Rhipidaster Sladen, 1889

Mah, Christopher L. & Fujita, Toshihiko, 2020, New species and occurrence records of Japanese Solasteridae and Ganeriidae including a new species of Paralophaster from the North Pacific with an overview of Hyalinothrix, Zootaxa 4750 (1), pp. 67-100 : 77

Rhipidaster Sladen, 1889

Rhipidaster Sladen, 1889: 447 .

Rhipidaster (Xenorias) Fisher, 1913: 222 .

Xenorias Fisher, 1919: 451 .

Comments. It is argued herein that Xenorias Fisher, 1913 is a junior synonym of Rhipidaster Sladen, 1889 . Fisher (1913, 1919) differentiated Xenorias from Rhipidaster based on the position of the marginal plates, which he argued formed oblique rather than parallel chevrons (in Rhipidaster ) with one another, touching by the inter marginal ends along the side of the ray. Re-examination of these plates on dry specimens showed that the superomarginal and inferomarginal plates were in contact with articulated ends intermarginally permitting flexure. Thus, both parallel and oblique marginal plate arrangements are possible, in many cases on the same arm of a single individual.

Although Rhipidaster was not included in the most phylogenetic revision of the Valvatacea ( Mah & Foltz 2011), the possession of multiple arms suggests greatest affinity with Solaster or Crossaster ( Fig. 1 ).

Figures

FIGURE 1. Simplified tree showing relationships between the Solasteridae, Asterinidae and Ganeriidae from Mah & Foltz (2011).