A taxonomic reassessment ofSpongites(Corallinaceae, Rhodophyta) based on studies of Kützing's original collections

Results from critical studies of the original collections upon which Spongites Kützing, 1841 is based have led to the designation of S. fruticulosa as lectotype species and to the resurrection and recognition of Spongites as a distinct genus of Corallinaceae (Rhodophyta). Spongites is characterized by the absence of geniculae, uniporate tetrasporangial conceptacles, a multistratose non-palisade and non-coaxial medulla (“hypothallium”) and cortex (“perithallium”), fusions between cells of adjacent filaments, and trichocytes which are solitary or arranged in a vertical series. Since at least 1883, the Kützing epithet “fruticulosa” has been misapplied widely to a taxon with multiporate tetrasporangial conceptacles, whereas the type collection of S. fruticulosa possesses uniporate tetrasporangial conceptacles. Of the six original species, three (S. fruticulosa, S. racemosa, S. stalactitica) are retained in Spongites; S. dentata is referred to Lithophyllum and S. nodosa to Lithothamnion as distinct species; and S. confluens is regarded to be conspecific with Lithophyllum incrustans Philippi. Detailed morphogological-anatomical accounts of specimens in the type collections are presented along with relevant historical data on the genus and on the various species studied. The relationships of Spongites to Neogoniolithon and to other genera of Corallinaceae also are discussed.