Hymenaster pellucidus Thomson, 1873

Reports for the Azores:

Hymenaster pellucidus Thomson, 1873 — $ Perrier 1896a: 40; García-Diez et al. 2005: 47; $ Dilman 2008: 142; Dilman 2014: 35.

Type locality: Faeroe Channel (60°21’N, 05°41’W).

See: Sladen (1889: 521–522, pl. 92, figs. 6–7, pl. 93, figs. 10–12); A.M. Clark & Downey (1992: 319–320, figs. 50a–b, pl. 77, figs. C–D).

Occurrence: circumboreal, in the Atlantic and Pacific Oceans (Clark & Downey 1992); in the Atlantic from the Arctic waters (Koehler 1909) south to northern South America (c. 7°N; Clark & Downey 1992) in the West Atlantic and south to Portugal in the East Atlantic, and in the Mid-Atlantic Ridge from the Reykjanes Ridge and the Charlie- Gibbs Fracture Zone to the Azores (Dilman 2008).

Depth: 13– 3,240 m (Dilman 2008); AZO: 2,870 –3,050 m (Perrier 1896 a, Dilman 2008).

Habitat: soft (ooze, mud sand, shell-sand, gravel) to hard substrates (Perrier 1896 a, Sneli 1999).

Larval stage: lecithotrophic (brachiolaria larvae), brooded internally until late juvenile stage is reached (approximately one month; Janies 1995).

Remarks: the first report of Hymenaster pellucidus from the Azores by Perrier (1896a; Hirondelle, sta 248: 41°40’41”N, 26°44’9”W, 2,870 m; specimens lost) was considered doubtful by later authors (e.g., Koehler 1909, 1924; Mortensen 1927a; Grieg 1932) as it was generally considered an exclusively Arctic cold-water species. However, Dilman (2008) recently identified this species among the material collected from the Mid-Atlantic Ridge in northern Azorean waters (G.O. Sars, MAR–ECO cruise, sta 46/372: 42°46’N, 29°16’W, 3,005 –3,050 m) thus substantiating the presence of this species in the archipelago.