You are here
Bryozoa
Amphiblestrum solidum (Packard, 1863)
SUMMARY
Colonies are multiserial, forming encrusting sheets. The ancestrula is ovoidal, about 0.23 mm long by 0.15 mm wide, with a shelf-like proximal cryptocyst and a semielliptical opesia that is slightly longer than wide. Three zooids are budded directly from the ancestrula, one distally and two distolaterally.
Autozooids are elongated and rounded rhomboidal in outline shape. In Coralline Crag material they average about 0.50 mm long by 0.38 mm wide. A cryptocystal frontal wall occupies about half of the frontal surface and is slightly depressed and granular; no gymnocyst is visible in astogenetically mature zooids. The opesia is large and trifoliate, with a straight or slightly arched proximal edge and a pair of lateral indentations located mid-length. Oral spine bases are present at the two distolateral corners of the opesia. Closure plates occlude the opesia in some zooids, especially from early astogeny and usually contain a small ovoidal opening. Ovicells are abundant, globular, with a large, arch-shaped proximal window in the ectooecium exposing the granular entooecium.
Avicularia are abundant and interzooidal, scattered somewhat irregularly between the autozooids and in most cases proximally directed. They have an extensive gymnocyst and an acute triangular rostrum inclined at an angle to the colony surface. Ovicellate and non-ovicellate zooids do not differ in their associated avicularia.