A key to known species of Microphysogobio in the Yangtze River Basin 1a. Lip papillae system undeveloped........................... Microphysogobio microstomus (middle and lower reaches) 1b. Lip papillae system developed.......................................................................... .. 2 2a. Width of cutting edge on upper jaw larger than half mouth width, midventral region scaleless before pelvic-fin insertion................................................................... Microphysogobio nudiventris (middle reaches) 2b. Width of cutting edge on upper jaw smaller than half mouth width.............................................. 3 3a. Midventral region scaleless before two-thirds of the distance from the pectoral-fin insertion to the pelvic-fin insertion............................................................ Microphysogobio kiatingensis (upper and middle reaches) 3b. Midventral scaleless region only before pectoral-fin insertion.................................................. 4 4a. Air-bladder length smaller than eye diameter............................................................... 5 4b. Air-bladder length equal to eye diameter, central anterior papillae equal or slightly larger than all other papillae on upper lip, vertebral counts 4+32................................................. Microphysogobio bicolor (middle reaches) 5a. Vertebal counts 4+30–31, lateral-line scales 35–37.......................... Microphysogobio zhangi (middle reaches) 5b. Vertebal counts 4+34, lateral-line scales 38–39............................................................................................. Microphysogobio tungtingensis (rivers of Lake Dongting System in the middle reaches)

Published as part of Sun, Zhixian & Zhao, Yahui, 2022, Revalidation and redescription of a gobionine species Microphysogobio bicolor (Nichols, 1930) (Teleostei: Cypriniformes) from the Yangtze River Basin, China, pp. 361-377 in Zootaxa 5092 (3) on pages 374-375, DOI: 10.11646/zootaxa.5092.3.7, http://zenodo.org/record/5881381