The revision of the types and “topotypes” of Hadrophyllum orbignyi Milne-Edwards & Haime, 1850 brings new data on this species and on the genus Hadrophyllum. The type species, H. orbignyi, is known from the Eifelian (costatus costatus-kockelianus conodonts zones) of Eastern Americas Realm. A lectotype is selected in the original material. A detailed study of the morphology shows important variations concerning the shape of the corallum, the length of the cardinal septum, the structure of the counter-counter lateral area; two new structures are defined, the interseptal ridges and the fossuloïds. The septal apparatus consists of costosepta, it is why the “epitheca” is lacking. The corallum is massive, no dissepiments nor tabulae, and the wall is septothecal. The fibrous nature of the septa is pointed out. The polyp enclosed widely the corallum; H. orbignyi was capable of automobility. The synonymy of the genus is reviewed; only two species can be referred to it, the type species and H. asturicum. The systematics of the “Hadrophyllidae” is revised, especially the Weyer’s one (1975) and two new sub-families, the Hadrophyllinae n. status and the Microcyclinae n. subfam., are erected.
Coelenterata, Rugosa, Hadrophyllum, Devonian, North America, morphology, microstructure, systematics