Hamaraxonia, a new pseudocolumellate genus of Middle Devonian deep-water Rugosa (Anthozoa) from Morocco
The monotypic genus Hamaraxonia gen. nov., with type species Hamaraxonia africana sp. nov., is described, based on only four specimens, from the middle Eifelian (top Costapolygnathus costatus Zone to basal Tortodus australis Zone) of the Hamar Laghdad, Anti-Atlas, SE-Morocco. In its prominent axial boss and dissepiments in maturity, the new genus is unique among pre-Carboniferous ahermatypic Rugosa. It is classified within the still polyphyletic subfamily Columnaxoninae Weyer, 1980 of the family Cyathaxoniidae Milne-Edwards & Haime, 1850 (suborder Cyathaxoniina Spasskiy, 1977). Possible ancestors will probably be found among the neighbouring subfamily Laccophyllinae Grabau, 1928. For the moment, a phylogenetic line: Laccophyllum Simpson, 1900 → Hamarophyllum Berkowski, 2004 → gen. nov. pro Cyathaxonia hercynica Roemer, 1855 (Weyer & Zagora, 1990) → Hamaraxonia gen. nov. may be proposed, pending further records from other regions and additional intermediate taxa. The commonly used term columella (aseptal origin) and the nearly forgotten term pseudocolumella (septal origin) are redefined in the already morphogenetic sense of their authors (Milne-Edwards & Haime 1848) by selecting morpho-terminological types: Cyathaxonia cornu Michelin, 1847 (late Tournaisian), and Clisiophyllum keyserlingi M'Coy, 1849 (middle/late Visean).