Iberiaella, a new fossil alga from the Middle Carboniferous of NW Spain

Abstract

A colony-forming organism, constructed of single, pairs or bundles of wavy, locally constricted tubular filaments, is described here as new Middle Carboniferous algal genus Iberiaella of uncertain affinity. Iberiaella superficially resembles Donezella, a widespread organism observed in shallow water carbonates of the Cantabrian Mountains. However, the multi-layered tubular tissue, the nonperforated wall structure of the tubes and the encrusting habitus make Iberiaella easily distinguishable from Donezella with its dichotomously branching single layers of detached septated tubes. It is believed that lberiaella with its anastomosing branching-network and encrusting character forms the rigid skeleton of the organic mounds which occur commonly in the carbonate beds on the southern slope of the Cantabrian Mountains. Donezella had the function of a stabilizer in the process. The fine (micritic) internal sediment - the bulk of the material filling up the open spaces in the algal network - suggests low to moderate energy during deposition and absence of drastic diagenetic alterations.