Biochemcal and morphometric differences of two sympatric sibling species of Clathria (Porifera : Demospongiae : Microcionidae) from northern Australia

Abstract

Two cryptic sympatric species of Clathria were discovered incidentally during an electrophoretic study of 62 poecilosclerid and axinellid species. Subsequent investigations on the carotenoid pigment characteristics and antibiotic activity of 37 species, and free amino acid composition of 30 species confirmed those differences, but only very few morphological features of questionable importance could be used consistently to differentiate taxa (C. lendenfeldi Ridley and Dendy and C. major Hentschel): thickness and geometry of toxa microscleres, presence or absence of apical spination on a variable proportion of auxiliary megascleres, and statistical (but not absolute) differences in the mean sizes of many spicule categories. Biological and biochemical characteristics and population variability of both species are briefly described, and the significance of cryptic characters to the existing morphological systematics of Microcionidae is discussed.