The subaerophytic cyanobacteriumOculatella subterranea(Oscillatoriales, Cyanophyceae)gen. et sp. nov.: a cytomorphological and molecular description

Abstract

A new genus and species of subaerophytic cyanobacteria with very thin purple-red trichomes are described. The seven strains included in this genus were isolated from phototrophic biofilms growing on calcareous substrata in ancient hypogea. Trichomes were 1-3 mm thick, with small constrictions at the cross-walls and colourless sheaths. The thylakoid arrangement was parietal. Autapomorphic characters include the purple-red colouration of cells and a photosensitive orange spot at the tip of the trichome containing a rhodopsin-like pigment. Molecular and phylogenetic analyses based on 16 S rRNA gene sequences, resulted in a new 16 S rRNA cluster that indicated a separate position at the generic level. All strains were closely related (99% or higher similarity) and distantly related to other established cyanobacterial taxa (92%). The 16 S-23 S rRNA internal transcribed spacer (ITS) sequence of five of the red strains was almost identical. The ITS secondary folding structure was also unique to these strains and different to the Leptolyngbya type species. These strains have only been isolated from subterranean environments so far, and considering also this unique biotope and their particular ecology, we propose the new genus and species Oculatella subterranea. The genus name Oculatella means 'provided with a small eye'. The new genus is described using combined molecular and cytomorphological criteria, in accordance with the nomenclatorial recommendations of both the Bacteriological Code and the Botanical Code of Nomenclature. The genus Oculatella is of common distribution in hypogea and has been isolated from all hypogean environments so far studied in Rome and Malta. The type strain is VRUC135.

The deterioration of Circular Mausoleum, Roman Necropolis of Carmona, Spain

“…The genus Oculatella (Zammit et al, 2012) and the species Oculatella subterranea, was established after the study of some Roman and Maltese catacombs applying a combination of both morphological and molecular data. The main morphological features of Oculatella are the red-purple coloration of cells and the presence of an orange photoreceptive structure at the trichomes tips.…”

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

“…Moreover, with higher resolution abilities, we can expect a further expansion of the number of described taxa. For example, Oculatella erected with single species (Zammit et al 2012) now contains seven species, which have been described by different researchers. Thus, even the most liberal estimates may be undervalued.…”

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

“…Unfortunately, this circumscription is so broad that numerous genetically distinct strains and species were assigned to Leptolyngbya based on morphology, even though recent phylogenetic studies have demonstrated that the genus is polyphyletic and in need of taxonomic revision , Osorio-Santos et al 2014. This revisionary work has commenced, and over a dozen novel genera have been split out of Leptolyngbya thus far (Abed et al 2002, Turicchia et al 2009, Perkerson et al 2011, Taton et al 2011, Zammit et al 2012, Dadheech et al 2012, Vaz et al 2015, Song et al 2015a, 2015b, Miscoe et al, 2016, Sciuto et Moro 2016, Sciuto et al 2017, Strunecký et al 2017.…”