Ultrastructural observations on marine choanoflagellates (Choano-flagellida, Acanthoecidae) from the coast of Thailand: species of Apheloecion gen.nov

Three species of loricate choanoflagellates (Choanoflagdlida,Acanthoecidae), collected from the Andaman Sea near Phuket Island(SW Thailand), have been described and referred to Apheloeciongen.nov. (holotype: A. quadrispinum sp.nov.). All species possessa single-chambered lorica composed of one transverse costs overlaidby a limited number of longitudinal costae which converge posteriorly.Anteriorly the longitudinal costae protrude above the transversecosta as sharp pointed spines. In A. quadrispinum sp.nov. andA. pentacanthum sp.nov. the lorica is terminated by a shortposterior spine, whereas in A. articulatum sp.nov. the pedicelis much more prominent, consisting of several costal stripswhich are joined end-to-end. The species of Apheloecion appearto be most closely related to species of Calliacantha and Monocosta.None of the species described are so far known from localitiesoutside the Andaman Sea.