On the red algal genera Grallatoria Howe and Callithamniella Feldmann-Mazoyer (Ceramiales)

Grallatoria Howe (1920) (Ceramiaceae, Rhodophyta), with a single species, G. reptans, was described from the Bahamas and has not been reported upon again. Recent collections of fertile material from St Croix, U.S. Virgin Islands, show that the genus is identical with and its name antedates Callithamniella Feldmann-Mazoyer (1938). The two described species of Callithamniella, C. tingitana (Schousboe ex Bornet) Feldmann-Mazoyer and C. flexilis Baardseth (1941) are transferred to Grallatoria. Grallatoria is distinguished by a dorsiventral construction where nearly every cell of a decumbent axis bears conspicuous coloured haptera on the ventral surface, and opposite these on the dorsal surface one branch of determinate and one of indeterminate growth. Tetrasporangia, either cruciately or tetrahedrally divided, were known in the described species of Callithamniella and in G. reptans, and spermatangia were known only in C. flexilis. Cystocarps are described here for the first time. The reproductive and vegetative characters suggest relationship to the tribe Sphondylothamnieae of the Ceramiaceae (Ceramiales).