Hydrasterias sexradiata (Perrier, in Milne-Edwards, 1882 )

Madeira, Patrícia, Kroh, Andreas, Cordeiro, Ricardo, De, António M., Martins, Frias & Ávila, Sérgio P., 2019, The Echinoderm Fauna of the Azores (NE Atlantic Ocean), Zootaxa 4639 (1), pp. 1-231 : 70

Hydrasterias sexradiata (Perrier, in Milne-Edwards, 1882)

Reports for the Azores:

Pedicellaster sexradiatus, Perrier, in Milne-Edwards, 1882 — $ Koehler 1909: 110–111, pl. 2, fig. 4; Mortensen 1921: 224, 1927a: 130; $ Sibuet 1972: 121; Pérès 1992: 254, 255;

Stellosphaera mirabilis Koehler & Vaney, 1906 a—? $ Koehler 1909: 131–136, pl. 24, fig. 1–10;

non Hydrasterias ophidion ( Sladen, 1889) — $ A.H. Clark 1949: 375 [misidentification];

Hydrasterias sexradiata (Perrier, in Milne-Edwards, 1882) — Gage et al. 1983: 285–286; A.M. Clark & Downey 1992: 410, figs. 62c–d; García-Diez et al. 2005: 48; Dilman 2006: 185, 2008: 147, 2013: 583, 2014: 37–38.

Type locality: off Portugal (between c. 40°N– 38°N, 12°W) .

See: Perrier (in Milne-Edwards 1882: 46–47; 1894: 100–102, pl. 9, fig. 2, as Pedicellaster sexradiatus ); A.M. Clark & Downey (1992).

Occurrence: NE Atlantic, from the Rockall Trough ( Gage et al. 1983) and the Bay of Biscay ( Perrier 1894), southwards to? Cape Verde ( Mortensen 1927a) and on the Mid-Atlantic Ridge from the Reykjanes Ridge ( Dilman 2006) to the Azores ( Koehler 1909).

Depth: 599– 4,260 m (A.M. Clark & Downey 1992); AZO: 599– 3,465 m ( Koehler 1909).

Habitat: soft substrates, from ooze to sand ( Koehler 1909).

Larval stage: planktotrophic ( Mortensen 1921).

Remarks: Koehler (1909) identified specimens of ‘ Stellosphaera mirabilis ’ collected by Princesse Alice, at stations located within Azorean waters. Mortensen (1921, 1927a) believed that this was actually the larval form of H. sexradiata , in an advanced stage of metamorphosis. According to A.M. Clark & Downey (1992), this is yet to be confirmed. The western Atlantic Hydrasterias ophidion was reported from the Azores by A.H. Clark (1949), based on his identification of material collected by Atlantis (sta 20: 37°50’30”N, 26°00’00”W, 2,562 m). Later, Dilman (2014) placed A.H. Clark’s material under H. sexradiata , a known native to the Azorean deep waters. Additionally, the inclusion of Cape Verde Archipelago in the geographical distribution of Hydrasterias sexradiata in the bibliography (e.g., Mortensen 1927a; A.M. Clark & Downey 1992) is possibly based on a misprint by Koehler (1909), who remarked that the material of this species was collected by Princesse Alice between the Azores and Cape Verde, though all listed stations are positioned in the Azores region.