Bryozoa of Floridan Oculina reefs
Judith L Winston
Zootaxa
2016
4071
1
1
81
67L2X
Hincks, 1880
Hincks
1880
[151,545,1578,1604]
Gymnolaemata
Antroporidae
Antropora
Animalia
Cheilostomatida
19
20
Bryozoa
species
minor
Membrendoecium parvusCanu & Bassler, 1928a: 61, pl. 1, figs 1–2. Membrendoecium minus: Marcus 1937: 50, pl. 9, fig. 22A, B. Antropora minor: Tilbrook 1998: 34, fig. 2A–F; Vieira et al.2008: 14; Winston et al.2014: 151, fig. 7.
Material examined.VMNH no. 70609, 70610; USNM no. 1283235.
Description.Colonies encrusting, unilamellar, on calcareous substrata ( Fig. 10A). Zooids oval to subtriangular, broader proximally. Frontal membrane underlain by beaded cryptocyst and rimmed by proximally elongated gymnocyst ( Fig. 10B). Cryptocystal shelf also broader proximally, gradually narrowing to distal wall around half-moon shaped operculum and forming oval to bell-shaped opesia. Interzooidal avicularia interspersed between autozooids, each with circular foramen, granular cryptocyst and well-developed gymnocyst that may have a small tubercle ( Fig. 10B, C); mandible U-shaped, rostral rim well calcified. Brooding zooids show thickened lunate rim of calcification distally. TABLE 9.Measurements in mm of Antropora minor(Hincks, 1880). Lz Wz Lo Wo Lcircz Wcircz N 18 18 18 18 18 18 Mean 0.381 0.251 0.041 0.061 0.257 0.211 SD 0.040 0.024 0.007 0.008 0.037 0.025 Min 0.324 0.216 0.036 0.054 0.216 0.162 Max 0.450 0.306 0.054 0.072 0.324 0.252 `Remarks. The most unusual feature of this species is its ability to calcify over the frontal membrane and opesia of many zooids in a colony ( Fig. 10E, F). In some zooids a small central opening may remain. In others the entire frontal surface is covered by concentric rings of calcification. These ‘closure plates’ may be a way to protect zooids from predation (colonies on Oculinashowed a considerable amount of damage and repair), or a means to preserve nutritive resources in a food-scarce habitat.
Distribution. Oculinabanks, Atlantic coast of Florida, Brazil.