Trichocytes in L ithophyllum kotschyanum and L ithophyllum spp. ( C orallinales, R hodophyta) from the NW I ndian O cean

The current diagnosis of the genus L ithophyllum includes absent or rare trichocyte occurrence. After examining holotype material, single trichocytes have been revealed to occur abundantly in L ithophyllum kotschyanum U nger, and in freshly collected specimens of L ithophyllum spp. from the R ed S ea, G ulf of A den and S ocotra I sland ( Y emen). Trichocyte occurrence is not considered a diagnostic character at specific or supraspecific levels in the L ithophylloideae, and the ecological significance of trichocyte formation is discussed. The generitype species, L . incrustans P hilippi, does not show trichocytes nor do many other L ithophyllum species from diverse geographic localities, but the presence of abundant trichocytes in other congeneric taxa requires emendation of the genus diagnosis. Therefore, the diagnosis of L ithophyllum is here emended by eliminating the adjective “rare” in the sentence concerning trichocyte occurrence, as follows: “ T richocytes present or absent, if present occurring singly.”