Komarkovaea angustata 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 : 44-46

Komarkovaea angustata Mai, Johansen et Pietrasiak sp. nov.

Diagnosis:— Phylogenetically closest to Tildeniella species, however, differing from that genus and all other genera in the Oculatellaceae by the basal unilateral bulge present in the Box-B helix ( Fig. 7o ).

Description:— Colony fasciculated, penetrating the agar, bright blue-green. Filaments lacking false branching, with variation in width between post-hormogonial and mature filaments, up to 3.9 μm wide ( Fig. 22a–d ). Sheath firm, thin, colorless, up to 0.7 μm wide. Trichomes constricted at cross-walls, rarely tapering ( Figs. 22d ), post-hormogonial trichomes 1.8–2.9 μm wide, mature trichomes 3.3–3.9 μm wide. Hormogonia ( Figs. 22a–b ) and necridia ( Figs. 22b–c ) present. Cells with parietal thylakoids, with up to 3 small granules per cell, sometimes with one small orange granule ( Fig. 22e , at arrows), commonly cylindrical, especially in young trichomes, becoming isodiametric in actively growing trichomes; in more mature trichomes cells barrel-shaped, and pancake-like in meristematic zones ( Fig. 22c–d ), 2.2–5.7 μm long.

D1-D1’ helix 63 ncleotides long, with basal 3’ unilateral bulge 7 nucleotides long (5’-CAUCCUA-3’), with one C/U mismatch at position 9/48, one unpaired Adenine residue at position 15 of the 5’ strand, and one large internal loop at position 21–23/33–37 immediately separated from the terminal loop by a 5’-GG:CC-3’ clamp. Terminal loop sequence 5’-ACAGU-3’ ( Fig. 6p ). Box B helix 41 nucleotides long, with one distinctive basal 3’ unilateral bulge at position 5/32–37, one internal loop at position 10–11/26–27; terminal loop with sequence 5’-AAUC-3’ ( Fig. 7o ). V2 helix 20 nucleotides long, with terminal loop of 4 nucleotides ( Fig. 8k ). V3 helix 87 nucleotides long, with multiple mismatches at position 13/77, 19/71, an unpaired adenine residue at position 9 on the 5’ strand, and three internal loops at position 5–6/83, 23–24/66–67 and 30–31/58–60 ( Fig. 9m ).

Etymology:— angustatus (L.): narrowed, referring to the trichomes which are occasionally narrowed towards the end, as well as the narrowed hormogonia.

Type locality:— Puerto Rico, El Yunque National Forest: Waterfall in the forest, 18°27.811’ N – 66°7.005’W collected in 2012 by Jay Hillery.

Holotype here designated:— Holotype BRY37783 !, Herbarium for Nonvascular Cryptogams, Monte L. Bean Museum, Provo, Utah .

Reference strain: ―EY1- AM 2, Algal Culture Collection at John Carroll University, Cleveland, USA.

Taxonomic notes:— This genus is character-poor. The heterogeneity in trichome width and absence of false branches is characteristic, and could be compared to tapering species in Leptolyngbya : L. tenuis ( Gomont 1892: 169) Anagnostidis & Komárek (1988: 393) , L. laminosa ( Gomont 1892: 167) Anagnostidis & Komárek (1988: 392) and L. fragilis ( Gomont 1892: 163) Anagnostidis & Komárek (1988: 391) . However, in every comparison the trichomes of K. angustata are wider. The species has low 16S rRNA gene sequence identity with the other genera in the Oculatellaceae (91.9-93.5%, see Table 5), strong evidence that it represents a separate genus-level lineage.

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 22. Komarkovaea angustata. A–B. Variation in trichome width between mature and young filament or hormogonia. C. Variation in cell shapes between young and mature trichomes: isodiametric, slightly longer than width or barrel-shaped, and abundance of necridia in mature trichomes. D. Rapid regional cell division along trichomes resulting in basal and apical parts of filaments. E. Reddish small granules occassionaly observed on cells. Scale bar 10μm in 1000X magnification.