Systematics of Himerometra (Echinodermata: Crinoidea: Himerometridae) based on morphology and molecular data

One of the most common genera of feather stars found on tropical Indo-western Pacific reefs, Himerometra A.H.Clark, 1907, has previously included six accepted species, distinguished chiefly by variations in the enlarged proximal pinnules. This study examined new and existing specimens using molecular (mtDNA and nuDNA) techniques and morphological characters to revise the genus. Both approaches support placing H. magnipinna and H. martensi as junior synonyms of H. robustipinna . Sequence data for specimens attributed to H. bartschi also place this species as a junior synonym of H. robustipinna , despite some morphological disparity. Himerometra sol is retained as distinct despite morphological congruence with H. robustipinna , because the two known specimens were collected outside the known range of the latter, with no molecular data currently available. Himerometra persica is herein transferred to Heterometra : the type specimens were incorrectly identified. The species treated as valid are redescribed. This study illustrates the importance of re-examining crinoid species boundaries for established taxa without molecular corroboration and demonstrates that diversity in this particular feather star clade might be lower than previously thought.