The unusual prodissoconch and larval development of Barbatia bailyi (Bartsch, 1931) (Mollusca: Bivalvia: Arcidae)

In this study, the prodissoconch and developmental mode of the bivalve Barbatia bailyi are described for the first time. Barbatia bailyi has a large and unusual "hat-shaped" prodissoconch, a form which has appeared only in scattered reports in the literature. Based on observations of live and preserved specimens, this prodissoconch morphology is linked to a non-planktonic, brooded larval developmental mode. This prodissoconch morphology appears in at least two other undescribed species in the genus Barbatia (subgenus Acar), suggesting that brooded development may be a frequent occurrence in this subgenus.