The Molecular Phylogenetic and Geometric Morphometric Evaluation of Micrasterias Crux-Melitensis/M. Radians Species Complex1

Abstract

We investigated nine strains of the Micrasterias crux-melitensis (Ehrenb.) Hassall ex Ralfs and M. radians W. B. Turner species complex. A combination of molecular, morphological, and geometric morphometric data was used to reveal the patterns of their phenotypic and phylogenetic differentiation. The molecular data based on internal transcribed spacer (ITS) rDNA, glycine transfer RNA (trnG uuc ) intron, and SSU rDNA sequences revealed three phylogenetic lineages. One of them comprised the six European and North American strains that were morphologically identified as M. crux-melitensis. Phenotypic data illustrated high morphological variability of strains within this genetically homogenous lineage that spanned several traditional infraspecific taxa, including strains corresponding to M. crux-melitensis var. janeira (Racib.) Grönblad and M. crux-melitensis var. superflua W. B. Turner, whose morphometric characteristics profoundly differed. Three strains of M. radians formed two separate phylogenetic lineages corresponding to traditional varieties M. radians var. evoluta (W. B. Turner) Willi Krieg. and M. radians var. bogoriensis (C. J. Bernard) G. S. West. The morphological types corresponding to the former variety have, so far, only been reported from Africa. Therefore, we cannot preclude that geographic isolation may play a role in species differentiation of relatively large freshwater protists, such as Micrasterias.

New and remarkable desmids (Zygnematophyceae, Streptophyta) from Europe: taxonomical notes based on LM and SEM observations.

“…This has also been concluded by other authors (e.g. coesel 1984; Gontcharov et al 2002;neustupa et al 2010) and its full potential obviously hasn't been realized yet. This especially concerns smaller forms with few morphological characteristics where it may be used for the delimitation of (pseudo)cryptic species.…”

“…This trend has been convincingly demonstrated in several recent papers (e.g. neustupa et al 2010, 2011neMjová et al 2011). In our opinion, it can be assumed that the estimation of the overall global desmid species number by hoshaw et al (1990, 15000 spp.…”

“…Mccourt et al 2000;Gontcharov et al 2003;neustupa & ŠKaloud 2007;Gontcharov 2008;hall et al 2008;Gontcharov & MelKonian 2005. Only very recently molecular methods have also been used in the evaluation of taxonomic concepts of traditional, morphology-based taxa at the level of species and variety, resulting in remarkable taxonomic changes (neustupa et al 2010, 2011neMjová et al 2011).…”

New or otherwise interesting desmid taxa from the Bangweulu region (Zambia). 1. Genera Micrasterias and Allorgeia (Desmidiales)

“…Genbank data of a M. crux-melitensis strain from the Japanese NIES culture collection, however, showed a closer affiliation with M. radians var. evoluta than with the analyzed strains of European/North American M. crux-melitensis (Neustupa et al 2010). Photographs of the strain NIES-152 indicate that this strain morphologically is more similar to M. radians than to M. crux-melitensis, suggesting a possible misidentification (National Institute for Environmental Studies 2014).…”

“…This could better explain the gradual transition found by those authors between 'typical' M. radians in tropical lowland waters and their supposed M. crux-melitensis in high altitude Papua New Guinea lakes. Interestingly, Neustupa et al (2010) based on molecular data found some six European and North American strains of M. crux-melitensis to belong to another phylogenetic lineage than two Kenia strains of M. radians var. evoluta.…”