Pegethrix indistincta Mai et al.

Mai T., Johansen J.R., Pietrasiak N., Bohunická M., Martin M.P. 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, 2018. Vol. 365 (1): 001-059.

Morphologically intermediate between other species, differing in the absence of spiraling and nodule formation; with conserved ITS domains almost identical in shape to D1-D1’ helix of P. convoluta (Fig. 6d). Distinguishable from this species in the adenine residue opposite the basal 3’ unilateral bulge of the D1-D1’ helix and sequence from position 1–15/69–90 (Figs. 6d), and the V3 helix sequence and structure (Figs. 9d).

Colony bright blue green or olive-green. Filaments long, with variation in width between young and mature trichomes (Figs. 13a), rarely singly or doubly false branched (Figs. 13a–b), rarely with more than one trichome sharing a common sheath (Fig. 13c), 2.3–4.0 μm wide. Sheath firm, usually attached to trichome, occasionally widened, rarely irregular and stratified (Fig. 13d), absent in immature filaments or hormogonia. Trichomes untapered, not or slightly constricted at distinctly visible crosswalls, with necridia (Figure 13c–d, f), with meristematic zones, 1.9–3.3 μm wide. Hormogonia short (Figs. 13e–f). Cells typically isodiametric, often shorter than wide especially in meristematic zones (Fig. 13f), slightly longer than wide in young trichomes (Fig. 13a–b), (1.3)–1.7–2.7 μm long. End cells rounded. D1-D1’ helix of the 16S–23S ITS region 91 nucleotides long having the basal 3’ side loop of 8 unpaired nucleotides (5’-CAUCCCAA-3’) opposed by a single adenine residue, with multiple internal loops at positions 14–15/69–70, 19–23/60–65, 26–27/56–57 and 32–33/50–51. Terminal loop with 4 nucleotides, with sequence 5’-GAAA-3’ (Fig. 6d). Box B helix is identical to P. convoluta with 36 nucleotides, bearing 6 nucleotides at terminal loop (Fig. 7c). No V2 helix present between tRNAAla and tRNAIle. V3 helix 110 nucleotides long, with one basal internal loop (5–6/101), with one unilateral bulge at position 12–14, several small internal loops at positions 23–27/88–89, 30–32/84–85, 35–36/79–81, 42–45/71–73 and 49–51/64–67. Terminal loop of 6 nucleotides, bearing sequence of 5’-GUAAUA-3’ (Fig. 9d).