Abstract
A new cyprinid gudgeon, Saurogobio rarus sp. nov., is described here based on morphological and molecular data. Morphologically, the new species resembles its congener S. dabryi the most, but with distinct differences. S. rarus sp. nov. has the naked area on chest restricted to or a little over the pectoral‐fin base, as opposed to extending much over the pectoral base or extending to posterior portion of the pectoral fin rays in S. dabryi . Besides, S. rarus sp. nov. has a relatively shorter snout, shorter and deeper caudal peduncle and a shorter distance between the anus and the pelvic‐fin base, compared with S. dabryi . The new species can be distinguished from other congeners by having eight branched dorsal‐fin rays, thick lips with numerous globular papillae and the absence of fin spots. Phylogenetically, based on cytb sequence analyses, S. rarus sp. nov. is clearly separated from all congeners, with a mean genetic distance from 0.022 to S. dabryi , exceeding the mean intraspecific distance of 0.012 observed within S. dabryi . At present, this new species has been found only in Central (Poyang Lake) and Northeastern China (Ussuri River and Songhua River). Based on our recent surveys, its abundance is becoming lower and lower, and calls for urgent conservation.