Phormidium ( Kützing 1843: 190 ) Gomont (1892: 156)

Cunha De Oliveira, Elane D., Da Cunha, Alan C., Da Silva, Natalina B., Castelo-Branco, Raquel, Morais, João, Schneider, Maria Paula C., Faustino, Silvia M. M., Ramos, Vitor & Vasconcelos, Vitor, 2019, Morphological and molecular characterization of cyanobacterial isolates from the mouth of the Amazon River, Phytotaxa 387 (4), pp. 269-288 : 278

Phormidium ( Kützing 1843: 190) Gomont (1892: 156) ( Fig. 2E )

Strains:— LEGE 15488 (MF629805)

Description:— In culture, dark-green groups of filaments grow in fascicles all over the flask walls and at the interface between the air and the culture medium. The strain produces air bubbles that are visible at the bottoms of culture flasks. Trichomes are long, olive-green to dark-green. The trichomes are isopolar, straight to curved or even coiled, immotile, non-constricted or slightly constricted at the cross-walls, non-attenuated at their ends, and have necridia and facultative sheaths ( Fig. 2E ). The cells are wider (5.6–8.8 μm) than long (1.7–3.8 μm) and have granules.

Phylogeny and polyphasic identification:— The 16S rRNA gene sequence of LEGE 15488 shares 98% identity with the sequences of three strains identified as Phormidium , Lyngbya Agardh ex Gomont (1892: 118) and with an unidentified cyanobacterium ( Table S1). The sequence of LEGE 15488 ( Table 4) shows higher similarity values with the sequences from the strains Phormidium sp. LEGE 05292 (98.2%) and Lyngbya JW-2010b (98.1%), and to a less degree with that of Phormidium irriguum (Kützing ex Gomont) Anagnostidis & Komárek (1988: 405) CCALA 759 (96.9%). As shown in Fig. 3 , LEGE 15488 is placed in a robust clade (ML/BI/MP = 100/1.00/100) with the strain P. irriguum CCALA 759, at the base of the clade, which is an isolate that was proposed as epitype for this species and also for the genus ( Sciuto et al. 2012). Based on the polyphasic evaluation of LEGE 15488, this strain was identified as Phormidium sp. ( Komárek & Anagnostidis, 2005, Sciuto et al. 2012).

Figures

FIGURE 2 Microphotographs of the Amazonian cyanobacterial strains: A) Alkalinema aff. pantanalense LEGE 15484, B) Limnothrix cf. planctonica LEGE 15485, C) Leptolyngbya boryana LEGE 15486, D) Cephalothrix lacustris LEGE 15487, E) Phormidium sp. LEGE 15488, F) Pseudanabaena cf. galeata LEGE 15489, G) P. cf. galeata LEGE 15490, H) P. cf. galeata LEGE 15491, I) Cephalothrix lacustris LEGE 15492, J) C. lacustris LEGE 15493; K) unidentified Nostocales LEGE 15494, L) unidentified Nostocales LEGE 15495, M) unidentified Nostocales LEGE 15496, and N) Limnothrix cf. planctonica LEGE 15497.

FIGURE 3. ML phylogenetic tree based on 16S rRNA gene sequences showing the placement of the Amazonian cyanobacterial strains (in bold). Bootstrap values>70% or Posterior Probabilities>0.90 are indicated below the clade nodes (ML/BI/MP). Each strain sequence is identified by its accession number. The tree was rooted with the outgroup Chloroflexus aurantiacus J-10-fl (NR_074263), which was pruned from the tree for clarity. (T)refers to type strains according to CyanoType (Ramos et al. 2017).