Periophthalmus variabilis (Teleostei: Gobiidae: Oxudercinae), a valid species of mudskipper, and a re-diagnosis of Periophthalmus novemradiatus.

The current concept of Periophthalmus novemradiatus (Hamilton, 1822) includes two species. Procurement of fresh material and examination of extant type specimens revealed that P. novemradiatus differs from P. variabilis Eggert, 1935, primarily in the number of anal fin rays (I, 12 or 13 vs. I, 10-12); the lateral scale series (62-67 vs. 48-60); the extent of fusion of the pelvic fins (56.0-90.0% vs. 32.0-48.8%); and the patterns of the first and second dorsal fins.