Austrostelis are slender and black bees that range in body length from 5.5–8.5 mm. They can have integument with variable amounts of pale yellow to orange maculations on the head, thorax, and abdomen, or can be almost entirely yellow (Michener 2007). Austrostelis are cleptoparasites, so they lack scopa (Michener 2007).
(modified from Michener 2007)
Austrostelis may be confused with Hypanthidioides because they are superficially similar in color and body conformation. However, females Hypanthidioides lack the characteristic projection of the hind tibia of Austrostelis and have scopae (Michener 2007). Hoplostelis is also similar; however, females also lack the flat projection on the hind tibia (Michener 2007).
There are no known invasives.
Austrostelis are cleptoparasitic, hence they do not gather pollen. Presumably, they utilize a wide variety of floral nectar resources. The host range of Austrostelis is largely unknown; however, they have been found in the nests of other Anthidiini (Michener 2007). Austrostelis catamarcencis has been recorded from Epanthidium tigrinum as a host in Brazil; A. iheringi has been reared from an unidentified anthidiine nest (Zanella and Ferreira 2005).
Austrostelis iheringi has been observed parasitizing host species in bamboo stalks (Cordeiro et al. 2015). The host female built a continuous, linear nest out of resin within the bamboo cane. Austrostelis iheringi occupied the entire nest with its diagonally constructed cocoon and feces (Cordeiro et al. 2015).
Austrostelis is a New World genus ranging from Mexico south to Colombia, Brazil, and Argentina (Michener 2007).