Peniagone diaphana

Peniagone diaphana (Théel, 1882) Reports for the Azores:

Scotoanassa translucida $ Hérouard, 1899: 171–172, fig. 3, 1902: 43–45, pl. 3, figs. 4–6, pl. 6, figs. 17–20; Perrier 1902: 276; Mortensen 1927a: 368, figs. 217.2, 218.2–3.

Type locality: Great Australian Bight, Pacific (42°42’S, 134°10’E).

See: Théel (1882: 55–56, pl. 9, figs. 3–5, pl. 35, fig. 18, pl. 44, fig. 9, as Scotoanassa diaphana); Hansen (1975: 153–155, fig. 71, pl. 10, figs. 7–8); Gebruk et al. (1997: 155–156, figs. 1, A–D).

Occurrence: cosmopolitan, in the Atlantic, Pacific and Antarctic Oceans (Hansen 1975); recorded from several isolated localities throughout the Atlantic, including the Charlie-Gibbs Fracture Zone (Mid-Atlantic Ridge; Gebruk 2008), Rockall Trough, Porcupine Abyssal Plain (Gage et al. 1985), Bay of Biscay (Hérouard 1923), Gulf of Guinea (Hansen 1975), Angola Basin (Bohn 2006) and the Azores (Hérouard 1902).

Depth: 1,520 –5,600 m (Hansen 1975); AZO: 5,005 m (Hérouard 1902).

Habitat: benthopelagic (preferential swimmer; Gebruk et al. 1997); on soft sediments (mud; Hansen 1975).

Larval stage: lecithotrophic (Tyler et al. (1985a).

Remarks: Hérouard (1899, 1902) described Scotoanassa translucida, based on specimens collected by Princesse Alice between the Azores and the European continent, at a station located in the easternmost waters of the archipelago (sta 749: 39°54’00”N, 21°06’45”W, 5,005 m). Later, Hansen (1975) established the synonymy of Hérouard’s species with the Pacific P. diaphana (Théel, 1882). This species is a benthopelagic animal that spends a considerable amount of time in the water column (Miller & Pawson 1990). Gebruk et al. (1997) described juveniles taken about 10 to 200 m above the seabed, at a depth from 4,031 to 4,565 m. The great difficulty of sampling benthopelagic holothurians at great depths could be the reason for its somewhat sparse distribution in the Atlantic, particularly in the Azores, where only a single tow from about 5,000 m depth delivered specimens of P. diaphana.