title: Chalicogloea cavernicola gen. nov., sp. nov. (Chroococcales, Cyanobacteria), from low-light aerophytic environments: combined molecular, phenotypic and ecological criteria.
abstract: This work characterizes a unicellular cyanobacterium with nearly spherical cells and thin-outlined sheaths that divide irregularly, forming small packets immersed in a diffluent mucilaginous layer. It was isolated growing on calcite speleothems and walls in a show cave in Collbató (Barcelona, Spain). Spectral confocal laser and transmission electron microscopy were used to describe the morphology, fine structure and thylakoid arrangement. The pigments identified were phycoerythrin, phycocyanin, allophycocyanin and chlorophyll a. Three-dimensional reconstructions, generated from natural fluorescence z-stacks, revealed a large surface area of nearly flat, arm-like thylakoidal membranes connected to each other and forming a unified structure in a way that, to our knowledge, has never been described before. Phylogenetic analyses using the 16S rRNA gene sequence showed 95% similarity to strain Chroococcus sp. JJCM (GenBank accession no. AM710384). The diacritical phenotypic features do not correspond to any species currently described, and the genetic traits support the strain being classified as the first member of an independent genus in the order Chroococcales and the family Chroococcaceae. Hence, we propose the name Chalicogloea cavernicola gen. nov., sp. nov. under the provisions of the International Code of Nomenclature for Algae, Fungi and Plants. The type strain of Chalicogloea cavernicola is COLL 3(T) (=CCALA 975(T) =CCAP 1424/1(T)).
authors.affiliation: Dep. Productes Naturals, Biologia Vegetal i Edafologia, Unitat de Botànica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain.|Servei de Microscòpia, Universitat Autònoma de Barcelona, Edifici C, Facultat de Ciències, 08193 Bellaterra, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Roldán
authors.affiliation: Dep. Productes Naturals, Biologia Vegetal i Edafologia, Unitat de Botànica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Ramírez
authors.affiliation: Institut de Biologia Evolutiva, CSIC-UPF, Passeig Marítim de la Barceloneta, 37-49, 08003 Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Del Campo
authors.affiliation: Dep. Productes Naturals, Biologia Vegetal i Edafologia, Unitat de Botànica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Hernández-Mariné
authors.affiliation: Institute of Botany, Academy of Sciences of the Czech Republic, Dukelská 135, CZ-37982 Třeboň, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Komárek
mesh_terms: D059552:Caves / Q000382:microbiology*; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D000458:Cyanobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010798:Phycocyanin / Q000032:analysis; D010799:Phycoerythrin / Q000032:analysis; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013030:Spain; D020524:Thylakoids / Q000648:ultrastructure
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; C002497:allophycocyanin; D010798:Phycocyanin; D010799:Phycoerythrin; D002734:Chlorophyll; D000077194:Chlorophyll A