Roholtiella mojaviensis Pietrasiak et Johansen, 2015

Bohunická, Markéta, Pietrasiak, Nicole, Johansen, Jeffrey R., Gómez, Esther Berrendero, Hauer, Tomáš, Gaysina, Lira A. & Lukešová, Alena, 2015, Roholtiella, gen. nov. (Nostocales, Cyanobacteria) - a tapering and branching cyanobacteria of the family Nostocaceae, Phytotaxa 197 (2), pp. 84-103 : 92-93

Roholtiella mojaviensis Pietrasiak et Johansen , spec. nov. ( Figs. 3A–S )

Differing from all other species by having shorter, narrower, more consistently tapered trichomes ( Table 2) and bright blue-green pigmentation and desert soil habitat. Also differing from all other species in the sequence of the flanking regions of the Box-B and V3 helices of the 16S-23S ITS region ( Fig. 5 ).

Type: — USA. Microscopic in sandy, gravelly soil from granitic outcrops, with plants and well-developed algal crusts, Joshua Tree National Park, Wonderland of Rocks, CA, N. Pietrasiak, June 2006 (holotype: CBFS! A-039-1). Refence strain: CCALA 1051.

bold. [x] row of arthrospores within the sheath, not yet released, (x) observed exceptionally.

Description: —Thallus evenly flat, spreading, appressed to the agar surface, growing into the substrate, blue-green to olive-green, rarely turning brown. Filaments short, sometimes single ( Figs. 3E, K ) or more rarely double ( Fig. 3D ) false branched. Sheath thin, attached, rarely widened and lamellated ( Figs. 3L, S ), firm, colorless to slightly pinkish ( Fig. 3S ). Trichomes constricted at crosswalls, slightly to distinctly tapered towards ends, commonly Calothrix -like with basal heterocyte at the slightly widened base, 5.7–9.6 μm wide. Cells shorter than wide, rarely longer than wide, cylindrical, barrel-shaped or compressed spherical, with smooth content, blue-green to olive-green, 1.6–7.3 μm long. End cells conical-rounded ( Figs. 3B–C, I ) or conical ( Figs. 3A, D, S ), 2.8–5.2 μm wide, 3.2–6.4 μm long. Heterocytes terminal, hemispherical or slightly conical, rarely intercalary in pairs, yellow or tan, 4.3–7.4 μm wide, 3.2–6.8 μm long. Arthrospores or rows of arthrospores released from the ends of the filament, with thick cell wall, almost spherical, olive-green, 5.6–7.9 μm wide, 4.1–9.0 μm long. Hormogonia constricted at crosswalls, typically 8–12 celled ( Fig. 3A ), without sheath or with sheath thin, attached, with cells 2.8–4.2 μm wide, 1.6–41 μm long.

Habitat: —desert soil.

Etymology: —From the Latin mojaviensis (= from Mojave Desert, USA), referring to the geographical origin of the taxon.

Other strain: —CCALA 1052 (CBFS! A–040-1)

Figures

FIGURE 3. A–S. Roholtiella mojaviensis, sp. nov. A. Hormogonia. B–C. Maturing hormogonia. D–H, L–M. Tapered Calothrix-like filaments. E. False branching. H. Isopolar filament with two adjacent intercalary heterocytes, arrow marks a point of subsequent breakage. I–J. Mature filaments with near-spherical cells. K. False branching. N–Q. Rows of arthrospores. R. Releasing of arthrospores from the opened end of the filament. S. Mature tapered filament with thick structured colored sheath. Strains used in this figure: CCALA 1051 = A, D–I, K–O, Q–R, CCALA 1052 = B–C, J, P, S. Scale bar applies to all figures, in A–J and L–S = 20 μm, in K = 50 μm.

FIGURE 5. Sequence of 16S-23S ITS flanking regions of the BoxB and V3 helices for Roholtiella species. Base pair position shown above sequences, with sequences of BoxB, BoxA-D4, and V3 not shown. Variable bases shaded in gray.