Hygrosoma petersii (A. Agassiz, 1880)

Fig. 19 A–C.

Phormosoma petersii: A. Agassiz, 1879: 76 .

Hygrosoma petersi: Clark & Courtman-Stock, 1976: 220 .

Hygrosoma petersii: Mortensen, 1935: 202 –208. Pls. XIII–XVII. Pl. XVIII, Fig. 2. Pl. XIX, Fig. 2. Pl. LXXVIII, Figs I, 3–5, 24, 25; Schultz, 2011: 1099, Figs 1923–1924.

Echinosoma petersii: H.L. Clark, 1925a: 56 .

Material examined. A9812-079-DT; A22124; A22219; A22248; A22251.

Identification. Preserved test collapsed, with circular outline. Large oral tubercles with distinctive areoles, disappearing towards peristome. Pore-pairs in single series. Preserved test purple.

Global maximum size. Maximum test diameter 180 mm.

Global distribution. Widely distributed in North Atlantic from off South-West Ireland to Azores and Senegal and from off New Jersey, USA to West Indies, also reported from West coast of South Africa; at 200–3200 m depth range (Schultz 2011).

Remarks. Clark & Courtman-Stock (1976) have flagged Clark’s (1923 & 1924) East coast record of the species as they point out it “is queried by Mortensen as unlikely to refer to this Atlantic species; at least one locality off Natal is duplicated by the British Museum specimen which proved to be referable to Sperosoma biseriatum ”. Differs from Araeosoma paucispinum in arrangement of pore-pairs, where Hygrosoma petersii has pore-pairs in a single series and A. paucispinum in oblique arcs forming three ventral series.