Gastroxides ater is a species of horsefly found in India.

They complete only one life-cycle a year and the larvae grow very slowly and undergo a diapause in the dry season.

[1][2] Saunders created the genus Gastroxides on the basis of this species.

His type specimen came from "northern India" and was a female with completely black abdomen (ater referring in Latin to black) and a few years later he saw a male in the collections of Colonel Hearsey with a "rufous" band.

He described the genus as having three ocelli on the vertex of the head and also separated it from the genus Tabanus based on relative sizes of the three segments of the ringed antenna and the shape of the abdomen.