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Actinopora d'Orbigny, 1853

D'Orbigny's figure of Actinopora irregularis Scanning electron micrograph of Actinopora regularis Scanning electron micrograph of Actinopora regularis

Type species

Actinopora regularis d'Orbigny, 1853, p. 763
Cretaceous, Neocomian, Ste Croix, France

Type material: MNHN R61569, ex d'Orbigny Collection 5189 bis

Diagnostic features

  • colony encrusting, discoidal with peripheral growing edge, unilamellar, simple (not compound)

  • autozooids forming radial fascicles resembling septa on the colony surface; fascicles characterized by biserial or triserial arrangements of autozooidal apertures, new fascicles becoming intercalated between existing fascicles during growth.

  • gonozooid not identifiable in the type specimen which is poorly preserved.


Order Cyclostomata
Suborder Tubuliporina
?Family Plagioeciidae


Gregory (1909, p.5) selected Actinopora regularis d'Orbigny, 1853 as the type species of Actinopora, regarding this species as a subjective junior synonym of Ceriopora stellata Koch & Dunker, 1837. This supposed synonymy has been supported by other bryozoologists, notably Hillmer (1968, p. 84). Walter (1986) made the suggestion that A. regularis was a synonym of another d'Orbigny species - Multitubigera campicheana - which has large compound colonies. Nevertheless, Actinopora remains a frequently used genus for Cretaceous-Recent tubuliporine cyclostomes having discoidal colonies with autozooids arranged in ridge-like radial fascicles.


Gregory, J.W. 1909. Catalogue of the Fossil Bryozoa in the Department of Geology, British Museum (Natural History). The Cretaceous Bryozoa. Volume 2. BM (NH), London, 346 pp.

Hillmer, G. 1971. Bryozoen (Cyclostomata) aus dem Unter-Hauterive von Nordwestdeutschland. Mitteilungen aus dem Geologisch-Paläontologischen Institut der Universität Hamburg, 40: 5-106.

Orbigny, A. d' 1851-1854. Paléontologie Française, Terrains Crétacé, 5, Bryozoaires. Masson, Paris, 1192 pp, pls 600-800.

Walter, B. 1986. Les bryozoaires fasciculés Neocomiens. Palaeontographica Abteilungen A, 195: 75-99.