Key to the two body types of Athesmia Looss, 1899

1a. Both ceca extending to level of posterior margin of vitelline field, usually surpassing it posteriorly............................................................................... Athesmia attilae Travassos, 1917 body type (Figs. 4–5)

1b. Cecum on side of vitelline field terminating anterior to posterior margin of vitelline field, usually near anterior margin of vitelline field; cecum opposite to vitelline field extending to level of posterior margin of vitelline field, usually surpassing it posteriorly................................................ Athesmia heterolechithodes (Braun, 1899) body type (Fig. 6)