MORPHOLOGY, ECOLOGY AND DISTRIBUTION OF AN ENDEMIC ANTARCTIC LACUSTRINE DIATOM: CHAMAEPINNULARIA CYMATOPLEURA COMB. NOV.

Abstract

Specimens belonging to the diatom species Pinnularia cymatopleura collected from benthic cyanobacterial mats of lakes and ponds in Continental Antarctica were examined. In addiction, slides from the West & West collection which contain isotypes of this taxon were also investigated. Light Microscope (LM) and Scanning Electron Microscope (SEM) studies of this diatom reveal that its valve structure possesses features typical of the recently established diatom genus Chamaepinnularia. The most important features that justify the allocation of this taxon to Chamaepinnularia are:

	— the presence of uniseriate striae composed of alveoli occluded by external hymenes;
	— the absence of multiseriate round poroids in the outer wall;
	— internally an apical series of apertures, located on the valve face separated from a second series on the valve mantle.

The new combination Chamaepinnularia cymatopleura (West & G. S. West) Cavacini is proposed. This highly tolerant to salinity taxon is currently only known from a few zones of Continental Antarctica. The absence of records of this taxon in Maritime- and Sub-Antarctica, Australia and South America seem to justify the classification of this species as “endemic to Continental Antarctica”.