Steginoporella magnilabris (Busk, 1854)

Judith L Winston, 2016, Bryozoa of Floridan Oculina reefs, Zootaxa 4071 (1), pp. 1-81 : 8-10

Steginoporella magnilabris (Busk, 1854)

( Fig. 2 ; Table 1 )

Membranipora magnilabris Busk, 1852 : vi, pl. 65, fig. 4; 1854: 62 (part), 113.

Steginoporella elegans: Smitt, 1873: 15 , pl. 4, figs 96–101; Verrill 1900: 594.

Steganoporella magnilabris: Harmer 1900: 279 , figs 10, 31; Osburn 1914: 196; 1940: 375; 1947: 18; Canu & Bassler 1923: 63, pl. 14, figs 12, 13; 1928a: 64, pl. 7, figs 8–10, pl. 32, fig. 6; Marcus 1955: 284, pl. 2, fig. 25; Cook 1964: 53, pl. 1, fig. 4, fig. 2; 1968: 153; 1985: 108, pl. 12 D; Long & Rucker 1970: 19, figs 2, 6; Powell 1971: 769.

Steginoporella magnilabris: Shier 1964: 618 ; Pouyet & David 1979: 784, text-fig. 2, pl. 1, figs 6–7; Winston 1984: 10, fig. 18; 2005: 29, figs 73, 75; Souza 1989: 497; Vieira et al. 2008: 20; Winston & Woollacott 2009: 252, fig. 11.

Material examined. VMNH no. 70599.

Description. Colony encrusting to foliaceous; fragment found in this study was part of erect colony that had changed growth direction ( Fig. 2 A, C). Zooids typically dimorphic, all elongate, subrectangular proximally and rounded distally, but comprising only the smaller A-zooids in sole fragment found (the less-abundant larger Bzooids known to occur between them in other material). A-zooid orifice semicircular with smoothly calcified distal rim and shelf, and two condyles. B-zooid morphology similar, but opercular region enlarged, with deeper, lunate shelf. Sunken cryptocystal shelf in proximal half of all zooids, less granular than rim and with a few small pores, forming projection that covers polypide tube; with elongate opesiular grooves on either side to allow insertion of retractor muscles. Oculina specimen shown here was skeletal, but when alive both A and B zooids had strongly reinforced opercula edged with acute chitinous teeth. No avicularia. Brooding internal.

Remarks. On the basis of their unique reproductive and morphological characters, Ostrovsky (2013) created a new suborder and new superfamily Thalamoporelloidea to include the families Thalamoporellidae and Steginoporellidae . His revised classification is followed here.

Distribution. Western Atlantic: Florida, Gulf of Mexico and Caribbean. Brazil: Abrolhos Island, Bahia, Espírito Santo and Rio de Janeiro; reported to have a broader subtropical-tropical distribution (Harmer 1900).

Figures

FIGURE 2. Steginoporella magnilabris (Busk, 1854): A, colony fragment with bidirectional growth; B, another view showing very irregular zooid shapes in zone where growth changed direction; C, group of zooids. Scale bars: A, C, 1 mm; B, 0.5 mm.

Tables

TABLE 1. Measurements in mm of Steginoporella magnilabris (Busk, 1854) (colony fragment with only A zooids.

	Lz	Wz	Lo	Wo
N	6	6	6	6
Mean	0.933	0.573	0.471	0.384
SD	0.062	0.046	0.033	0.052
Min	0.864	0.540	0.432	0.306
Max	1.026	0.648	0.522	0.450