Drouetiella sp.

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

Drouetiella sp. ANT.LH52.2 ( Figs. 6g , 7f , 8d , 9g )

Molecular Diagnosis: ―Secondary structures of conserved domain of the ITS are very similar to D. hepatica , almost identical in shape but with considerable difference in sequences ( Figs. 6g , 7f , 8d , 9f ), separated from D. hepatica by the extremely different habitats. Similar to other species in the presence of a 5’-GC:GC-3’ closing pairs immediate to the terminal loop in the D1-D1’ stem ( Fig. 6g ), and position 1–14 of the 5’ strand and its 3’ complementary of the Box B structure ( Fig. 7f ), but is variously different in other characteristics.

Molecular Description:— D1-D1’stem 64 nucleotides long, with basal 3’ unilateral bulge of 7 unpaired nucleotides (5’-CAUCCCA-3’). Mid-helix region with one small internal loop at position 24/34–35 immediately separated from the terminal loop by a 5’-GC:GC-3’ clamp, and two mismatches at position 9 (U/U) and 21 (G/A) on 5’ strand. Terminal loop having sequence 5’-AAUCA-3’ ( Fig. 6g ). Box B helix 34 nucleotides long, with one basal internal loop at position 5/29–30 and one unpaired adenine residue at position 9 of the 5’ strand ( Fig. 7f ). V2 helix 21 nucleotides long, almost identical to D. hepatica , terminal loop of 5 nucleotides with sequence 5’-AUUUU-3’ ( Fig. 8d ). V3 structure 52 nucleotides long, with one large internal loop at position 11–13/40–42 and one mismatch at position 6 (A/G) of the 5’ strand. Terminal loop sequence 5’-UAAG-3’ ( Fig. 9g ).

Reference strain: ― Leptolyngbya frigida ANT.LH 52.2.

Taxonomic notes:— This species of Drouetiella was isolated from an Antarctic environment without morphological description, and was identified on the basis of molecular characteristics only. Its original strain designation is Leptolyngbya frigida ANT.LH 52.2, but it certainly does not belong to Leptolyngbya . Other Antarctic strains designated as L. frigida (ANT.LH70.1, ANT.LMA.1) are phylogenetically placed in Pegethrix ( Fig. 2 ), so the correct placement of the species epithet frigida is ambiguous at this time. If the holotype specimen of L. frigida could be sequenced, it is possbile that it could be confirmed to belong in either Pegethrix or Drouetiella .

Figures

FIGURE 2. 16S rRNA Bayesian Inference analysis of the filamentous group of Synechococcales cyanobacteria, showing Oculatellaceae. Black polygons represent genera that have been validly described or are named in provision (e.g., “Trichotorquatus”), with length corresponding to the distance from the most basal OTU to the most diverged OTU of the genus. Posterior probabilities for the BI analysis are given above the nodes. Taxa which we consider to be incorrectly named in NCBI or requiring revisionary work are in quotation marks.

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.