Bredin-Archbold Smithsonian Biological Survey of Dominica: Burrowing sponges, Genus Siphonodictyon Bergquist, from the Caribbean

Siphonodictyon (Adociidae, Porifera) was hitherto known only from one species (Siphonodictyon mucosum Bergquist) from the Pacific Ocean. In the present paper the species is recorded also from the Indian Ocean. Two new species (Siphonodictyon cachacrouense, new species and Siphonodictyon coralliphagum, new species) are described from the Caribbean Sea. Based on morphological differences Siphonodictyon coralliphagum is divided into four forms (forma typica, forma obruta, forma tubulosa and forma incrustans). All species excavate burrows in coral skeletons. Another Caribbean species with sand-burrowing habit (Siphonochalinasiphona de Laubenfels)  is here transferred to Siphonodictyon. Based on the new material the definition of the genus is revised. Histological features and ecological data are discussed for all species.