Litophyton acutum, Van, 2020

Van Ofwegen, Leen P., 2020, The genus Litophyton Forskål, 1775 (Octocorallia: Alcyonacea: Nephtheidae) from Australia, Zootaxa 4764 (1), pp. 1-131 : 42

Litophyton acutum sp. nov.

( Figs. 31 a-b, 32a-b, 33-35)

Material examined. Holotype NTM C4107 ; Queensland, Great Barrier Reef, Davies reef, 5-10 m depth, 15 April 1981, coll. Z. Dinesen ; paratypes: NTM C4108, Queensland, Great Barrier Reef, Rib reef, depth 10-15 m, 26 May 1981, coll. Z. Dinesen; NTM C1365, Queensland, Great Barrier Reef, Sanctuary reef, 13 November 1980; coll. P. Alderslade; NTM C3955, Queensland, Great Barrier Reef, Flinders reef, depth - 2 m; 22 November 1981, coll. Z. Dinesen; NTM C3961, Queensland, Great Barrier Reef, Dip reef, depth 1-5 m; 6 February 1981, coll. Z. Dinesen; NTM C3979, Queensland, Great Barrier Reef, Flinders reef, S.W., depth 5-10 m; 26 November 1981, coll. Z. Dinesen; NTM C3996, coll. Z. Dinesen; NTM C4028, Queensland, Great Barrier Reef, Davies reef, depth 1-5 m, 15 April 1981, coll. Z. Dinesen.

Description. The NTM C4107 holotype is 5 cm high and 10 cm wide, the stalk is 2 cm long ( Fig. 31a ). The polyps are grouped in conical catkins, they are up to 0.5 mm wide and high.

Polyps. With irregular arrangement of sclerites in points ( Fig. 32a ). Abaxial and lateral point sclerites are unilaterally spinous or foliaceous spindles, the largest present abaxially, up to 0.50 mm long, laterally they are up to 0.25 mm long ( Fig. 33a ). Adaxially there are only tentacles sclerites, small rods, up to 0.10 mm long ( Fig. 33b ). The polyp stalk next to the adaxial tentacles has a few small almost smooth rods ( Fig. 33c ). Supporting bundle not projecting, composed of spindles up to 1 mm long, with simple tubercles and a somewhat spiny distal end ( Fig. 33d ).

Surface layer top stalk. Spindles and unilaterally spinose spindles, up to 0.55 mm long, with simple and complex tubercles and long spines ( Fig. 33e ).

Surface layer base stalk. Capstans and derivatives of capstans, spindles and unilaterally spinose spindles, with simple and complex tubercles ( Fig. 33 f-g, 34a). The derivations of capstans and unilaterally spinose spindles have very large spines. The spindles are up to 0.50 mm long.

Interior stalk. Spindles, up to 1 mm long ( Fig. 34b, c ), with pointed ends and simple and complex tubercles ( Fig. 34d ). The smaller spindles are often branched.

Variability. Paratype NTM C3979 ( Fig. 31b ) overall shows more slender internal spindles ( Fig. 35k ). This is probably caused by different sampling position. Both the holotype and this paratype miss the basal part of the stalk.

Etymology. From the Latin acutus, acute, sharp, pointed, refers to the interior spindles with pointed ends.

Distribution. Queensland: Davies reef, Rib reef, Sanctuary reef, Flinders reef, Dip reef.

Remarks. The holotype obviously is lacking the very base of the stalk ( Fig. 31a ).

L. acutum sp. nov., L. obtusum sp. nov., and L. territoryensis sp. nov. all have unilaterally spinose sclerites with long spines. L. acutum and L. territoryensis with interior of the stalk with many spindles with pointed ends, but the spindles of L. territoryensis have much finer tuberculation. L. obtusum has many interior stalk spindles with blunt ends and less branched small internal stalk spindles.

Figures

FIGURE 31. Litophyton type specimens: a, L. acutum n. sp., holotype NTM C4107; b, paratype NTM C3979; c, L. obtusum n. sp., holotype NTM C4164.

FIGURE 32. Lateral views polyp armature of Litophyton species: a, L. acutum n. sp., holotype NTM C4107; b, paratype NTM C3979; c, L. obtusum n. sp., holotype NTM C4164; d. L. territoryensis n. sp., holotype NTM C3187; e, paratype NTM C11170; f, paratype NTM C5651.

FIGURE 33. Litophyton acutum n. sp., holotype NTM C4107; a, abaxial and lateral point spindles; b, tentacle rods; c, polyp stalk rod; d, supporting bundle spindle, partly; e, sclerites of surface layer top of stalk; f-g, sclerites of surface layer base of stalk. Scale at b also applies to c, f; scale at a also applies to d-e, g.

FIGURE 34. Litophyton acutum n. sp., holotype NTM C4107; a, sclerites of surface layer base of stalk; b-c, spindles of interior base of stalk; d, tuberculation of interior base stalk spindle. Scale at a also applies to c.

FIGURE 35. Litophyton acutum n. sp., paratype NTM C3979; a, abaxial point spindles; b, lateral point spindles; c-d, tentacle scales; e, supporting bundle spindles; f-g, sclerites of surface layer top of stalk; h-i, sclerites of surface layer base of stalk; j-k, spindles of interior base of stalk; l, tuberculation of interior base stalk spindle. Scale at a also applies to g, i, j, l; scale at b also applies to c, f, h.