Brachiopod and fusulinid assemblages of Kasimovian (Pennsylvanian) age from the Ándara Massif (Picos de Europa, northern Spain)

The analysis of early Kasimovian (Pennsylvanian) brachiopod assemblages from two fossiliferous localities of the Las Llacerias Formation (Ándara Massif, Picos de Europa, northern Spain) improve our knowledge of this fossil group in the Cantabrian Zone. At the Morra de Lechugales Peak (locality 1), marlstones and bioclastic limestones, accumulated in a low energy, subtidal, aphotic setting, characterize a soft muddy sea-floor affected by periodic intense bottom currents and provide a rich assemblage of brachiopods together with other macrofossils. Brachiopod specimens are characterized by their small size (<10 mm) and belong to 38 different taxa. The fossiliferous dark marly limestones at the Castillo del Grajal (locality 2) record a very shallow water, low energy, subtidal and photic environment, where bioclastic wackestone-packstone accumulated in a relatively clean and clear sea-water. Very diverse biotic associations including abundant photozoans and heterozoans characterize these strata. Brachiopod assemblages from this locality share 12 genera and five species with locality 1, but they also show striking differences such as the absence in the locality 2 of representatives of the family Spiriferellidae and the order Spiriferinida; moreover, the specimens from the last locality are of normal size. These differences are interpreted to be the result of very different environmental conditions between localities during the interval under consideration. Fusulinids studied from the Las Llacerias Formation allow correlation of the two fossiliferous localities with the lower Kasimovian. The representatives of the family Spiriferellidae are described. They include the new species Plicatospiriferella winklerprinsi, a small sized form with slightly transverse shell, dorsal valve slightly convex, strongly incurved ventral umbo and simple plicae on flanks. The new genus Winklerprinsia (type species Winklerprinsia europea sp. nov.) is included in the family because of its plicate flanks, pustulose microornament, ventral umbonal region thickened by a callus and short dental adminicula. The most distinctive feature of the new genus is a solid, elevated ventral platform, interpreted as a muscle platform. A new fusulinid species, Protriticites winkleri, is described from the Morra de Lechugales Peak section. Its overall characteristics somewhat resemble forms assigned in other areas of the world to Obsoletes, but its wall microstructure corresponds to that of Protriticites species.