Reproductive Mode of Corbicula tobae (Martens, 1900): Brooding and Larval Morphology in Lake Toba (Indonesia)

Abstract

Currently, the reproductive mode of the Indonesian endemic species Corbicula tobae from Lake Toba is yet to be investigated. In this study, we describe, for the first time, the reproductive mode of this endemic species based on a series of topotype specimens, combining anatomical and histological data. According to our data, C. tobae is a dioecious species, incubating D-shaped larvae in the inner demibranchs and having monoflagellate sperm. The head of the C. tobae spermatozoon differs from those of other Indonesian species of Corbicula by having the smallest length. A histological investigation of C. tobae gills revealed that the inner demibranch has larger interlamellar spaces compared with the outer demibranches. Our study highlights several specific reproductive traits may have evolved in narrowly endemic Corbicula clams within their native ranges.