Tildeniella torsiva Mai, Johansen et Pietrasiak, 2018

Mai, Truc, Johansen, Jeffrey R., Pietrasiak, Nicole, Bohunická, Markéta & Martin, Michael P., 2018, Revision of the Synechococcales (Cyanobacteria) through recognition of four families including Oculatellaceae fam. nov. and Trichocoleaceae fam. nov. and six new genera containing 14 species, Phytotaxa 365 (1), pp. 1-59 : 40-42

Tildeniella torsiva Mai, Johansen et Pietrasiak sp. nov.

Diagnosis: ―Morphologically distinguished from T. nuda by the presence of spirally-coiled filaments and falsebranches. Molecularly distinguished by from T. nuda by secondary structures of the D1-D1’ and Box B helices ( Figs. 6n, o , 7m, n ), as well as by the absence of a V2 helix.

Description:— Colony fasciculated, spreading irregularly, forming irregular clumps on the agar, with filaments penetrating the agar, bright blue green, becoming olive green with age. Filaments with rare false branching in older cultures ( Fig. 20a ), often entangled, 1.7–2.5 μm wide. Sheath firm, thin, colorless, up to 0.7 μm wide, often not evident. Trichomes untapered, straight, curved ( Fig. 20b ), or sometimes spirally coiled ( Fig. 20c–d ), slightly constricted at the cross-walls, with cell division occurring throughout the trichome, 1.4–1.9 μm wide. Hormogonia and necridia absent. Cells rarely isodiametric, mostly longer than wide, with contents usually homogeneous, without granulation, varying from 1.5–2.7 μm long. End cells rounded.

D1-D1’ helix 65 nucleotides long, with basal 3’ unilateral bulge of 6 nucleotides (5’-CAUCCA-3’), with one C/U mismatch at position 9/51 and one internal loop at position 20–22/37–40. Terminal loop 4 nucleotides long, 5’-UUCG- 3’ ( Fig. 6n ). Box B helix 49 nucleotides long, with one C/A mismatch at position 6/44 and one unpaired adenine residue at position 18, with terminal loop sequence 5’-AAGG-3’ ( Fig. 7m ). V2 helix absent.V3 helix 92 nucleotides long, with multiple internal loops along the helix at positions 4–5/85–89, 8–9/81–82, 12–16/75–78 and 35–37/54–56. Basal clamp of V3 helix shorter than all other species of Oculatellaceae due to a A/A mismatch (5’-AGUC:GACA-3’ compared to 5’-UGUC:GACA-3’ in other species of Oculatellaceae ) ( Fig. 9l ).

Etymology:— torsivus (L.): spirally coiled.

Type locality: ― Slovakia. National Park Slovak Paradise: Gorge Prielom Hornadu, collected in 1998 by Bohuslav Uher. Found in limestone wall near tourist walkway (strain Uher 1998/13d). Other locality: Bay barther Bodden near bridge Meiningen, Germany (strain Hubel 1974/233).

Holotype here designated:— BRY37781 !, Herbarium for Nonvascular Cryptogams, Monte L. Bean Museum, Provo, Utah.

Reference strain: ―Uher 1998/13d, Algal Culture Collection at John Carroll University, Cleveland, USA. Other reference strain Hubel 1974/233.

Taxonomic notes:— The spirally coiled and contorted filaments as well as the variation in cell length from isodiametric to distinctly longer than wide are considered the most characteristic features in this species. This taxon is a close morphological match to Leptolyngbya thermobia Anagnostidis (2001: 368) and L. lagerheimii ( Gomont 1890 ex Gomont (1892: 147) Anagnostidis & Komárek (1988: 391). L. thermobia was described from thermal waters, and is consequently physiologically distinct from T. torsiva .

L. lagerheimii is very similar to T. torsiva , having similar cell dimensions and loose spiral coiling. L. lagerheimii was originally described from Brazil as Spirocoleus lagerheimii Möbius (1889: 312) . Gomont transferred the species into Lyngbya lagerheimii Gomont (1890: 354) ex Gomont (1892:147) , and this species was later transferred into Leptolyngbya in the same publication in which that genus was described and typified by L. boryana . It was not realized at that time that Spirocoleus lagerheimii had been validated post-starting point by Crow: Spirocoleus lagerheimii (Gomont) Möbius ex Crow (1927:147) . Leptolyngbya was subsequently conserved against Spirocoleus because it was in much wider use (McNeill et al. 2006). The name Spirocoleus is available for use if it can be documented to be phylogenetically outside of Leptolyngbya sensu stricto. However, the loose spirals in trichomes are a trait that is not confined to Tildeniella or Spirocoleus , and so we do not have convincing evidence that these European strains isolated from subaerophytic habitats in Europe belong to the same lineage as S. lagerheimii isolated from stagnant waters in Brazil. If S. lagerheimii could be isolated from Brazil near the type locality, and if its sequence places it in equivalency with T. torsiva , then it would be necessary to transfer T. torsiva and T. nuda to Spirocoleus . For now, we feel it is more conservative to simply describe this lineage as a genus new to science.

Figures

FIGURE 6. D1-D1’ stems of species described in Oculatellaceae.The stem structures of genera described previously in other publications (Oculatella, Thermoleptolyngbya, Timaviella) or in publications under provision (Trichotorquatus) are not shown here.

FIGURE 7. Box B helices of species described in Oculatellaceae. The structures of genera described previously in other publications (Oculatella, Thermoleptolyngbya, Timaviella) or in publications under provision (Trichotorquatus) are not shown here.

FIGURE 9. V3 helices of species described in Oculatellaceae. All species described have this structure. The V3 helix of Cartusia aeruginosa is missing because we do not have the full length of its ITS region.

FIGURE 20. Tildeniella torsiva. A. Single false-branching very rarely observed, only in senescing culture. B. Cells isodiametric to slightly longer than width. C–D. Filaments sometimes wavy to strongly spirally coiled. Scale bar 10μm in 1000X magnification.