Wednesday, December 13, 2017

[Ichthyology • 2017] Exostoma gaoligongense • A New Species of Sisorid Catfish of the Genus Exostoma from the Salween drainage, Yunnan, China

 Exostoma gaoligongense
Chen, Poly, Catania & Jiang, 2017

A new species of the sisorid catfish genus Exostoma Blyth, 1860 was collected from two hill-stream tributaries of the Nujiang (Salween River) drainage in Gaoligong Mountain, south-western Yunnan Province, China from 2003 to 2006 and from two tributaries of the Salween River in Cangyuan County, Lingcang Prefecture, Yunnan Province, China (in 2007) and in Yongde County, Lingcang Prefecture, Yunnan Province, China (in 2015). Exostoma gaoligongense sp. nov. is the 10th species of the genus and is most similar to E. vinciguerrae in morphology but can be distinguished by pelvic fin reaching anus vs. not reaching; maxillary barbels just reaching or slightly surpassing pectoral-fin origin vs. surpassing pectoral-fin origin or even reaching posterior end of gill membrane; abdominal vertebrae 23-25 vs. 25-27; length of dorsal fin/dorsal to adipose distance 90.3%-287.0% vs. 59.2-85.7. A key to Exostoma spp. is provided.

Keywords: Glyptosterninae; Sisoridae; Nujiang; Gaoligong Mountain; Yunnan

Figure 1: Holotype of Exostoma gaoligongense sp. nov. (KIZ 200310738); lateral (top), dorsal (middle), and ventral (bottom) views (photos by Xiao-Yong Chen)

Exostoma gaoligongense sp. nov.

Etymology: The specific name is an adjective that refers to the Gaoligong Mountain in which the type locality is located, and the suffix agrees in gender with the generic name Exostoma (gender neuter).

Notes on biology: This species was collected from shallow water ( < 1 m deep) in a fast flowing stream with clear water. Water temperature was 18.8 ℃, water pH 6.95, conductivity 45.6 μS/cm. The bottom substrate was boulders, cobbles, gravel, and sand with many diatoms that made the rocks slippery. This species was obtained from fast water and small waterfalls. The new species of Exostoma seems to have much lower tolerance to either low dissolved oxygen or to stress from electrofishing than Pseudexostoma brachysoma Chu, 1979, which occurs in the same habitat. After shocking sampling on 7 October 2003, all the Exostoma were dead, whereas all the individuals of P. brachysoma survived until the next morning.

Xiao-Yong Chen, William J. Poly, David Catania and Wan-Sheng Jiang. 2017. A New Species of Sisorid Catfish of the Genus Exostoma from the Salween drainage, Yunnan, China. Zoological Research. 38(5);  291-299.
A Chinese biologist’s 14-year quest to prove his new catfish species via @SCMP_News

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