Sinularia choui, Benayahu & van Ofwegen, 2011

Benayahu, Y. & van Ofwegen, L. P., 2011, New Species Of The Genus Sinularia (Octocorallia: Alcyonacea) From Singapore, With Notes On The Occurrence Of Other Species Of The Genus, Raffles Bulletin of Zoology 59 (2), pp. 117-125 : 118-122

Sinularia choui , new species

( Figs. 1 a–4)

Material examined. – Holotype ( ZRC 1999.2249 ) and four microscope slides deposited at TAU ( ZMTAU Co 35103), Terumbu Penpang Tengah, 2–4 m, coll. Y. Benayahu, 14 Jul. 1999.

Diagnosis. – The holotype is a stalked colony, with a maximum cross-section of 2 × 4 cm and 5 cm high ( Fig. 1a ). The polypary consists in densely placed lobes that bear lobules with a rounded tip. Some of the polyps are partially retracted and visible on the surface of the lobules.

The polyps have a collaret and eight points. The point sclerites have poorly developed heads, up to 0.19 mm long ( Fig. 2a ). The collaret spindles are slightly bent, 0.13–0.24 mm long, featuring sparse tubercles on their surface ( Fig. 2b ).

The surface layer of the lobules has leptoclados - type clubs, 0.10–0.26 mm long, whose heads mostly feature pointed leaf-like processes ( Fig. 2c ). In addition, there are clubs, up to 0.24 mm long, with heads featuring a prominent warty ornamentation ( Fig. 3a ), and others that are even longer, up to 0.38 mm ( Fig. 3b ). The surface of the lobes has spindles, up to 0.51 mm long, with warty tubercles that are occasionally more common at one end of the spindle than the other ( Fig. 3c ).

The clubs with leaf-like processes on the surface layer of the colony base are 0.10–0.17 mm long ( Fig. 4a ). They have wider handles and are shorter compared to those of the lobules’ surface. Some of these clubs, up to 0.30 mm long, feature heads with a warty ornamentation ( Fig.4b, c ). In addition, there are capstan-like sclerites, 0.10–0.16 mm long ( Fig. 4d ). The spindles of the surface of the base are shorter than those of the surface of the lobes, up to 0.37 mm long ( Fig. 4e ).

The interior of the lobules has spindles, up to 1.95 mm long, some bent and with a side branch ( Fig. 3d ). Most of the spindles have sparsely dispersed small tubercles ( Fig. 3e ), but a few have more densely located and larger ones ( Fig. 3f ). The spindles in the interior of the base are up 1.90 mm long ( Fig. 4f ) with a dense tubercular sculpture ( Fig. 4g ).

Colour. – The preserved holotype is light cream.

Etymology. – The species name honours Prof. L. M. Chou, National University of Singapore, a prominent coral reef scientist, in appreciation of his initiative to conduct a soft coral survey in Singapore and in recognition of his immense contribution to the study of the Singapore reefs.

Remarks. – Based on the presence of leptoclados - type clubs, collaret and point sclerites we assigned S. choui to clade 5C of McFadden et al. (2009). Within this clade, S. pumila Dautova et al., 2010 reveals two types of clubs in the surface layer of the lobes, with head either featuring pointed leaf-like processes or a warty ornamentation. In S. choui the clubs are larger than in S. pumila : the leafy ones reach up to 0.26 mm compared to 0.15 mm; the warty ones, 0.38 mm compared to 0.26 mm, respectively. Similarly, in S. choui most of the clubs of the surface layer of the base are longer than 0.10 mm ( Fig. 4a ), whereas in S. pumila they are 0.10 mm long or less ( Dautova et al. 2010: Fig. 18). Hence, we conclude that S. choui has unique sclerite features, and does not resemble any congeneric species already described.

Figures

Fig. 1. Sinularia from Singapore; a, Sinularia choui new species; holotype (ZRC 1999.2249); b, Sinularia acuta Manuputty & Ofwegen, 2007 (ZRC 1999.2268). Scale bar 10 mm.

Fig. 2. Sinularia choui new species; holotype (ZRC 1999.2249): a–b, polyp sclerites; a, point-clubs; b, collaret spindles; c, clubs of surface layer of lobules with leaf-like processes. Scale bar 0.10 mm.

Fig. 3. Sinularia choui new species; holotype (ZRC 1999.2249): a–c, sclerites of surface layer of lobules; a, clubs with head featuring warty ornamentation; c, spindles; d, spindles of interior of lobules; e–f, tubercles on spindles. Scale bar at a and c 0.10 mm; that at a only applies to a, that at c applies to b–c; scale bar at d 1 mm only applies to d.

Fig. 4. Sinularai choui new species; holotype (ZRC 1999.2249): a–e, sclerites of surface layer of colony base, a–e; a, clubs with leaflike processes; b–c, clubs with head featuring warty ornamentation; d, capstans; e, spindles; f, spindles of interior of base; g, tubercles on spindle. Scale bar at a and e 0.10 mm; that at a applies to a–d; that of e only applies to e; scale bar at f 1 mm.