| abstract | Amongst the vagile epifauna on the mangrove trees Avicennia marina and Rhizophora stylosa, Acari numerically play an important role, contributing 20-75% of the fauna. The two major groups are the prostigmatids and oribatids. Amongst the prostigmatid mites, halacarids are regularly present from the upper littoral fringe, inundated only at very high tide, to the permanently wet substrata adjacent to tide pools. Oribatids are most abundant in permanently wet substrata and often dominate the mite fauna. Five halacarid species, regularly found amongst the epibios on mangroves, are described, Isobactrus australiensis n. sp., Rhombognathus ocularis n. sp., Agauopsis dasyderma n. sp., Copidognathus lutarius n. sp. and C. piger n. sp. Isobactrus australiensis often is the only mite in the upper zone not reached by every high water. |