ASTEROMENIA (RHODYMENIACEAE, RHODYMENIALES), A NEW RED ALGAL GENUS BASED ON FAUCHEA-PELTATA

Asteromenia gen. nov. (Rhodymeniales, Rhodophyta) is proposed with a s ingle species, Asteromenia peltata (W. R. Taylor) comb. nov. (basionym : Fauchea peltata W. R. Taylor). Thalli of the proposed new genus are stipitate with dorsiventral, peltate blades that are initially circula r in shape but with age become stellate wish ligulate arms. Internally , the blades have a polystromatic medulla of large, hyaline cells, gra ding into a cortex of smaller, pigmented cells. Clusters of translucen t cells occur On the dorsal surface of the blade. Tetrasporangia are f ormed by transformations of intercalary midcortical cells. Mature tetr asporangia have cruciately arranged spores and are densely aggregated in the cortex, mostly on the ventral surface, but occasional tetraspor angia also arise on the dorsal surface. Carpogonial branches are four- celled and arise on inner cortical cells. Auxiliary cells are borne on auxiliary mother cells attached to supporting cells of the carpogonia l branches. Cystocarps are protuberant, with well-developed, ostiolate pericarps that often have extended, proboscis-like necks. The new gen us differs from the previously described peltate or dorsiventral taxa in the Rhodymeniaceae by Its polystromatic medulla (Maripelta and Scia dophycus have a monostromatic medulla), intercalary tetrasporangia for med In an unmodified cortex, and four-celled carpogonial branches (Hal ichrysis, as typified by H. depressa (J. Agardh) F. Schmitz, has termi nal tetrasporangia in nemathecia and three-celled carpogonial branches ).