Stenopodidea is comprised of the family Spongicolidae, which includes five genera (Spongicoloides, Spongiocaris, Spongicola, Paraspongicola, and Microprosthema), and the family Stenopodidae, with four genera (Engystenopus, Odontozona, Richardina, and Stenopus). In Brazil, Stenopodidea is represented by two species of the genus Stenopus and one of Microprosthema. For the present report, five larvae of two Spongicolidae collected during the cruise of the RV Thalassa between Rio Real (BA) and Cabo de São Tomé (RJ) were identified and described. Two species of Microprosthema were identified, one ascribed to M. semilaeve, the only member of Spongicolidae recorded until now in Brazil; and the other to an undescribed species of Microprosthema. The two species can be distinguished by the rostrum, which is as long as the carapace in M. semilaeve and shorter in Microprosthema sp.2; and by the presence of pleural spines on abdominal somites 1 to 3 in M. semilaeve and only on somites 2 and 3 in the second morphotype.
