Trimuricea spinosa n. sp.

(Figs. 21 b, 26–27)

Trimuricea sp. Samimi-Namin & van Ofwegen, 2009b.

Material: Holotype, RMNH Coel. 39317, one colony, Persian Gulf, Larak Island, 26° 53ʹ 15″ N, 56° 23′ 36″ E, 14–16 m depth, coll. K. Samimi-Namin, 5 December 2007.

Description. The holotype is about 8 cm high and 8.5 cm wide, branched in one plane, and has anastomoses forming a network (Fig. 21 b). The stem is 1.5 cm long and 0.5 cm thick and all branches are 3–4 mm thick. Some branches have lost the tissue and are covered by algae. The calyces are dome shaped, closely set to each other and situated all around the branches. They are up to 0.5 mm high and 1 mm wide.

The points have triradiates (Fig. 26 a) along with, hockeystick or boot-shaped sclerites, or spindles that can be curved or sinuous (Fig. 26 b), 0.10–0.40 mm long. The upper ray of the triradiates and upper part of the accessory sclerites is strongly echinulate or tuberculate for up to 0.18 mm. The collaret spindles are 0.20–0.44 mm long (Fig. 26 c); and the middle part of the convex side is slightly more tuberculate than the concave side and both the ends. The concave side is relatively smooth with very few tubercles. There are a few tentacle scales present, up to 0.05 mm long (Fig. 26 d).

The calyces have thornscales, 0.15–0.47 mm long, with a warty base, and one or more, smooth or echinulate thorns up to 0.23 mm long (Fig. 27 a).

The coenenchyme has spindles, 0.30–0.68 mm long, with simple and complex tubercles (Fig. 27 b) along with a few crosses and irregularly branched forms (Fig. 27 c).

Colour. The live colony was white-yellowish, with magenta polyps. Preserved it is brown. All sclerites are colourless (For in situ photo refer to Samimi-Namin & van Ofwegen 2009b).

Etymology. The specific epithet is derived from the Latin spinosus (thorny). It refers to the thornscales with several thorns.

Remarks. This species mostly resembles T. flava n. sp., but differs in having colourless sclerites and triradiates with a strongly echinulate upper part. Moreover, the collaret spindles of T. spinosa are far less tuberculate.