Plutonaster notatus $ Sladen, 1889: 97–99, pl. 14, figs. 6–7, pl. 15, figs. 5–6; Perrier 1894: 318–319; $ Perrier 1896a: 49; $ Koehler 1909: 17–18, pl. 3, fig. 5, pl. 10, figs. 7–12, 1921a: 2; Mortensen 1927a: 63;
Plutonaster abbreviatus $ Sladen, 1889: 99–100; Perrier 1894: 313; Mortensen 1927a: 63;
Plutonaster inermis (Perrier, 1885c) — $ Perrier 1896a: 49;
Plutonaster granulosus Perrier, 1891 — $ Perrier 1896a: 49–50, pl. 4, figs. 2, 2a–2d;
Plutonaster rigidus Sladen, 1889 — $ Koehler 1909: 19–22, pl. 4, fig. 6, pl. 10, figs. 5–6, 1921a: 2; Mortensen 1927a: 63;
Plutonaster agassizi Verrill, 1880 — Grieg 1932: 14–15, pl. 4, figs. 2–4;
Plutonaster agassizi notatus Sladen, 1889 — $ A.M. Clark & Downey 1992: 70–71, pl. 17, figs. C–E; García-Diez et al. 2005: 46–47; $ Dilman 2008: 134–135.
Type locality: Azores (38°30’N, 31°14’W).
See: A.M. Clark & Downey (1992); Dilman (2008).
Occurrence: Northeast Atlantic, from the Charlie-Gibbs Fracture Zone in the Mid-Atlantic Ridge and off SW Ireland (c. 53°N, 20°W) to the Bay of Biscay and the Azores (A.M. Clark & Downey 1992), possibly in the Canaries and Madeira as well (Perrier 1894, Koehler 1909); the subspecies P. agassizi agassizi Verrill, 1880 is known from south of Newfoundland to the Caribbean and the Gulf of Mexico, as well as the Cape Verde Archipelago, Ascension Island and South Africa (A.M. Clark & Downey 1992).
Depth: 969– 4,252 m (Dilman 2008); AZO: 1,165 –2,178 m (Koehler 1909).
Habitat: soft substrates, ooze to muddy sand and rock (Perrier 1894, Koehler 1909).
Remarks: through the historical literature, several Plutonaster species were described from the Azores, including two species by Sladen (1889) based on specimens collected by H.M.S. Challenger in the Azores: P. notatus (sta 73: 38°30’N, 31°14’W, 1,829 m) and P. abbreviatus (sta 78: 37°24’N, 25°13’W, 1,829 m). Perrier (1891, 1896a) described P. granulosus based on the material collected by Hirondelle in the same area. The forms P. inermis and P. rigidus were also recorded from the Azorean waters respectively by Perrier (1896a) and Koehler (1909, 1921a). A.M. Clark & Downey (1992) concluded that all the above were conspecific and included all Azorean records in the subspecies P. agassizi notatus.