SOLASTERIDAE Viguier 1878

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 : 69

SOLASTERIDAE Viguier 1878

Multi-armed solasterid genera such as Crossaster and Solaster occupy important ecological roles as predators (see Mauzey et al. 1968; Carlson & Pfister 1999; among others) and display importance in influencing community structure (e.g., Himmelman & Dutil 1991). Some five-rayed solasterids, such as those in the genus Lophaster are also predators (e.g., Duncan & Sladen 1889; Mah pers. obs.) but are not as well understood. Solasterids include a total of 52 species in ten genera, which occur primarily in cold to temperate water habitats ranging from intertidal to abyssal (> 3000 m) depths. The Solasteridae includes nine living genera in addition to the Jurassic Brachisolaster . Fisher (1911) provided one of the last comprehensive keys to the genera within the Solasteridae .

In the Japanese region, initial accounts of Japanese solasterids included those of Sladen (1889) and Fisher (1911). Hayashi (1939, 1940) provided comprehensive descriptions and identification keys to Solaster and Crossaster species from Japanese waters. Hayashi (1973) described a new species, Lophaster asiaticus , which was also the first account of Lophaster from Japanese waters. Imaoka et al. (1991) was the first to identify Lophaster furcilliger Fisher, 1905 , a species previously known from the Pacific coast of North America and the Aleutians, from the Japan Sea. More recently Kogure & Kaneko (2010) described Seriaster regularis from Okinawa and provided a key to Japanese solasterids (in Japanese).

Comprehensive molecular phylogenetic treatments of the Solasteridae have not yet been undertaken, but both the two- and three-gene trees in Mah & Foltz (2011) support five-rayed forms, such as Lophaster and Paralophaster , as relatively relative to multi-rayed forms such as the more derived Crossaster and Solaster . Although the position of the “traditional” Ganeriidae (sensu Spencer & Wright 1966) is not completely understood, its position on proximal locations on the broader clade are relevant to the Solasteridae as potential sister taxa given shared synapomorphies between some ganeriids and basal solasterids.

Diagnosis. Body stellate, disk thick, well defined arms, 5 to 15, round in cross-section. Abactinal surface composed of lobate plates in irregular reticulum, displaying variably close to wide articulation with single to large papular expression. Plates with variable accessories ranging from spines to paxillae. Marginal plates present in two series (following Blake 1978), but one or both series show variable degrees of expression resembling abactinal plates or paxillae. Actinal plates restricted to disk in most taxa. Adambulacral plates wing-like, forming transverse series with interadambulacdral plate spaces filled with tissue. Adambulacral plate surface with variable spine expression projecting into furrow. Subambulacral spination variably expressed as individual spines, in tufts or as combs.