This work describes the first occurrence and abundance of larvae of M. longipinnis (Wey-mouth, 1910) in the Babitonga Bay estuary, southern Brazil. During an annual cycle (2007-2008), 144 plankton samples with cylindrical-conical net with 50cm in diameter (500μm mesh) and 72 samples with conical plankton net with 40cm in diameter (200μm mesh) were collected at nine stations. In addition, samplings were done with bottom trawl net (12mm mesh) at each station, aiming to collect juveniles and/or adults of M. longipinnis. Larvae occurred from February to May over a broad range area in Babitonga Bay. A to-tal of 7 larvae was collected, with average abundance of 5.4 larvae.100m -³. In sampling with bottom trawl, juveniles and adults were not recorded. Although recorded only in the ichthyoplankton, the results indicate, for the first time, the occurrence of M. longipinnis on the subtropical coast of Brazil, thus enabling a discussion on the ecology and sampling of these fishes with cryptic habits.