Molecular Systematics and Morphological Analyses of the Subgenus Setihenricia (Echinodermata: Asteroidea: Henricia) from Japan
Th e subgenus Setihenricia Chichvarkhin and Chichvarkhina, 2017 currently consists of 32 out of 94 species of sea stars in the genus Henricia Gray, 1840. However, only 10 have been molecularly ascertained as to the phylogenetic position. Based on seven mitochondrial gene markers (16S rRNA, COI, tRNA-Ala, tRNA-Leu, tRNA-Asn, tRNA-Gln, and tRNA-Pro), we performed molecular analyses to assess the monophyly of Setihenricia using 16 species of Henricia from Japanese waters, as well as other
... for which sequences were available in public databases. Th e monophyletic Setihenricia was only weakly recovered because the support values were low, but we assume this taxon may be valid in consideration of a morphological key. Henricia kinkasana Hayashi, 1940 is herein identifi ed as a new member of Setihenricia , based on molecular and morphological evidence. Sequences in the public databases previously identifi ed as H. compacta (Sladen, 1889) and H. obesa (Sladen, 1889) were nested in the Setihenricia clade; these two species are also likely members of Setihenricia . Our morphological assessment yielded three fi ndings: (1) the number of the rows of spines on each inferomarginal plate, being three or more, appears to be a useful diagnostic character for Setihenricia , as has been suggested in previous studies, (2) the degree of spine tapering turned out to be less relevant in diagnosing the subgenus than previously supposed, (3) two newly introduced characters-( i ) the width of adambulacral plates and ( ii ) the ratio of two measurements in ambulacral plates to the length of interradius-may be eff ective to distinguish members of this apparent Henricia subclade from other members of the genus.