Use of cement for attachment in Neocalceostomoides brisbanensis, a calceostomatine monogenean from the gill chamber of the blue catfish, Arius graeffei.

The thin, weakly muscular, disc-shaped haptor of the calceostomatine monogenean Neocalceostomoides brisbanensis is attached to surfaces in the gill chamber of its catfish host by cement. It is unlikely that any suction is generated (there are no muscular loculi) and the hooks are reduced in size. Two distinctive secretions are associated with the haptor: a finely granular secretion from glandular tissue within the haptor and anterior to it, which enters the dorsal haptor tegument near the periphery of the disc and spreads throughout the ventral haptor tegument; a coarser secretion produced in the peduncle and posterior region of the body, which finds its way to gland openings near the hamuli via centrally situated large and small haptor reservoirs. It seems most likely that the tegumentary secretion is the cement, but other possibilities are discussed. It is suggested that the increasing importance of cement for haptor attachment in calceostomatines has led to the development of a weakly muscular, foliaceous haptor and a progressive reduction of the hooks.