Scorpiodinipora costulata

Scorpiodinipora costulata (Canu & Bassler, 1929)

(Figs 13E, F; 20A, E)

Schizoporella costulata Canu & Bassler, 1929, p. 317 (part), pl. 36, fig. 10; not pl. 36, fig. 11.

Scorpiodinipora costulata: Harmelin et al. 2012, p. 127, figs 1–5, and synonyms therein; Taylor & Tan, 2015, p. 29, fig. 15G–I.

Material examined. VNMN-0253 (CT-18), VNMN-0254 (CT-19), VNMN-0255 (CT-23), on SEM stubs. Measurements. AzL, 0.36–0.51 (0.423 ± 0.035); AzW, 0.23–0.37 (0.270 ± 0.043); OrL, 0.12–0.15 (0.139 ±

0.008); OrW, 0.09–0.11 (0.095 ± 0.007) (n = 15, 1). Description. Colony unilaminar, encrusting, sheet-like.

Zooids small, oval in outline, distinct, delineated by groove. Frontal shield imperforate, with short costate ridges around periphery; with small, circular marginal pores between bases of ridges. Orifice subterminal, elongate, equally rounded proximally and distally, separated into anter and poster by pair of rounded condyles near middle; orifice surrounded by distinct, raised orificial rim.

Oral spines, avicularia, and ooecia lacking.

One ancestrula observed; similar in morphology to later zooids, but smaller, with proportionally smaller orifice; budding pattern affected by local impediment, unclear.

Remarks. Harmelin et al. (2012) redescribed S. costulata, clarified synonyms, and revised the known global distribution. They treated this species as a case study relevant to a number of other species (e.g., Antropora minor above) having global distributions encompassing allopatric populations showing minor morphological differences from one another, raising the question whether these broad distributions reflect broadly distributed species complexes, or are the result of anthropogenic dispersal from a native source locality via floating debris or ships, or a combination of both.

Distribution. Circumtropical in distribution; reported from the southwestern Atlantic, Caribbean Sea, eastern Atlantic, Indian Ocean, Red Sea, southeastern Mediterranean Sea, and western Pacific (Harmelin et al. 2012, and citations therein). In the Pacific, known from the Philippines (Canu & Bassler 1929), Malaysia (Taylor & Tan 2015), and Vietnam (this study).