Hippasteria imperialis Goto 1914

Mah, Christopher L., 2015, New species, corallivory, in situ video observations and overview of the Goniasteridae (Valvatida, Asteroidea) in the Hawaiian Region, Zootaxa 3926 (2), pp. 211-228 : 224

Hippasteria imperialis Goto 1914

Goto 1914: 338; Hayashi 1942: 338; 1973: 6, 15; Imaoka et al., 1990: 50; Mah 1996; Fujikura, et al. 2008: 272 (as H. imperialis )

Grigg 1987: 387 (as Hippasteria spinosa )

Chave & Malahoff 1998: 43, 86 (as Cryptopeltaster )

Occurrence. Sagami Bay/Tosa Bay region, Kii Strait, southern Japan, Hawaiian Islands. 245– 600 m.

Taxonomic comments. Based on specimens collected from the Hawaiian region (see below) a second Hippasteria sp., which is consistent with the description of Hippasteria imperialis Goto 1914 has been identified. Images from Chave & Malahoff (1998) show this species but have misidentified it as “ Cryptopeltaster sp.” However, Hippasteria imperialis , as discussed by Mah et al. (2014), may be a morphological varaint, and thus a synonym, of Hippasteria phrygiana . However, given the fact that only a single sample of this species was included in the analysis and that it demonstrates a very unusual level of morphological distinctiveness from all other Hippasteria phrygiana , further work is needed to verify its proper status.

In situ observations. Hippasteria imperialis has not been observed actively feeding but some circumstantial evidence suggests it too may feed on deep-sea corals (i.e. octocorals). Three images (M-066-047, M-146-020, M- 148-004) show this species close to a small sized isidid octocoral and amidst misarticulated remains of isidids visibly scattered among the sediment. This may represent evidence of predation by this species on deep-sea octocorals.

Material examined. CASIZ 102006 6 miles offshore from Makapuu Point. Oahu, Hawaii. 396 m (1300 ft). Coll. S. Earle, B. Bartko fr. Deep Star II. 25 Oct 1979 (1 dry spec.R=12.5, r=7.6); BPBM W3826, Southeast Oahu, off Makapuu Point, 365 m. Coll. B. Madden, 1 July 1975. (1 wet spec. R=2.4, r=1.5)

Video observations. Makapuu, Oahu: M-066-047: 21.3, -157.55, 355 m; M-146-020, M-148-004: 21.306, - 157.54, 367 m;