Revision of Schizopygopsis chengi Fang 1936 (Cypriniformes: Cyprinidae), with a description of a new subspecies

The species status of Schizopygopsis chengi, which is defined as a subspecies of Schizopygopsis malacanthus, is under debate. In the present study, comprehensive morphological and molecular analyses were performed on S. chengi, its closest relatives S. malacanthus and other Schizopygopsis fishes. The results showed that S. chengi did not form a sister lineage to S. malacanthus, with morphological differences in unbranched rays of the dorsal fin. The morphological and molecular evidence indicated that S. chengi was a valid species and was separated from S. malacanthus. By examining specimens of S. chengi from the Marke River, Keke River, Duoke River and Baoxing River, populations from the Duoke River showed morphological characteristics of mouth inferior, transverse oral fissure, relative long predorsal length than other geographic populations. The monophyly of population from Duoke River was strongly supported by mitochondrial sequence datasets. Based on morphological and molecular evidence, specimen from Duoke River is considered a newly identified subspecies and named as Schizopygopsis chengi duokeheensis.