Bialba rotunda is a species of fly belonging to the family Drosophilidae.

The species, which is the sole member of the genus Bialba, was originally described from a specimen obtained in Queensland, Australia.

Tozer in the Iron Range on a collecting expedition conducted by the CSIRO Division of Entomology in the summer of 1986 and was described, along with its genus, by Ian R. Bock in 1989.

[2][1] Bialba sport feathery arista with lateral white bands and orbital bristles on the posterior half of the front, as well as a single vibrissa.

The scutellum is bulbous and a similar color to the mesonotum, with two pairs of macrochaetae but no setae.