Marginaster paucispinus Fisher, 1913

Mah, Christopher L., 2023, New occurrence of Poraniidae (Valvatacea, Asteroidea) in Australia with a new genus and species from deep-sea settings, Memoirs of Museum Victoria 82, pp. 119-131 : 125

Marginaster paucispinus Fisher, 1913

Marginaster paucispinus Fisher 1913: 407 .— Jangoux and Aziz 1988: 633, 646.— McKnight 2006: 107.— Lee et al. 2017: 274.

Marginaster sp. McKnight 1968: 513.—H.E.S. Clark 1970: 5.— McKnight in H.E.S. Clark and McKnight 2001: 166.

Diagnosis. Body pentagonal to weakly stellate (R/r=1.1–1.7), body thick, arms triangular, interradial arcs weakly curved. Abactinal skeleton reticulate with relatively wide openings ( Fig. 2c). Transverse ribs on arms projecting from radial series ( Fig. 2a, c). Marginal plates, 10–11 per interradius ( Fig. 2a, c, d), each plate with 1–4 short, blunt, conical spinelets ( Fig. 2a, b). Superomarginals and inferomarginals (6–7), inferomarginals forming flange-like ambitus, each with 4–5 webbed, flattened spatulate spines. Upper inferomarginal plate surface with 3–4 small spinelets. Actinal plates forming reticulate arrays that track from adambulacral plates to the inferomarginals to the abactinal surface. Open meshes between these plates. Furrow spines (1–2) ( Fig. 2b, c), two subambulacral spinelets, narrowly spatulate.

Comments. Marginaster paucispinus has been widely recorded geographically and in depth (155–700 m) across the Indo-Pacific. Some characteristics – such as marginal plate number and marginal plate spine number, as well as abactinal plate arm patterns – appear to be consistent among individuals surveyed, whereas the two MNHN specimens from the Austral Islands and the South Pacific appear to show a more developed dermal layer. The reticulate skeleton pattern shows a similar pattern to other Indo-Pacific individuals, including the holotype. McKnight (2006) remarked on the similarity between individual M. paucispinus and also with other Marginaster spp.

This species is distinguished from the Atlantic Marginaster species based primarily on the lower marginal plate number per interradius (approximately 10–11) than in Marginaster pectinatus (15–20) and M. capreensis (approximately 12 or more). Number and position of marginal spines also differed but did show some overlap. A full overview was beyond the scope of this work, but based on taxonomic summaries of these species (e.g. Clark and Downey, 1992), their characteristics are very similar, suggesting further sampling could blur boundaries between established species concepts.

Occurrence. Australia. The Great Australian Bight , South Australia, 155–191 m.

Outside Australia. South China Sea, near Hong Kong (183 m), Korea, Reunion Island and Kermadec Islands (179– 227 m), northern New Zealand (518–554 m). 179–554 m.

New Records: Austral Islands and the South Pacific, 480– 700 m.

Material examined. NMV F 240386 , Great Australian Bight , South Australia, - 33.3366° S, 130.257° E, 188–191 m. Coll. IN 2015_C02 GAB BP Expedition – Ichthyology Team, IN 2015_C02 GAB BP Expedition – Marine Invertebrates Team. 15 Dec 2015. 1 wet spec . R=0.5, r=0.3.

IE-2013-1518 Austral Islands , northeast of Rapa Its, South Pacific - 27.566667° S, 144.27° W, 480–700 m. Coll. BENTHAUS DW 1897. 2 wet spec. R =1.6, r=1.4; R=0.4, r=0.35.

IE-2013-4675 South Pacific , south of Niue, - 25.283333° S, - 168.933333° W, 609–691 m. Coll. NORFOLK 2 DW 2064. 1 wet spec. R =0.7, r=0.4.

Holotype, M. paucispinus . USNM 32641 Approximately 250 km southeast of Hong Kong, South China Sea. 21.55° S, 116.217° E, 183 m. Coll. USFC Steamer Albatross, 4 Nov 1908. 1 wet spec. R =1.1, r=0.8.