Chrysochromulina hirtasp. nov., a widely distributed species with unusual spines

Abstract

The external morphology of C. hirta sp. nov., has been described and illustrated from wild material collected in Europe, S. Africa, S. Alaska and arctic Canada, identification being mainly based on the highly characteristic periplast. This contains three different types of scale, including spines of two sizes, both uniformly distributed over the cell and each attached centrally to a strongly concave base-plate with similar surface patterning but with minor dimensional differences. Each spine is also supported laterally by four struts with characteristic differences of detail in the two sizes. Though superficially radial, all spines are in fact bilaterally symmetrical and flattened. Each is also locally twisted into a right handed screw, thereby contributing to mechanical stability in spite of exceptionally high length: width ratios. The species is not only widespread in both hemispheres but is often extremely abundant in temperate coastal waters.