Girvanella‐like structures formed byPlectonema gloeophilum(Cyanophyta) from the Borrego Desert in Southern California

Abstract

An example of a recent tubiform fossil Girvanella is reported from a transitory, freshwater flash-spring, in an area of the Borrego Desert, near San Diego, California. It occurs as the preserved, calcite-impregnated sheath of the blue-green alga Plectonema gloeophilum Borzi. In size and form, the fossil is identical to the 1st specific description of a recent Girvanella. The data presented give strong support to the idea of specificity for calcification in some blue-green algae.