Hemigellius pilosus

Species Hemigellius pilosus (Kirkpatrick, 1907)

(Figure 3)

Synonomy: Gellius pilosus Kirkpatrick, 1907; Haliclona (Gellius) pilosa (Kirkpatrick, 1907); Haliclona pilosa (Kirkpatrick, 1907).

Specimens. BELUM. Mc 2015.608 Grotto Island, Verdansky Base (Site 1) (65°14.615’S, 64° 15.019’W), depth 14– 24 m; collected by C. Goodwin and E. Priestley, 16/02/2015; BELUM. Mc 2015.700 Vieugue Island (65°38.758’S, 65° 12.540’W), depth 10–22 m; collected by C. Goodwin and E. Priestley, 23/02/2015. BELUM. Mc 2015.784 Under Spiggot Peak, Orne Harbour (64°37.755’S, 62° 33.018’W), depth 5–21 m; collected by C. Goodwin and E. Priestley, 25/02/2015.

Comparative material examined. Gellius pilosus Kirkpatrick, 1908 Holotype. BMNH 1908.2.5.195f (spicule preparation); BMNH 1908.2.5.195k (tissue section).

External morphology. In situ appearance (Figure 3A, B): Beige branched sponge with flattened branches. The largest of our three specimens was over 30 cm in height and the smallest was around 10 cm. Branches are 0.5–1.5 cm maximum diameter. The branching pattern is irregular with some branches dividing into two and others several fingers which may be webbed together. Often the branches are rounded at their tips but some are pointed—this seems to be when new divisions are starting off.

Preserved appearance. Soft grey branched sponge with softly hispid surface. Ends of skeletal fibres project about 0.5–1 mm beyond the ectosome.

Skeleton (Figure 3C): Columns of 3–4 oxea joined by single spicules. Fanning slightly at surface. Projecting ends of columns form surface hispidation.

Spicules: Oxeas (Figure 3D): BELUM.Mc2015.608 491(523)566 by 24(28) 34 µm; BELUM.Mc2015.784 Oxeas 368(409)439 by 14(19) 23 µm

Sigmas (Figure 3E): BELUM.Mc2015.608 27(32) 39 µm; BELUM.Mc2015.784 20(32) 48 µm

Remarks. Kirkpatrick (1907, 1908) described this species as an ‘erect flattened triangular or elongate lamella divided or digitate at the upper edges’ with a ‘finely conulose and pilose’ surface. The skeleton consists of primary fibres 2–5 spicules thick joined by secondary fibres usually one but sometimes two or three thick. The oxea are 537 by 23 µm and sigmas 39 µm in length and 16 µm in breadth (our measurements from the holotype: styles 550(562)640 by 20(27) 35 µm, sigmas 30(36) 40 µm. The spicule dimensions and form, skeletal form and external form of our specimens are a good match for the type specimen although the oxea in BELUM.Mc2015.784 are slightly shorter. Hajdu et al. (2016) recently reported a specimen from 40 m in the South Shetland Islands. Their figured specimen has a slightly different form to ours with more elongate branches and is reported as being dark yellow to orange in colour.

Distribution. This species was originally described from the Ross Sea in 46–55 m and has since been reported from the South Shetland Islands in 40 m (Hajdu et al. 2016), Ross Sea (Brueggeman (1998); Ocean Survey 20/20 (2013); Mangano et al. (2014)) and the South Pacific (NIWA 2016). Burton (1929) considered H. pilosus a synonym of Haliclona (Gellius) rudis (Topsent 1901), however, he later revised this (Burton 1932).