Plesiocleidochasma cleidostomum (Smitt, 1873) Smitt, 1873

Judith L Winston, 2016, Bryozoa of Floridan Oculina reefs, Zootaxa 4071 (1), pp. 1-81 : 63

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.

Figures

FIGURE 35. Plesiocleidochasma cleidostomum (Smitt, 1873): A, group of zooids; B, close up of orifice and ooecium; C, orifice and frontal avicularium; D, another orifice. Scale bars: A, 0.5 mm; B, D, 0.1 mm; C, 0.2 mm.

Tables

TABLE 34. Measurements in mm of Plesiocleidochasma cleidostomum (Smitt, 1873).

	Lz	Wz	Lo	Wo	Lov	Wov	Lav	Wav
N	18	18	18	18	12	12	1	1
Mean	0.428	0.321	0.124	0.095	0.182	0.240	0.126	0.054
SD	0.043	0.031	0.009	0.011	0.021	0.019	------	------
Min	0.360	0.288	0.108	0.081	0.144	0.148	0.126	0.054
Max	0.522	0.396	0.144	0.126	0.216	0.270	0.126	0.054