Falsocalcifolium nov. gen. and revision of the tribe Calcifolieae (Mississippian, incertae sedis algae)

A new genus, Falsocalcifolium is described. The type species is F. punctatum (Maslov) emend. The genus is placed in the tribe Calcifolieae Shuysky emend. of the family Calcifoliaceae Termier, Termier and Vachard nomen translat. Consequently, the generic make-up of the tribe is emended, and is now considered to be composed of Frustulata Saltovskaya emend., Falsocalcifolium nov. gen., and Calcifolium Shvetsov and Birina emend. Evolution within the tribe is shown by the progressive development of more petaloid morphologies and changes in the number and relationships of the internal structures called filaments (interpreted here as the emplacements containing endosymbiotic cyanobacteria). This evolution is also related to palaeoecological factors. The representatives of the tribe are considered excellent biostratigraphic markers in several western Tethyan regions (e.g. Great Britain, Ireland, southern France, southern Spain), where they are widely represented, but their geographical distribution in other basins seems to be incomplete, and thus their use in biostratigraphic correlation is at the moment limited.