hypomere

hypomere (noun; Greek hypo, under; meros, part): 1. (Arthropoda: Insecta) a. The ventral process of the phallobase. b. Inflexed edge of the pronotum and raised margin of the epipleura of beetles.

2. (Porifera) The basal portion of certain sponges in which no flagellated chambers develop.