An Upper Mississippian echinoderm microfauna from the Genicera Formation of northern León (Carboniferous, Cantabrian Mountains, N Spain)

Resumen

For the first time an echinoderm microfauna is recorded from the cephalopod limestone facies (‘griotte facies’) of the lower Carboniferous (Mississippian) Genicera Fm. (Alba Fm.). The formation is widespread in the Cantabrian Mountains in NW Spain, but the ossicles are from some sections in the surroundings of the Bernesga valley in northern León. They have been derived from insoluble acetic acid residues from samples of the upper and especially of the uppermost part of the formation (Canalón Mb. and Millaró Beds). The microfauna include taxonomically treated wheel-shaped ossicles, sieve-plates and rods of holothurians, goniodonts of ophiocistioids, and ophiuroid and stenuroid skeletal elements. From the Palaeozoic of Spain, Ophiocistioidea, Stenuroidea, Apodida (Holothuroidea), and allagecrinids (microcrinoids) are first reported. Here, we describe two new species: Linguaserra heidii n. sp. (Ophiocistioidea) and Calclyra bifida n. sp. (Ophiuroidea). Indeterminate echinoderm remains are also figured and discussed. The findings stress the importance of a diverse but still poorly documented echinoderm fauna in Upper Mississippian psychrospheric pelagic environments.