Sanidaster in Freshwater Sponges: an unexpected spicule for the birotuled Genus Corvoheteromeyenia Ezcurra de Drago, 1979

Corvoheteromeyenia Ezcurra de Drago, 1979 is exclusively known from Neotropical Region with two species recorded: C. australis (Bonetto & Ezcurra de Drago, 1966) and C. heterosclera (Ezcurra de Drago, 1974). The genus is characterized by the presence of birotuled gemmuloscleres inserted radially embedded in the gemmule, by megascleres which are exclusively oxeas, occasionally sparsely microspined and pseudobirotuled microscleres present in two distinct series. A total of twelve specimens were collected in São Francisco Basin (Bahia State, Brazil) and identified as belonging to C­orvoheteromeyenia. Based on this material, we record C. heterosclera for São Francisco Basin. Additionally, we describe a new species of Corvoheteromeyenia that differs from other species of genus by having gemmulosclere sanidaster. Sanidaster display an intermediate morphology between the birotule and rodlike (acanthostrongyle) spicular type. The gemmulosclere sanidaster found here could be interpreted as malformations due to environmental conditions, since malformations in gemmuloscleres had previously been observed in experimental conditions in some freshwater sponges exposed to heavy metal. However, in these conditions only 50% of gemmoscleres were malformed, and in C. sanidastosclera n. sp., 100% of gemmoscleres were sanidasters. Thus we do not believe that this morphology of spicules was the result of exposure to chemical compounds in the environment. This result reinforces the idea of Penney & Racek (1968) that the segregation of Spongillidae Gray, 1867 into two groups based on the form of gemmoscleres as proposed by Vejdovsky (1887) is no longer justified.