The genus Macrophiothrix (Ophiuroidea : Ophiotrichidae) in Australian waters

Abstract

The genus Macrophiothrix H. L. Clark, 1938, includes some of the largest and most common ophiuroids occupying cryptic habitats in tropical Australia. Taxonomy of the Ophiotrichidae is confused and the species of Macrophiothrix, in particular, have been difficult to identify. Range of variation of certain characters within species has been determined by examination of a large number of specimens. Shape of the dorsal arm plates and form of the disc stumps are reasonably reliable diagnostic characters within adults of most species. Many taxonomic characters were found to vary in a consistent manner between small and large individuals of a species. A group of character states common to small specimens of most species is identified. In Australian waters, 17 species of Macrophiothrix (including two new species and four species newly recorded from Australia) are now recognised.