Drouetiella fasciculata Mai, Johansen et Bohunická, 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 : 32-33

Drouetiella fasciculata Mai, Johansen et Bohunická sp. nov.

Diagnosis: ― D.fasciculata is phenotypically distinct from other Drouetiella species due to its bright blue-green color and fasciculation of trichomes. The V3 helix has identical sequence and structure to D. hepatica in nucleotides 1–8 on the 5’ strand and their complement on the 3’ strand ( Fig. 8e ); however, in general it is distinctive in length and sequence from all other species ( Table 6). The percent dissimilarity between the ITS region of this species and the other taxa is>25% ( Table 10).

Description:— Colony bright blue green, composed of fasciculated ( Fig. 15a ) and solitary filaments, growing into the agar. Filaments long, without false branching, frequently slightly coiled and entangled ( Figs. 15b–c ), 2.7– 3.2 μm wide. Sheath firm, usually attached to trichome, occasionally distinct, clear, up to 1.3 μm wide. Trichomes not constricted at the cross-walls, with necridia, lacking meristematic zones, with cell division occurring throughout trichome, 1.5–2.4 (3.0) μm wide. Hormogonia rare ( Fig. 15d ). Cells longer than wide, occasionally isodiametric after division, with peripheral thylakoids, with one large or two smaller central granules, 3.1–4.4 (5.4) μm long ( Figs. 15e–f ). End cells untapered, rounded ( Fig. 15g ).

D1-D1’ 65 nucleotides long, with a 3’ unilateral bulge of 7 nucleotides (5’-CAACCCA-3’), and several internal loops in the mid-helix region at positions 8–9/49–50 and 15–16/43–44, with the largest bilateral bulge at position 21–24/34–38 immediately subtending the terminal loop by a 5’-GC:GC-3’ clamp ( Fig. 6h ). Box B helix 39 nucleotides long, with a basal bulge at position 5/34–35 and one unpaired adenine residue at position 9 on the 5’ strand ( Fig. 7g ). V2 helix 11 nucleotides long, with a 5-nucleotide terminal loop, having sequence 5’-AAUAU-3’ ( Fig. 8e ). V3 helix 51 nucleotides long, with one basal unpaired guanine residue at position 46 of the 3’ strand, and one large bilateral bulge at position 9–12/39–42. Terminal loop sequence 5’-UUGC-3’ ( Fig. 9h ).

Etymology:— fasciculatus (L.): fasciculate, referring to the ability of this species to form fascicle of trichomes.

Type locality: ―Lower Calf Creek Falls site, in the 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, found in mats with filamentous algae, in the GSENM, Kane County, Utah, USA.

Holotype here designated:— BRY37779 !, Herbarium for Nonvascular Cryptogams, Monte L., Bean Museum, Provo, Utah.

Reference strain: ―GSE-PSE-MK29-07A, Algal Culture Collection at John Carroll University, Cleveland, USA.

Taxonomic notes:— The simple morphology of D. fasciculata keys to multiple species of Leptolyngbya . The subaerophytic species, Leptolyngbya gracillima ( Hansgirg 1892b: 41) Anagnostidis & Komárek (1988: 391) is similar in dimensions, but differs in the possession of false branching. Leptolyngbya lagerheimii (Gomont ex Gomont 1892: 147) Anagnostidis & Komárek (1988: 391) is similar but was described from stagnant waters in a tropical climate ( Brazil). Leptolyngbya subtruncata ( Woronichin 1930: 69) Anagnostidis (2001: 368) was close to D. fasciculata in size of cells, but was described as having truncate apical cells. L. subtruncata is an incompletely described species, and is sufficiently ecologically different from D. fasciculata that we do not feel using this name is appropriate for our populations. Several other species were also described to have similar morphology, especially the irregular coils, including Leptolyngbya fritschii Anagnostidis (2001: 366) , Leptolyngbya mucosa ( Gardner 1927: 43) Anagnostidis & Komárek (1988: 392) , Leptolyngbya patinae ( Schwabe 1944: 180) Anagnostidis (2001: 367) , Leptolyngbya spiralis (C.-C. Jao 1948: 169) Anagnostidis (2001: 367), and Lyngbya jacutica Kisselev (1935:73) . These five species were described from tropical, marine, or polar aquatic habitats very different from the temperate climate, subaerophytic habitat in which D. fasciculata was found. Furthermore, they differ in dimensions, and it appears to be a new species. It is equally morphologically dissimilar to these species, such that it could not be assigned to any one of them with confidence.

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 15. Drouetiella fasciculata. A. Fasiculated filaments with individual sheath. B. Mature trichomes with one to two large central granules. B–C. Different coiling patterns of filaments. D. Hormogonia. E–G. Cells barrel-shaped, not constricted and separated by somewhat translucent cross-walls. Scale bar 10μm in 400X (A) and 1000X magnification (B–J).