Psolidium incubans Ekman 1925

Psolidium incubans Ekman, 1925

Figures 1f; 4f

Psolidium incubans Ekman, 1925: 5, 113–116, text fig.

27.— Arnaud, 1974: 584. — Gutt, 1988: 73.

Material examined. South Georgia, Discovery stn MS67, E Cumberland Bay, 38 m, 28 Feb 1926, BM(NH) 2008.3190 (1 specimen).

Diagnosis. Psolidium species up to 12 mm long; wrinkled body surface, created by high cups; dorsal and lateral scales not conspicuous; dorsal and lateral tube feet conspicuous.

Sole: outer peripheral single series of smaller tube feet; inner peripheral single to zig-zag to double series of larger tube feet; lacking mid-ventral (sole) radial series of tube feet; sole soft, with folds for brood-protection.

Dorsal ossicles: perforated plates with anastomosing secondary developments and multi-layering (scales), up to 700 μ m long, 0–2 tube foot canals per scale; shallow cups with 2 large central and 2 smaller end perforations, marginal knobs, cups 90 μ m long; deep goblet-like cups closed across rim, vertical blunt spines above rim, cups 70–90 μ m wide, 80–110 μ m high.

Sole ossicles: shallow cupped crosses, shallow cups with small marginal knobs, cups 80 μ m long; shallow concave perforated plates, upturned marginal knobs, up to 14 perforations, plates up to 150 μ m long.

Distribution. South Georgia, Cumberland Bay; 12– 38 m.

Remarks. As noted by Ekman (1925) this small species of Psolidium brood-protects in folds of the sole.