Pachyrotula , a new genus of freshwater sponges from New Caledonia (Porifera: Spongillidae)

--eharacteristics found during a review of the type material of Spongilla (StratospongiLIa) raceki ~iitzler from New Caledonia point to a new, monotypic genus, Pachyrotula. This new genus is closely related to Heterorotula Penney & Racek and to Houssayella Bonetto & Ezcurra De Drago. Heterorotula also occurs .in New Caledonia and is represented by the species H. caledonensis new species and H. multidentata (Weltner). These species, along with Oncosclera diahoti (Riitzler), new combination, are indicators of a rare and particular freshwater sponge fauna of this island. For the past three decades, the freshwater sponges of New Caledonia have been known only from the specimens described by Riitzler (1968). It recently became clear that this material needed to be reexamined, especially in the light of Penney & Racek's (1968) comprehensive study of all gemmule-producing genera of freshwater sponges and Racek's (1969) extensive work on Australia's freshwater sponges, which provided new insight into the generic and specific relationships of these faunas and revealed their heretofore unsuspected richness. That work and several subsequent studies on the freshwater sponges of South America indicated the need for a taxonomic and systematical updating of the New Caledonia description. As a result of this updating, a new genus is being proposed, with Spongilla (StratospongiLIa) raceki Riitzler as the type species; also, Ephydatia multidentata (Weltner) forma caledonensis Riitzler is elevated to a full species in the genus Heterorotula Penney & Racek, and Spongilla (StratospongiLIa) diahoti Riitzler is transferred to the genus Oncosclera Volkmer-Ribeiro. Material and Methods The material examined consisted of types and paratypes of Spongilla (Stratospongillay diahoti, S. (StratospongiLIa) raceki, and Ephydatia multidentata f. caledonensis (Riitzler 1968), all deposited at the National Museum of Natural History, Washington D.C. (USNM); slides of Houssayella iguazuensis Bonetto & Ezcurra de Drago, 1966, provided by I. Ezcurra de Drago; and slides of species of the genus Heterorotula provided by A. A. Racek; the latter deposited at Museu de Ciencias Naturais (MCN) of Fundayao Zoobotanica do Rio Grande do SuI, Porto Alegre, Brazil. A minute fragment of Spongilla (S.) raceki with gemrnules was dissociated after boiling in nitric acid and washed several times in distilled water. When completely dry, the suspended clean spicules were dropped on a stub and coated with gold in preparation for scanning electron microscopic (SEM) observations. Some dry gemmules were hand-sectioned under a stereomicroscope and their halves glued to a stub and also gold-coated for SEM examination. Photomicrographs were obtained with an I