The name describes differentiation of its pereiopods (thoracic appendages) as possible adaptation to commensal life-style.

Compared to other genera of the subfamily Heteromysinae, Heteromysis is most similar to Ischiomysis, Platymysis and Retromysis.

From Platymysis it is distinguished by the general body shape, which is not compressed dorsoventrally, laking also the abdominal pleurites, the prominent distolateral lobes on the eyes and the pereiopod 1 carpopropodus segments clearly separate.

Finally, Heteromysis differs from Retromysis by the distomedial setae of the antennal peduncle, directed forward instead of backwards, the absence of the posteromedial lobe on the male process of antennula and the sternal plate not projecting behind the marsupium.

Some species were recorded to be facultative commensals, also inhabiting adjacent bottom substrates.

The ischium of the pereopod 1 endopod is two to three times as long as wide; medially not bearing denticles.

The ischium of the pereopod 1 endopod is nearly as long as wide, triangular, with characteristic medial denticles.

The carpopropodus of the pereopod 1 is exceptionally large, longer than or as long as the merus, bearing strong medial spine-like setae.

Its only species has unique serrations of the pereopod 1 dactylus and exceptionally long flagellated setae on the male pleopods.

Heteromysis fosteri was named after South African filmmaker Craig Foster, after he had discovered eight new species of shrimp during a year of diving every single day while filming a common octopus.