Larval development of Brachidontes solisianus (Bivalvia, Mytilidae), with notes on differences between its hinge system and that of the mollusk Perna perna.

This work, which is part of a study program on meroplankton larvae, aims to gain more in-depth knowledge about planktonic larvae. This study began with the mollusk Brachidontes solisianus (Bivalvia-Mytilidae), which is abundant on the rocky shores of the Cabo Frio region (state of Rio de Janeiro, Brazil). Brachidontes solisianus larvae were grown under controlled conditions for a period of 26 days and were fed with Isochrysis galbana and Tetraselmis chui. The temperature was kept at 26 degrees C and the saltiness at 28. Images of the larvae were taken daily with a light camera and measured with a micrometric lens until settlement occurred. The average size of the first D-shaped veliger stage was 90 microm in length and 70 microm in height, while the size in the last stage before settlement (pediveliger) was 273 microm in length and 257 microm in height. The comparative study of the hinge system involved the most abundant intertidal species of the study area: Brachidontes solisianus and Perna perna. The B. solisianus species were found to have more visible denticles at the extremities of the provinculum, whereas the denticles of the P. perna species occur along the entire provinculum.