yunnan

http://zoobank.org/urn:lsid:zoobank.org:pub:0702FD01-88ED-4AAC-8DBC-C07E45DC5780