A new species of Monstrilla (Crustacea : Copepoda : Monstrilloida) from Brazil with notes on M-brevicornis Isaac

Monstrilla pustulata n.sp., is described from three adult females collected in the Guanabara Bay system on the coast of Brazil. The new species is sim ilar to M. brevicornis Isaac in having a peculiar, conical, horn-like protu berance on the ventral surface near the antennular bases. The new species i s compared with the holotype of M. brevicornis, from the Java Sea. Monstril la pustulata san be distinguished by its body proportions and details of th e antennular armature and swimming legs. However, the most striking feature of this species is its cuticular ornamentation, with a dorsal patch of sma ll, blister-like processes on the head surface and other patches on the cep halothorax and on some pedigerous somites. The original description of Mons trilla brevicornis is complemented with new morphological data and is compa red with M. turgida Scott, also from the Indonesia region. This is the firs t monstrilloid species described as new from the southwestern Atlantic Ocea n.