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 Drouetiella Mai, Johansen et Pietrasiak gen. nov. Description:— Filaments mostly solitary, at times consolidated into fascicles, with infrequent single false branching. Sheath clear, thin, and firm, occasionally widened. Trichomes untapered, straight, flexuous, or spirally coiled, but not in nodules, slightly constricted at the crosswalls. Cells mostly longer than wide, becoming isodiametric to slightly shorter than wide in dividing trichomes, without aerotopes, rarely with a central granule in the cytoplasm; with parietal thylakoids. Apical cells cylindrical, untapered, rounded, without calyptra. Reproduction by trichome fragmentation via disintegration without necridia. Etymology:— Drouetiella : named in honor of Francis Drouet, a prominent North American phycologist of the late 20 th century whose monographic works still serve as a primary bibliographic reference into the nomenclature of the cyanobacteria. Type species:— Drouetiella lurida (Gomont) Mai, Johansen et Pietrasiak comb. nov . Taxonomic notes:— The genus Drouetiella currently contains three named species: D. lurida , D. fasciculata , and D. hepatica . This genus is most closely related to the cluster containing both Cartusia and Pegethrix ( Fig. 2 ). Genetic identity analysis of the 16S rRNA of these species separated three species at the 98.8 % threshold ( Table 9 ). However, their percent dissimilarity in the ITS regions strongly supported their separation into four different lineages ( Table 10 ). There are also diagnosable differences among the species in their morphology ( Figs. 14‒16 ) and secondary structures of the ITS.