Taxonomic revision of Chamaepinnularia krookiformis Lange-Bertalot et Krammer with a description of Chamaepinnularia plinskii sp. nov.

Abstract

The benthic diatoms collected during our recent research in athalassic habitats exemplify a high morphological variability within Chamaepinnularia krookiformis Lange-Bertalot et Krammer. The species has already been known from freshwater ecosystems as well as from brackish waters in different regions of Europe. This variability has been also confirmed by the analysis of the literature. However, this is the first time that the morphological variability of the species has been addressed. In order to revise C. krookiformis and describe a new species, which has been distinguished on the basis of our material, we compared it with the type material of Pinnularia krookiformis Krammer 1992 from the periodic saline pool in Nordrhein-Westfalen (Germany). This study deals with a morphological analysis based on a large populations of C. krookiformis from Pelczyska (Central Poland). Selected morphological features were analysed, i.e.: valve length and width, number of striae in 10 µm, apices width, constrictions width, apices/constrictions width ratio, central-area length, and valve/central area length ratio. The results of light (LM) and scanning (SEM) microscopy, supported by multidimensional scaling (MDS), allowed for the distinction of three different morphotypes. Two of them match Krammer concept of Pinnularia krookiformis from 1992, while the third, occurring in our samples in three sampling sites, is clearly different. Thus, we described a new species Chamaepinnularia plinskii sp. nov., by the following major features: the valves are linear, symmetric, with rounded, capitate apices, the axial area is narrow, expanding to a wide central area forming a fascia, distal raphe endings are hooked to the same side of the valve and striae slightly radiate in the middle and in the rounded apices, becoming parallel in constrictions, 20-26 in 10 µm. This species occurs in inland waters with a wide range of chloride concentration, from 1000 to 3500 mg.l-1.