Hippasteria mcknighti Mah et al. 2014

Mah, Christopher L., 2023, New Goniasteridae and in situ observations significant to deep-sea coral predation, Memoirs of Museum Victoria 83, pp. 1-35 : 28

Hippasteria mcknighti Mah et al. 2014

Figure 14a–e

Diagnosis. Body stellate (R/r = 1.85– 2.27), disk tumescent, confluent with triangular arms.Abactinal surface ornamentation is primarily composed of widely spaced tubercles and pedicellariae, large and homogenously sized, covering abactinal surface. Tubercles, smooth, thickened, and short, sit on bases surrounded by distinct, wide fasciolar grooves. Marginal plates, 40 per interradius (at R = 6.1 to 7.5), quadrate in shape. Each plate has 1–5 large but squat cone-shaped tubercles, and one or two (mostly one) large bivalve pedicellaria. Granules coarse, closely distributed, rounded to angular in shape, especially on actinal surface. Actinal plates covered by large, squat tubercles and large bivalve pedicellariae (1–2 mm in length). Furrow spines, blunt, two or three (mostly two) per plate, each spine flattened and oval in cross-section. Subambulacral spines, blunt, 1–3, in transverse series, often thick and triangular to quadrate in cross-section, thicker than furrow spines but about 80–90% of furrow spine length.

Comments. This species shows close affinities with H. heathi , as outlined by Mah et al. (2014), and is largely consistent with the species description therein. The actinal surface, showing the rounded tubercles and the obliquely angled bivalve pedicellariae, are nearly identical. In contrast, the abactinal tubercles on this specimen are significantly smaller than on the holotype.

Occurrence . Australia. Tasmanian seamounts, 817 m. New Zealand, 720–1015 m .

Material examined. NMV F240217 Mongrel (southern) seamount, Tasmania, Australia. 44.2569° S, 147.114° E, 817 m. Coll . R. Thresher and D.A. Staples , RV Thompson with ROV Jason , 23 Dec 2008. 1 wet spec . R=8.4, r=4.1.