Roholtiella, gen. nov. (Nostocales, Cyanobacteria)—a tapering and branching cyanobacteria of the family Nostocaceae

Abstract

A total of 16 strains phylogenetically placed within the Nostocaceae were found to possess morphological features of the Rivulariaceae and Tolypothrichaceae (tapering trichomes and single false branching, respectively) in addition to their typical Nostocacean features (production of arthrospores in series). These strains formed a strongly supported clade separate from other strains that are phylogenetically and morphologically close. We describe four new species within the genus Roholtiella gen. nov. The four species include three distinguishable morphotypes. Roholtiella mojaviensis and R. edaphica are morphologically distinct from each other and from the other two species, R. fluviatilis and R. bashkiriorum. Roholtiella fluviatilis and R. bashkiriorum are cryptic species with respect to each other. All four species are easily distinguished based on the sequence of the 16S-23S ITS regions, in particular the flanking regions to the conserved Box-B and V3 helices. The species are further established by the elevated p-distance between species that is much reduced among strains within the same species. Calochaete cimrmanii, a recently described tapering species from tropical biomes, is the most likely sister taxon to Roholtiella.

Nodosilinea chupicuarensis sp. nov. (Leptolyngbyaceae, Synechococcales) a subaerial cyanobacterium isolated from a stone monument in central Mexico

“…The analysis of the more variable 16S-23S internal transcribed spacer (ITS), including secondary structure, length of conserved domains, p-distance, and phylogenetic analysis, is a better tool for separation of species, and has been validated in a number of studies (Řeháková et al 2007, Perkerson et al 2011, Vaccarino & Johansen 2012, Osorio-Santos et al 2014Bohunická et al 2015, Miscoe et al 2016, Sciuto & Moro 2016, Berrendero Gómez et al 2016. The 16S-23S ITS p-distance between N. chupicuarensis and N. nodulosa is 0.082 (Table 1), which we take as strong evidence that our strain is separate from that taxon.…”

Phylogenetic position reevaluation of Kyrtuthrix and description of a new species K. huatulcensis from Mexico´s Pacific coast

“…Not only are new species and genera being described, but new taxa are also being created as existing species are being transferred to different genera, families or orders with the advent of the polyphasic approach which incorporates morphological, ecological, and molecular data into our understanding of what constitutes cyanobacterial taxa (Komárek et al 2014). Molecular markers such as the 16S rRNA gene have been proven to give valuable information for comparing and helping to solve phylogenetic relationships at generic and family levels (Fiore et al 2007, Hauer et al 2014, Mareš et al 2015, and the characterization of the secondary structure of the 16S-23S (ITS) region has been useful in separation of morphologically similar species (Perkerson et al 2011, Osorio-Santos et al 2014, Bohunická et al 2015.…”

Taxonomic resolution of the genus Cyanothece (Chroococcales, Cyanobacteria), with a treatment on Gloeothece and three new genera, Crocosphaera, Rippkaea, and Zehria

“…, Bohunická et al. ). Moreover, gathering all available informative data on morphology, cell ultrastructure, ecology, physiology, or biochemical traits is recommended as the best practice for identification of established taxa.…”