Coloniality in the rugose coral family Geyerophyllidae MINATO 1955

The family Geyerophyllidae MINATO 1955 includes corals having clinotabulae, lonsdaleoid dissepiments and a variably complex axial structure formed as an extension of the cardinal septum. Within this family, MINATO & KATO (1975) included three genera originally considered to have a colonial (fasciculate) growth habit – Carinthiaphyllum HERITSCH 1936, Lonsdaleoides HERITSCH 1936 and Darwasophyllum PYZHYANOV 1964. More recent studies (e.g. FEDOROWSKI 1980) and a review of the type specimens of Carinthiaphyllum and Lonsdaleoides have shown them to be solitary corals with a gregarious growth habit, which is also common in most other genera of the family (COCKE 1970; RODRIGUEZ 1985). In its original description and in all subsequent works, Darwasophyllum is consistently referred to as a fasciculate coral, but the presence of offsets has not been illustrated in the genus and a colonial growth habit has not been clearly demonstrated. Specimens of Darwasophyllum from the Etherington Formation in Canada, collected near the Visean-Serpukhovian boundary, were initially regarded as fasciculate colonies with long, sub-parallel, closely spaced corallites. When they were studied in detail by means of serial sections, however, these corals were found to be solitary individuals grouped into gregaria, without shared structures or offsets. Thus, true colonies are unknown in the Geyerophyllidae and all genera described as colonial in that family consist of gregarious, solitary corals.