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.
Differing from other species in the genus based on the frequent formation of loose irregular nodules. Distinguishable from P. indistincta in the cytosine residue opposite the basal 3’ unilateral bulge of the D1-D1’ helix (Figs. 6c, d) and the V3 helix sequence and structure (Figs. 9c, d). Some similarity with P. bostrychoides and P. olivacea in nucleotides 1–15 on the 5’ strand and their complement was observed, but the absence of the V2 helix and other dissimilarities clearly set them apart.
Colony bright blue green, radially spreading, growing into the agar. Filaments fasciculated, long, sometimes singly or doubly false branched (Fig. 12a), straight or slightly bent (Figs. 12a–b, e), frequently forming loose to compact nodules (Figs. 12b–c), 1.4–3.9–(4.9) μm wide. Sheath firm, colorless, usually attached to trichome (Fig. 12e), occasionally widened (Figs. 12d–e), rarely irregular and stratified, up to 1.3 μm wide. Trichomes untapered, not or slightly constricted at distinctly visible cross-walls, with necridia (Figs. 12b, e–f), lacking meristematic zones, with cell division occurring throughout trichome, 1.3–2.5 (3.2) μm wide. Hormogonia few-celled (Fig. 12a). Cells slightly shorter than wide to longer than wide, sometimes with a single central granule, with parietal thylakoids, 1.0–2.5–(3.7) μm long. End cells rounded. D1-D1’ helix of the 16S–23S ITS region 91 nucleotides long, with basal 3’ side loop of 9 unpaired nucleotides (5’-ACAUCCCAA-3’) opposed by a single cytosine residue, with multiple small internal loops at position 14–15/69–70 (with sequence 5’-AG/GA-3’), at 26–27/56–57 and 32–33/50–51, one large asymmetrical internal loop at position 19–23/60–65. Terminal loop with 4 nucleotides, with sequence 5’-GAGA-3’ (Fig. 6c). No V2 helix present between tRNAAla and tRNAIle. Box B helix with 36 nucleotides, bearing 6 nucleotides at terminal loop (Fig. 7c). V3 helix 110 nucleotides long, with one basal internal loop (5–6/101), one unilateral bulge at positions 12–14, several small internal
loops at positions 27–29/81–83, 32–33/76–77, 39–41/68–71 and 45–48/61–64 and a pair of mismatched 5’-U/C-3’ at position 36/74. Terminal loop of 6 nucleotides, having sequences 5’-GUAAAA-3’
