Nannotax

Description: Coccosphere with rhombic muroliths with central area floored by transverse laths (scapholiths); monomorphic or dimorphic.

Remarks:

Type species: C. murrayi.

Synonyms:

• Acanthosolenia Bernard 1939
• Anoplosolenia Deflandre 1952
• Scapholithus Deflandre 1954

NB The monomorphic species C. brasiliensis has often been placed in a separate genus, Anoplosolenia, leaving the dimorphic species C. murrayi in Calciosolenia. Following Young et al. (2003) we prefer to include both species in a single genus, since the coccolith structure of the two species is identical and their affinity is not in dispute. Including the two species in one genus makes this affinity clearer, reduces the number of monospecific genera, and avoids the problem of having generic concepts which cannot be applied to isolated coccoliths in the fossil record. As a result, the artificial genus Scapholithus, which has often been used by palaeontologists for isolated scapholiths, is redundant, all such specimens can be included in Calciosolenia.

Since fossil specimens cannot usually be confidently assigned to either C. murrayi or C. brasiliensis the best identficaton is usually Calciosolenia sp.