Trimuricea omanensis n. sp.

(Figs. 13 c, 19–20, 32a)

Material: Holotype, RMNH Coel. 41599, Oman, Strait of Hormuz, Musandam, no palm beach (OM11 A7 S6), 26.37336° N 56.535694° E, 10–25 m depth, coll. K. Samimi-Namin, 9 May 2011.

Description. The holotype is a piece of colony, about 35 cm high and 14 cm wide, that is branched in one plane and has many anastomoses forming a network (Fig. 13 c). The calyces are dome shaped, closely set to each other and situated all around the branches. They are low, only 1–2 mm in height and have a diameter of up to 1 mm.

The points have triradiates (Fig. 19 a), along with curved, hockeystick or boot-shaped sclerites, or spindles (Fig. 19 b), 0.15–0.25 mm long. The upper ray of the triradiates and upper part of the spindles is echinulate or smooth for up to 0.12 mm, and slightly blunt. The collaret spindles are 0.20–0.35 mm long (Fig. 19 c); the middle part of the convex side is more tuberculated than the concave side and both the ends. The concave side is relatively smooth in the center with more tuberculation at both ends. These polyp sclerites have few tubercles. A few tentacle scales are present, up to 0.08 mm long (Fig. 19 d).

The calyces have thornscales, 0.10–0.25 mm long, with a warty base, and one or more echinulate or smooth thorns up to 0.10 mm long (Figs. 19 e, 20a).

The coenenchyme has simple spindles, 0.10–0.30 mm long, with simple and complex tubercles (Fig. 20 b). Additionally, spindles with one smooth, thorn-like end are also present (Fig. 20 c). Also a few sclerites are present that superficially resemble unilateral spinose spindles.

Colour. The live colony was yellow with magenta extended polyps (Fig. 32 a). Preserved colony is brown. All sclerites are colourless.

Etymology. The species is named after the country Oman where the holotype was found.

Remarks. The species mostly resembles Trimuricea inermis, both species having small coenenchymal spindles and calicular thornscales. But it differs in having some sclerites resembling unilateral spinous spindles, some spindles with one thorny end and branch anastomoses forming a net-like colony shape.