Desmids (Zygnematophyceae) from the littoral zone of an urban artificial lake: Taxonomic aspects and geographical distribution

Abstract

Aim: The aim of this study was to assess the taxonomic aspects and geographical distribution of the periphytic desmids from two different substrates in the littoral zone of an urban artificial lake. Methods: Samples of epiphytic and epilithic desmids were collected by grass and rock scraping, respectively, in two stations in the Cascavel municipal lake, Paraná, during April 2015, and March 2016 and 2017. In the laboratory, the taxa obtained from the samples were photographed and their morphometric characteristics recorded. The species composition of the desmid was characterized, and the frequency of occurrence as well as the geographic distribution of each taxon in the Paraná State were recorded. Results: We identified 35 taxa, distributed in 10 genera. The most representative were Closterium Nitzsch ex Ralfs and Cosmarium Corda ex Ralfs. A high occurrence of sporadic taxa (60%) was observed and among the recorded taxa, the most frequent were Cosmarium pseudoconnatum Nordstedt var. pseudoconnatum and Desmidium grevillei (Kützing ex Ralfs) De Bary. Nine taxa were exclusive to the epilithic substrate and only Netrium digitus (Ralfs) Itzigsohn & Rothe var. digitus was exclusive to the epiphytic substrate, while the remaining 25 taxa occurred in both substrates. Seven taxa are new records for the Paraná State. Conclusion: Although our results are of qualitative nature, they provide baseline data on the biogeographic distribution of taxa, which are crucial for future taxonomic and ecological studies that might contribute to the preservation of the biodiversity.