Litophyton spinulosum sp. nov.

(Figs. 13f, 26-30)

Material examined. Holotype NTM C215, Queensland, Milln reef, 2 December 1976, coll. P. Alderslade ; paratypes: NTM C194-NTM C195, same data as holotype; NTM C204-NTMC214, same data as holotype; NTM C369, Bommie, Milln reef, Queensland, depth 6-10 m, February 1978, coll. D. Schubot; NTM C447, Bommie, Milln reef, Queensland, depth 6-8 m, February 1978, coll. D. Schubot; NTM C541-NTM C544, March 1978, coll. D. Schubot; NTM C761, March 1978, coll. D. Schubot; NTM C1369, Sweet-lip reef, Swain reefs, Queensland, 15 November 1980, coll. P. Alderslade; NTM C2239-NTM C02240, Bommie, Briggs reef, Queensland; depth 6-7 m, March 1978, coll. P. Alderslade; NTM C2291, Queensland, Moore reef, March 1978, coll. P. Alderslade; NTM C2841, coll. Z. Dinesen.

Description. The holotype NTM C215 is 4.3 cm high and 7 cm wide, the stalk is 1.8 cm high (Fig. 26a). The polyps are up to 0.7 mm wide and 0.5 mm high, and grouped in spherical catkins.

Polyps. With irregular arrangement of sclerites in eight points (Fig. 13f). Abaxial and lateral point sclerites are spindles with simple tubercles and spiny distal part, largest present abaxially, up to 0.45 mm long (Fig. 26d), towards the adaxial points they become smaller (Fig. 26e). Tentacles with curved scales up to 0.10 mm long (Fig. 26f). Adaxial side of the polyp stalk with many straight rods, up to 0.10 mm long (Fig. 26g). Supporting bundle composed of one or two spindles up to 1.60 mm long, with simple tubercles and sometimes a spiny tip projecting for a maximum distance of 0.30 mm (Fig. 26h). Many polyp sclerites have an optically black inner core.

Surface layer top stalk. Capstans and derivatives of capstans up to 0.10 mm long, and many spindles and unilaterally spinose spindles, up to 1.10 mm long, with simple and complex tubercles (Fig. 26i, 27 a-b).

Surface layer base stalk. Capstans, derivatives of capstans, spindles, and unilaterally spinose spindles, all with simple and complex tubercles (Fig. 27 c-d). The spindles are up to 0.30 mm long.

Interior stalk. Mostly unbranched spindles, branched spindles, and spindles with a few side branches (Fig. 27 e-f), all with simple and complex tubercles (Fig. 27g) and pointed ends. The spindles are up to 0.85 mm long.

Etymology. The Latin spinulosum, spiny, referring to the spiny colony shape, the most spiny appearance of all Australian Litophyton species.

Distribution. Great Barrier Reef: Milln reef, Moore reef, Elford reef.

Remarks. The microscope slide of NTM C204 showed somewhat bigger internal spindles, up to 1.50 mm long, NTM C541 even has spindles up to 2.00 mm long. NTM C541-NTM C544, and NTM C1369 contain xeniid type sclerites in the polyps (Fig. 28e). NTM C2291 (Fig. 26c) sclerites are also presented (Figs. 29-30). NTM C1369, NTM C2239, and NTM C2240 show smaller catkins.

This is the most common species with projecting supporting bundle on the Great Barrier Reef. L. elfordensis sp. nov. has interior stalk spindles with side branches in common with L. spinulosum sp. nov. It differs from L. spinulosum in having much longer interior stalk spindles, up to 2 mm long, and point spindles with leafy distal end.