Seven new species ofOculatella(Pseudanabaenales, Cyanobacteria): taxonomically recognizing cryptic diversification

Abstract

A total of 27 strains of Oculatella were isolated, characterized and sequenced, and analysed phylogenetically with an additional environmental clone from the Atacama Desert and 10 strains isolated and sequenced by others. The strains were clearly separated based upon phylogenetic analyses conducted with a concatenated alignment of the 16S rRNA and 16S-23S ITS region of the ribosomal operons in the genus Oculatella. Differences in secondary structure of the conserved domains of the ITS region, as well as comparative analysis of P-distance among ITS regions, served to separate the strains into distinct taxonomic units. Seven new species of Oculatella were described, including four from arid to semi-arid soils (O. atacamensis, O. mojaviensis, O. coburnii, O. neakameniensis) and three from more mesic habitats, including a temperate lake (O. hafneriensis), a desert waterfall (O. cataractarum) and a Hawaiian sea cave (O. kauaiensis). The soil forms show statistically significant morphological differences, but the ranges overlap to a degree that they are not diagnosable by morphology, and these four cryptic species are characterized here using molecular characters. The more mesic species, including the type species from Mediterranean hypogea, O. subterranea, are all morphologically distinct from each other and from all four soil taxa. This report is the first to use solely molecular criteria to distinguish cryptic species of cyanobacteria.

Species concepts and speciation factors in cyanobacteria, with connection to the problems of diversity and classification

“…They also designed a concrete species definition based on the mentioned concept, which is suitable for cyanobacteria and may be used under the International Code of Botanical Nomenclature. It is probably the most widely accepted concept with cyanobacteria (according to the number of taxonomic papers using the concept under the Botanical Code), although sometimes not precisely followed (Siegesmund et al 2008;Perkerson et al 2011;Dvořák et al 2014a;Hašler et al 2012Hašler et al , 2014aOsorio-Santos et al 2014 and many others). The most important advantage of the monophyletic species concept is the general applicability to asexual organisms.…”

Limnolyngbya circumcreta gen.&comb. nov. (Synechococcales, Cyanobacteria) with three geographical (provincial) genotypes in China

“…Interestingly, these three separate subclades comprised strains from three different provinces in China, suggesting that the species L. circumcreta might be subject to geographical distribution. The process of speciation first begins with a vicariance event, after which evolutionary species can be diagnosed when some phyletic changes (diagnosable in morphology) occur with the passage of time (Mishler & Theriot 2000;Osorio-Santos et al 2014). However, when phyletic changes first occur with cryptic phenotypic characters (e.g.…”

Difference without distinction? Gaps in cyanobacterial systematics; when more is just too much

“…Thus, we may anticipate further disagreement of molecular data with traditional systems. Similarly, extensive evidence of polyphyly has been found in other taxa-rich genera such as Leptolyngbya (Osorio-Santos et al 2014;Jahodářová et al 2017), Phormidium (Hašler et al 2012), or Cylindrospermum .…”

“…Thus, additional data, such as provided by the ITS region rbcL gene sequences, are increasingly being employed (e.g. Osorio-Santos et al 2014). While traditional employment of the 16S rRNA gene might be sufficient for generic level assignments, we see many misidentified strains due to the polyphyletic nature of many currently circumscribed genera (Komárek et al 2014).…”

“…For example, PTP recognized 6 of 7 PTP-defined species within Oculatella (except O. mojaviensis; Osorio-Santos et al 2014), while O. subterranea was divided into three PTP-defined species. In the genus Nodosilinea, only one species (Nodosilinea sp.…”