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 Author Mai, Truc Department of Biology, John Carroll University, 1 John Carroll Blvd., University Heights, Ohio 44118, USA & Department of Plant and Environmental Sciences, New Mexico State University, Skeen Hall Room N 127, P. O Box 30003 MSC 3 Q, Las Cruces, New Mexico 88003, USA. Author Johansen, Jeffrey R. Department of Biology, John Carroll University, 1 John Carroll Blvd., University Heights, Ohio 44118, USA & Department of Botany, Faculty of Science, University of South Bohemia, 31 Branišovská, 37005 České Budějovice, Czech Republic Author Pietrasiak, Nicole Department of Plant and Environmental Sciences, New Mexico State University, Skeen Hall Room N 127, P. O Box 30003 MSC 3 Q, Las Cruces, New Mexico 88003, USA. Author Bohunická, Markéta Author Martin, Michael P. Department of Biology, John Carroll University, 1 John Carroll Blvd., University Heights, Ohio 44118, USA text Phytotaxa 2018 2018-08-16 365 1 1 59 http://dx.doi.org/10.11646/phytotaxa.365.1.1 journal article 10.11646/phytotaxa.365.1.1 1179-3163 13704923 Pegethrix indistincta Mai, Johansen et Bohunická , sp. nov. Diagnosis: ―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 ). Description:— 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. FIGURE 12. Pegethrix convoluta . A. Consecutively false-branching filaments. B–C. Compact nodules formed by rapid cell division in local region of trichomes. D–E. Sheath rarely irregular and stratified, more commonly tightly attached to trichomes. F. Necridia abundant in mature trichomes. Scale bar 10μm in 1000X magnification. FIGURE 13. Pegethrix indistincta . A–B. Double and single-false branching filaments. C. Multiple trichomes coiling in one common sheath. D. Thick and firm sheath observed in mature trichomes. E–F. Hormogonia released from bundles of trichome undergoing rapid disintegration (note necridia). Scale bar 10μm in 1000X magnification. 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 ). Etymology:— indistinctus (L.): indistinct, without morphological apomorphies that distinguish it from the other species. 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 GSENM , Kane County, Utah , USA . Found in black compact microbial mat. Holotype here designated:— BRY 37774 !, Herbarium for Nonvascular Cryptogams, Monte L. , Bean Museum, Provo, Utah . Isotypes here designated: ― BRY 37775! and BRY 37776!, Herbarium for Nonvascular Cryptogams, Monte L., Bean Museum, Provo, Utah . Reference strain: ―GSE-TBC-7GA, Algal Culture Collection at John Carroll University, Cleveland, USA . Additional reference strains: GSE-TBC-7GB and GSE-TBD 1-7G, Algal Culture Collection at John Carroll University, Cleveland, USA .