Hidden generic diversity in desmids: description of Pseudomicrasterias gen. nov. (Desmidiaceae, Zygnematophyceae)
Abstract
The taxonomy and nomenclature of Micrasterias arcuata are very problematic because of a wide morphological variation and the large number of poorly circumscribed infraspecific taxa. This study aimed at evaluating the phylogenetic position of strains traditionally assigned to M. arcuata based on molecular and phylogenetic approaches, and morphometric analyses.
Multigene analyses were performed using the nuclear SSU rDNA and both chloroplast rbcL and psaA markers. Genetic analyses revealed that all three investigated strains of M. arcuata formed reasonably well-supported lineages, separate from all species of the core Micrasterias lineage and closely related to the Euastrum 2 lineage.
Morphometric analyses exhibited differences among strains revealing important trends for morphological differentiation and delimitation of infraspecific taxa assigned to M. arcuata. All three investigated strains are separated by their morphological features and represent different taxonomic entities from the molecular and phylogenetic points of view.
Available data support the proposal of Pseudomicrasterias gen. nov. within the family Desmidiaceae. One infraspecific taxon is erected to species level and classified as new combination of Pseudomicrasterias, and two new species are recognized.