Hippasteria phrygiana (Parelius 1768)

Mah, Christopher L., 2023, New Goniasteridae and in situ observations significant to deep-sea coral predation, Memoirs of Museum Victoria 83, pp. 1-35 : 30

Hippasteria phrygiana (Parelius 1768)

Figure 15a–f

Asterias phrygiana Parelius 1768: 425 , see Mah et al. (2014) for full synonymy.

Hippasteria phrygiana H.E.S. Clark & McKnight, 2001:54 , pl. 13.

Hippasteria trojana Fell, 1958: 11 , pl. 1, figs A, G; 1959: 136, fig. 21; 1960: 61, pls. 2,3; 1962: 33; McKnight, 1967: 300; H.E.S. Clark, 1970: 3; A.M. Clark, 1993: 259; Rowe and Gates, 1995: 65; Koslow & Gowlett-Holmes, 1998: 44.

Diagnosis. Body stout, weakly stellate (R/r=1.69–2.0) arms short. Abactinal plates with a single, short conical spine or large, bivalve pedicellariae, which are surrounded by 6–20 enlarged quadrate to polygonal granules. Marginal plates 35–36 per interradius (arm tip to arm tip), each with 1–3 (mostly one) short, conical spines, but those interradially with two. Marginal plates otherwise bare with smooth surface. Bivalve pedicellariae on many, if not most, proximal marginal plates extending to the arm base, but absent on distalmost plates. Actinal intermediate region large with numerous bivalve pedicellariae, especially large on actinal plates adjacent to the adambulacral plates. Furrow spines, 1–3 (mostly 2), subambulacral spines, 1–3. All adambulacral spines robust, round in cross-section.Paddle-shaped pedicellariae large, one or two present immediately behind furrow spines.

Comments. These specimens are identical with H. trojana as originally described by Fell (1958) from New Zealand. NMV F307998 (Tasmania) is nearly identical to a New Zealand specimen (USNM E13768). This is one of multiple Hippasteria found to be morphotypes of the widely occurring species H. phyrgiana , present in the Atlantic, Pacific and Indian Oceans (Mah et al., 2014; Foltz et al., 2013). These morphotypes are consistent with species described from specific areas, including H. trojana .

Tasmanian specimens, while similar to those from New Zealand, were collected from much greater depths (1080– 1221 m).

Occurrence . Australian. Tasmanian Seamounts, Southeast of New South Wales, 1080–1221 m .

East of Peninsula , South Island, New Zealand, Chatham Rise, 402–585 m.

Outside of Australia – North Atlantic, North Pacific, Southern Indian Ocean, globally 10–1221 m.

Description – small form. Body weakly stellate, R/r=1.95, appearing nearly pentagonal. Arms triangular, interradial arcs wide, weakly curved. Abactinal surface with conical tubercles present along carinal plate series. Spines absent elsewhere, remaining surface covered by enlarged bivalve pedicellariae. Spines and pedicellariae and other abactinal plates with 3–10 widely spaced round to polygonal granules. Marginal plates, 18–20, with a single spine present on the central surface of each superomarginal and inferomarginal plate, with one or two plates per interradius with one or two extra tubercles or short spines. Marginal plate surface more strongly arched distally adjacent to terminus. Actinal plates each with a distinct bivalve pedicellaria that bisects the plate on which it sits. Granules, 2–10, round to polygonal, present around each actinal plate periphery. Furrow spines proximally three then two for remainder of arm series. Single, enlarged subambulacral spine present adjacent to furrow spines, adjacent to relatively small tong-like pedicellariae. Oral plate with furrow spines, four per side, with a single large spine projecting into mouth. All spines blunt. Oral plate with two series of paired granules, polygonal to quadrate in cross-section, along either edge of the diastema present between the two halves of the oral plate. Similar granules, 2–6, present on remainder of oral plate surface.

Material examined. NMV F307998 St Helens flat, Tasmanian seamounts, Tasmania, Australia, 41.2043° S, 148.788° E, 1221– 1202 m. Coll. A. Williams, A.A. Weber and R-L Erickson, 17 Dec. 2018. 1 wet spec , R=9.7 r=4.3.

NMV F123458 40 km East South East of Ulladulla , New South Wales, Australia. 35.5092° S, 150.882° E, 1080–1090 m. Coll. M. D. Norman, 16 May 1988. 1 wet spec , R=4.1, r=2.1.

USNM E13768 east of Banks Peninsula , South Island, New Zealand. 43.9° S, 174.598° E, 585 m. Coll. 27.viii.1971.1. Dry spec , R = ~10.1, r = 6.1.