Cranosina coronata (Hincks, 1881)

(Fig. 4A, B)

Membranipora coronata Hincks, 1881, p. 147, pl. 10, fig. 1.

Setosellina coronata: Harmer 1926, p. 265, pl. 16, figs 2 – 4.

Cranosina coronata: Tilbrook 2006, p. 25, pl. 2e; Taylor & Tan 2015, p. 12, fig. 6; Dick & Grischenko 2017, p. 63, fig. 6e, f. For other synonyms and records, see Harmer (1926) and Tilbrook (2006).

Material examined. VNMN-0215 (CT-5), on SEM stub; VNMN-0216, four colony fragments.

Measurements. AzL, 0.49–0.65 (0.573 ± 0.048); AzW, 0.32–0.50 (0.409 ± 0.047); OpL, 0.19–0.48 (0.391 ± 0.071); OpW, 0.15–0.27 (0.212 ± 0.033); AvRL, 0.08–0.22 (0.178 ± 0.036); AvRW, 0.09–0.18 (0.122 ± 0.028) (n = 15, 1).

Description. Colony unilaminar, encrusting, sheet-like.

Zooids distinct, delineated by deep groove; often widest at, or proximal to, middle. Cryptocyst extensive, comprising wide, rounded mural rim, granulated on sides and top, with coarse ridges perpendicular to opesia on inside of mural rim; mural rim smooth laterally and distally in opercular region. Opesia extensive, often irregular in outline.

Avicularium distal to each zooid, distal end of rostrum forming semi-cylindrical channel to house setose mandible, directed laterally or slightly distolaterally. Spines lacking.

Ooecia lacking; zooids use internal sac for brooding.

Distribution. This species is broadly distributed in the Indo-West Pacific region, occurring from East Africa and the Red Sea to Indonesia, the Great Barrier Reef, New Guinea, Singapore, Malaysia, Vanuatu, the Solomon Islands, Vietnam, the Philippines, and Japan (Chimonides & Cook 1994; Tilbrook et al. 2001; Tilbrook 2006; Taylor & Tan 2015; Dick & Grischenko 2017; this study).