Timaviella radians Mai, Johansen et Bohunická, 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 : 36-38

Timaviella radians Mai, Johansen et Bohunická sp. nov.

Diagnosis: ―Differing from T. obliquedivisa in the formation of radial microscopic colonies, color and occasional pigmentation of the trichomes. D1-D1’ helix similar in structure to those of T. obliquedivisa and T. radians , especially in the unilateral bulge sequence, the internal loop at position 14–15/59–60 and the large internal loop at position 20–23/50–54, but differing in length of helix ( Fig. 6j–l ). Box B helix shorter than the Box B helix of other Timaviella species ( Fig. 7i–k ). V2 helix very short, 12 nucleotides ( Fig. 8i ).

Description:— Colony mounded, leathery, dark olive-brown or dirty olive-green. Filaments relatively short, often clearly widened in meristematic zones ( Fig. 18a–b ), sometimes forming radial colonies ( Figs. 18c ), with characteristic consecutive false branching ( Fig. 18d ). Sheath usually thin and scarcely visible to widened and evident, rarely extended past the apical end of trichome. Trichomes brownish when actively growing, olive-green when approaching senescence, constricted at distinctly visible cross-walls, occasionally forming compact rope-like coils at meristematic or active division zone ( Fig. 18a, e ), 1.8–3.7 μm wide. Necridia absent. Hormogonia without sheaths ( Fig. 18d, f ). Cells in hormogonia and young filaments isodiametric, becoming shorter than wide with maturation 1.2–2.2 μm long, often with one large central granule, often with purplish pigmentation ( Fig. 18f ). Apical cell rounded, conically rounded, or pancake-like rounded.

D1-D1’ helix 81 nucleotides long, with a 3’ unilateral bulge of 8 nucleotides (5’-CAUCCCAA-3’); mid-helix with several internal loops at position 14–15/59–60, 20–23/50–54, 26–27/46–47 and a nucleotide mismatch of G/G at position 30/43, with. terminal loop having sequence 5’-GAGA-3’ ( Fig. 6l ). Box B helix 33 nucleotides long, with two internal loops at positions 5/28–29 and 8–9/25; terminal loop having sequence 5’-UAAUA-3’ ( Fig. 7k ). V2 helix very short ( Fig. 8i ). V3 helix 59 nucleotides long, with one internal loop at position 5/53–55 and two unpaired adenine residues at positions 48 and 44 of the 3’ strand ( Fig. 9k ).

Etymology:— radians (L.): radiating, for the radiating pattern of filaments in the colonies.

Type locality: ―Lower Calf Creek Falls site, Grand Staircase-Escalante National Monument, 37°49’44.77’’ N-111 °25’12.58”W, collected on 15 August 2006 by Markéta Bohunická. Large seep wall and waterfall in Navajo Sandstone, in the GSENM, Kane County, Utah, USA. Mats in waterfall.

Holotype here designated:— BRY37789 !, Herbarium for Nonvascular Cryptogams, Monte L. Bean Museum, Provo, Utah.

Reference strain: ―GSE-UNK-7 R, Algal Culture Collection at John Carroll University, Cleveland, USA.

Taxonomic notes:— Our strain closely resembles Leptolyngbya gracillima (Zopf ex Hansgirg 1892: 41) Anagnostidis & Komárek (1988: 391) . It matches the recent description of this widely-reported taxon in Komárek & Anagnostidis (2005), with the exception that cells in that species are isodiametric to longer than wide instead of isodiametric to shorter than wide, as seen in T. radians . The radial arrangements of filaments and the occasional coiling have also not been observed in L. gracillima material. This taxon is interesting as it was originally described as Glaucothrix gracillima Zopf (1882:44) , named Plectonema gracillimum Hansgirg (1887: 108) , and then validated post-starting point ( Gomont 1892) by Hansgirg (1892:41). A lectotype specimen for the taxon was designated by Drouet (1968:41), who chose a herbarium sample collected by P. Richter from wet walls in a warm spring near Anger, Bavaria, Germany deposited in the Drouet Collection at the Smithsonian Institution (Alg. Exs. No. 593a). This was perhaps an unfortunate choice for the lectotype, as the original material of Zopf was not collected from a warm spring, but it remains a validly designated lectotype. Even though the descriptions of Zopf (1882) and subsequent authors matches our taxon fairly closely, this lectotype does not, as thermal springs in Germany are a very different habitat than a waterfall in a desert in North America. T. radians and T. obliquedivisa were similar in 16S rRNA gene sequence (96.45%, Table 11), had very similar lengths of conserved domains in the ITS region ( Table 6), and had similar ITS structures, but distinctive molecular and morphological features well separate the two species. T. radians has a markedly different structure in the D1-D1’, Box-B, and V 3 helices than the earlier described species, T. circinata Sciuto et al. (2017: 319 , figs. 3–5) and T. karstica Sciuto et al. (2017: 319 , figs. 3–5). T. obliquedivisa and Timaviella species WMT-WP7- NPA collected from the White Mountains share 99.05% identity in the 16S rRNA gene ( Table 11) sequence, but are greatly different in the ITS region (p=18.3%, Table 12) and their ITS structures ( Figs. 6–9 ). All Timaviella species described to date are reported from wet rock faces in grottos or caves, although T. circinata and T. karstica are from karstic rocks in an alpine region in the Italian Alps, while the species described in this paper are from sandstone seeps in the arid canyon country of Utah, USA.

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 8. V2 helices of species described in Oculatellaceae. Several species do not have this structure, including Pegethrix convoluta, P. indistincta, Antartic Pegethrix species, Cartusia fontana¸ Kaiparowitsia implicata.

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 18. Timaviella radians. A–B. Rapid cell division at apical region commonly observed, forming a “basal” part to filament. C. Radial formation of colonies based on trichomes radiating from an attachment point. D. False-branches in singles or in pairs, consecutive, sometimes geminate branching, E. Compact rope-like coils. F. Rapid cell division causing twists and turn of trichome within sheath. Mature filaments isodiametric, trichomes constricted at distinct cross-walls, with one large central granule dominates cytoplasm. Scale bar 10μm in 400X (C) and 1000X magnification (A–B, D–F).