Briareum cylindrum, Samimi-Namin, Kaveh & van Ofwegen, Leen P., 2016

Samimi-Namin, Kaveh & van Ofwegen, Leen P., 2016, Overview of the genus Briareum (Cnidaria, Octocorallia, Briareidae) in the Indo-Pacific, with the description of a new species, ZooKeys 557, pp. 1-44 : 5-7

Taxon classification Animalia Alcyonacea Briareidae

Briareum cylindrum sp. n. Figures 2 A–D, 3, 4, 5, 6, 7

Material examined.

Holotype: RMNH Coel. 34193, Malaysia, northwest of channel running due west out of SMART resort, about 100 m away, lobster wall, depth 11 m, 8 July 2004, coll. Nicolas J. Pilcher (0PHG1352-C) (id. Briareum excavatum ).

Paratypes: RMNH Coel. 2241, Indonesia, Java, coll. C.G.C. Reinwardt (id. Briareum stechei ); RMNH Coel. 2242, 1 microscope slide, Indonesia, Java, coll. C.G.C. Reinwardt, (id. Briareum stechei ); RMNH Coel. 11655, Australia, Feather Reef, seaward slope, 17°33'S, 146°23'E, depth 0-10 m, 6 July 1975, coll. R.N. Garrett (id. Briareum stechei ); RMNH Coel. 11797, Australia, Queensland, Great Barrier Reef, Heron Island, on side of Bommie, 15 m depth, 20 July 1973, coll. N. Coleman (id. Briareum stechei ); RMNH Coel. 13747, Australia, Coral Sea, Mellish Reef, depth 8 m, encrusting on coral block, 1 May 1979, coll. N.L. Bruce, aboard R/V Lady Basten (id. Briareum stechei ); RMNH Coel. 32569, China, Hainan Island, Xidao, 50 km from Haikou City; depth 15 m. October 2003, coll. Wenhan Lin (HSD 9); RMNH Coel. 32570, China, Hainan Island, Xidao, 50 km from Haikou City; depth 15 m. October 2003, coll. Wenhan Lin (HSE 25); RMNH Coel. 41443, Buginesia Progr. UNHAS- NNM 1994/1995, SUL.BCW, Indonesia, southwest Sulawesi, Spermonde Archipelago, west of Barang Caddi (=11 km Northwest of Ujung Pandang = Makassar), 5°05'S, 119°19'E, coral reef, SCUBA diving, 4 May 1994, coll. B.W. Hoeksema; RMNH Coel. 41444, Buginesia Progr. UNHAS- NNM 1994/1995, SUL.KAPN, Indonesia, southwest Sulawesi, Spermonde Archipelago, north of Kapoposang Isl (= 66 km NW of Ujung Pandang = Makassar), 4°40'S, 118°57'E, coral reef, SCUBA diving, coll. B.W. Hoeksema; RMNH Coel. 41446, CEB.05, Philippines, Cebu Strait, west of Bohol, west side of Cabilao Island, south side fish sanctuary, 9°52.60'N 123°45.61'E, dense algae-covered reef flat to 4 m depth, vertical wall with caves to 45 m, SCUBA diving, 8 November 1999, coll. L.P. van Ofwegen; RMNH Coel. 41447, CEB.11, Philippines, Cebu Strait, west of Bohol, east side of Cabilao Island, south of Cambacis, 9°52.92'N 123°47.37'E, to 6 m patchy reef with algae, below steep slope with caves, snorkelling and SCUBA diving, 14 November 1999, coll. L.P. van Ofwegen.

Description.

The holotype consists of several fragments of an encrusting colony, the largest being 4 by 1.5 cm in diameter (Figure 2A) with white surface and magenta underside. Calyces hardly projecting.

The calyces contain colourless, flattened rods with prominent simple tubercles (Figure 3A, B). These rods are up to 0.20 mm long. The cortex contains colourless spindles, cylinders, and tripoids (Figure 3C). All these forms have complex tubercles, often arranged in girdles. These sclerites can be up to 0.60 mm long but most are only 0.30 mm long. The medulla contains magenta spindles and branched spindles with simple or complex tubercles (Figure 4). These sclerites are 0.20-0.60 mm long. They can be fused into small clumps.

Etymology.

The Latin “cylindrum”, cylinder, refers to the shape of the sclerites.

Morphological variation.

RMNH Coel. 13747, RMNH Coel. 32569, RMNH Coel. 41443 and RMNH Coel. 41444 have distinctly longer sclerites with more complex tubercles (Figs 5-7). RMNH Coel. 13747 has slightly raised calyces (Figure 2B); RMNH Coel. 32569 has distinct calyces (Figure 2C), RMNH Coel. 41443 has no calyces at all (Figure 2D).

Remarks.

Briareum cylindrum mostly resembles Briareum stechei but differs in having many cylinders with complex tubercles in the coenenchyme.

Distribution.

Australia, Coral Triangle, China. Depth 0-15 m.