We investigated collections of the alpheid shrimp Stenalpheops Miya, 1997, symbiotic in the burrows of gebiidean and axiidean shrimps, in Tokyo Bay, Japan to clarify ontogenetic changes in the diagnostic morphology of the cheliped and uropod. The uropod flaps were found only among the largest male shrimp, none among females. The number of articles of the uropod flap ranged from one to five, and uropod length was positively correlated with the length of the carapace. Furthermore, no chelae showing a subcheliped shape were found, while the angle of the propodus-pollex decreased with the development of the carapace. Ontogenetic changes in these characters support the view that the male cheliped is normal in S. anacanthus Miya, 1997 (subcheliped in S. crangonus Anker, Jeng & Chan, 2001), and the uropod flap is found only in the large males of S. anacanthus (in both males and females in S. crangonus).