Neotype designation and redescription of Sinocyclocheilus cyphotergous (Dai) 1988, a rare and bizarre cavefish species distributed in China (Cypriniformes: Cyprinidae)

Abstract

Sinocyclocheilus cyphotergous was described by Dai in 1988 as Gibbibarbus cyphotergous based on a single specimen collected in Luodian County, Guizhou Province, China. The holotype (the only one type specimen) has been lost and the original description was vague and was published in a report with limited circulation. A specimen collected from the type locality in 2015 was the basis for a detailed redescription of the species and designation of a neotype. Sinocyclocheilus cyphotergous can be distinguished from all other congeners by the following combination of characters: a humpback profile with a fleshy dorsal projection; a hard last unbranched ray of dorsal fin with a serrated rear edge; and nearly straight lateral line. This species is the only member of the genus with a fleshy dorsal projection composed of adipose tissue (either a bony projection located on the nape or fleshy humpback is present in all other species). The conservation status of S. cyphotergous is uncertain and most likely critical due to its limited distribution, apparent rarity (based on low frequency of detection), and the potential for increased impacts to its habitat due to diminished quantity and quality of groundwater.