A new species of Cloudina from the terminal Ediacaran of Spain

The terminal Ediacaran genus Cloudina includes some of the earliest biomineralized fossils. It consists of a tube formed by stacked funnel-shaped elements, and is usually interpreted as the external skeleton of an early metazoan. Although a number of species have been described within this genus, their distinctiveness remains unclear and they may all belong to the type species, Cloudina hartmannae Germs, 1972. Here we describe the new species Cloudina carinata, from central Spain. C. carinata n. sp. has a distinct morphology characterized by external longitudinal crests, which confer on the tube an irregular polygonal cross-section. The funnels have a thickened apertural rim and a basal, slightly constricted circular opening. Successive funnels appear less deeply imbricated than in previously described material of Cloudina. The evidence of tube disarticulation in the material studied, particularly the abundance of loose funnels, indicates that funnels were secreted as independent elements, not fused to the previous ones. However, they could become fused during the life of the organism through the precipitation of inorganic cements between their walls. Several specimens of C. carinata n. sp. show evidence of asexual reproduction.