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Acanthodesia delicatula (Busk, 1859)
Family: MembraniporidaeGenus: Acanthodesia
- syntype: B.M.(N.H.) Palaeont. Dept. D38153
- syntype: B.M.(N.H.) Palaeont. Dept. B1669
- syntype: B.M.(N.H.) Palaeont. Dept. D38549
- syntype: B.M.(N.H.) Palaeont. Dept. B1652
Colonies are multiserial and erect, forming large bifoliate expansions that may be folded. Early astogeny has not been described in material from the Crags.
Autozooids average about 0.50 mm long by 0.24 mm wide, and in outline shape are typically rectangular to very slightly rhomboidal (i.e. attaining a maximum width about mid-length). They are arranged in well-defined rows separated from those of adjacent rows by a narrow groove along which the colony may split. The opesia is longitudinally elliptical and occupies most of the frontal surface with the exception of the cryptocyst which forms a narrow, inwardly sloping shelf at the proximal end of the zooid. Cryptocystal calcification is granular, the granules becoming smaller and fewer towards the opesia. Short spinules are sometimes present on the proximal edge of the opesia, often accentuated by overgrowths of epitaxial cement, but there is no obvious plectriform apparatus. Gymnocyst and gymnocystal tubercles are not developed. Ovicells are lacking.
Avicularia are absent.