Plesiocleidochasma cleidostomum (Smitt, 1873) comb. nov.

(Fig. 35; Table 34)

Lepralia cleidostoma Smitt, 1873: 62, pl. 11, figs 217–219.

Lepralia porcellana: Osburn 1914: 209.

Hippoporina cleidostoma: Canu & Bassler 1928a: 104, pl. 9, fig. 7, pl. 32, fig. 6, text-fig. 18.

Hippoporina porcellana: Osburn 1940: 428; Shier 1964: 633.

Cleidochasma porcellanum: Cheetham & Sandberg 1964: 1032, text-fig. 35; Long & Rucker 1970: 19, fig. 4.2; Winston 1982: 147, fig. 80.

Schedocleidochasma porcellanum: Winston 2005: 87, figs 244–246.

Material examined. MCZ # 90, syntype of Lepralia cleidostoma, May 1, 1868, Cast No. 7, 26 fms [off Sombrero Key], L. Pourtales; VMNH no. 70652, 70653, 70654; USNM no. 1283259.

Description. Colonies encrusting, in unilaminar patches to multilaminar mounds. Primary layer of zooids regularly hexagonal; frontally budded zooids irregularly polygonal. Frontal shield smooth to sparsely granular, flat over most of frontal surface (Fig. 35 B), raised around orifice, imperforate except for a few marginal pores. Orifice cleithridiate, rounded distally with proximally directed condyles, and narrow U-shaped sinus. Single or paired adventitious avicularia may occur on umbo proximolateral to orifice; rostra and mandibles acutely triangular (Fig. 35 C). Ovicell hyperstomial, prominent and delicately striated when newly formed, becoming granular and embedded in secondary calcification with age; imperforate, with frontal area in form of a thin curved-edged plate (labellum) between two lateral slits, leaving narrowly transverse opening (Fig. 35 A, B). Embryos reddish-pink.

Discussion. Floridan Plesiocleidochasma cleidostomum is part of the ‘ Cleidochasma porcellanum ’ species complex, widely distributed in tropical and subtropical habitats, including the Western Atlantic (see Winston 2005).

Soule, Soule & Chaney (1991) and Cook & Bock (1996) revised the genera and species included in the Cleidochasmatidae. Winston (2005) placed Smitt’s species in Schedocleidochasma, but Berning (2012) recently synonymized Schedocleidochasma under Plesiocleidochasma, a decision followed here.

Distribution. Cape Hatteras to Florida, Caribbean, and Gulf of Mexico.