Beania cookae Tilbrook, Hayward, and Gordon, 2001

Dick, Matthew H. & Grischenko, Andrei V., 2016, Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan, Journal of Natural History 51 (3 - 4), pp. 141-266 : 164-166

Beania cookae Tilbrook, Hayward, and Gordon, 2001

( Figure 7 (a, b))

Beania cookae Tilbrook, Hayward, and Gordon, 2001, p. 48 , fig. 5(e, g).

Beania klugei: Hayward and Ryland 1995, p. 542 , fig. 6(a).

Material examined

NSMT-Te 1068 ( MIN- 28), dried, on SEM stub.

Measurements

AzL, 0.80–1.20 (0.939 ± 0.087) (n = 6, 1). AzW, 0.20–0.21 (0.205 ± 0.005) (n = 4, 1). AvL, 0.114 –0.119 (0.117 ± 0.003), AvD, 0.064 –0.069 (0.067 ± 0.003) (n = 3, 1). Average AvL/ AvD ratio, 1.7 (n = 3, 1).

Description

One colony observed; tiny (~15 zooids), recumbent, loosely attached parallel to substratum by basal radicles, frontal side of zooids facing up; colony off- white, tinged slightly with orange. Zooids ( Figure 7 (a)) bud single daughter zooid basodistally, and one from proximolateral wall on each side. Zooids elongate, with squared distal corners; tapering in proximal one-quarter to narrow cylinder at point of origin. Frontal wall entirely membranous; other walls weakly calcified. Each distolateral corner bears small, non-articulated spinous process; no articulated spines observed, but one zooid shows minute spine scar on lateral margin between avicularium attachment and distal process. Avicularia ( Figure 7 (b)) paired, one attached by short peduncle on each lateral margin at level of base of operculum; chamber somewhat bulbous; rostrum hooked at end; mandible long-triangular, occupying about half the length of membranous rostral area. Avicularium length to depth ratio about 1.7. No ovicells or ancestrula in our specimen.

Remarks

Tilbrook et al. (2001) discussed the differences between Bugula cookae and the similar species B. klugei Cook, 1968 . We identified our specimen as the former based on the domed shape of the avicularia. Mean zooid length is smaller (0.94 mm) than in the holotype (1.23 mm) from Vanuatu ( Tilbrook et al. 2001), although this difference may be due to our small colony consisting partly of zooids in the zone of astogenetic change .

Occurrence

We found a single small colony at the MIN site. This species appears to be restricted to the subtropical and tropical western Pacific, previously reported from Vanuatu and (as B. klugei ) and from the Great Barrier Reef ( Hayward and Ryland 1995).