LITHOTHAMNION PROLIFER FOSLIE - A COMMON NON-GENICULATE CORALLINE ALGA (RHODOPHYTA, CORALLINACEAE) FROM THE TROPICAL AND SUBTROPICAL INDO-PACIFIC

A little-known, but ecologically important non-geniculate coralline, L ithothamnion prolifer, is recorded from a number of tropical Indo-Paci fic sites, including Fiji, Australia, Kiribati and Indonesia. The spec ies occurs primarily on vertical walls of caves and overhangs in Fiji and Australia, but was also found as rhodoliths in Kiribati. Lithotham nion prolifer is characterized by the combination of characters which follow. The thallus is extremely glossy, smooth, and rosy coloured. Th alli usually produce complanate protuberances, but protuberances becom e terete when growing on well lit, horizontal substrata, when unattach ed, or when growing on loose substrata. Conceptacles occur mainly on t he tips of protuberances, and tetra/bisporangial conceptacles are larg e (to 1300 mu m external diameter, with chambers up to 1100 mu m diame ter). The tetra/bisporangial conceptacles are flush or only slightly r aised, and often extensive and irregularly shaped (resembling small so ri). They lack a raised rim, and have flattened pore plates. The roset te cells surrounding the tetra/bisporangial pore appear somewhat sunke n below the surrounding roof cells in SEM, and the cells of filaments lining the pore canals of tetra/bisporangial conceptacles do not diffe r from the cells of filaments making up the rest of the roof. Old conc eptacles persist and become buried in the thallus, and are then usuall y completely filled in by irregularly arranged calcified cells.