Desmodesmus abundans (Kirchner) E.H.Hegewald

Burgel, G., Ribas, P. G., Ferreira, P. C., Passos, M. F., Santos, B., Savi, D. C., Ludwig, T. A. V., Vargas, J. V. C., Galli-Terasawa, L. V. & Kava, V. M., 2022, Morphology, molecular phylogeny and biomass evaluation of Desmodesmus abundans (Scenedesmaceae-Chlorophyceae) from Brazil, Brazilian Journal of Biology (e 265235) 82, pp. 1-11 : 5-7

Desmodesmus abundans (Kirchner) E.H.Hegewald

Algological Studies, v. 96, p. 1, 2000.

Solitary cells elliptical. Coenobia with 2 to 4 cells arranged linearly.Cells elliptical, rounded poles, 5.2–6.2 Μm long and 1.5–4 Μm wide. Coenobia and solitary cells with one spine at each pole (see Figure 3A, 3C, 3D, 3F ) and few short spines. Two celled colonies with 4 to 6 short spines irregularly distributed on the cell surface (see Figure 3B, 3E ). Cell walls smooth with longitudinal ridges and one or two chimney-like rosettes per cell (see Figure 3D ). Chloroplast parietal, with single pyrenoid.

The population studied here is morphologically similar to D. abundans morphotype IIIa presented by Hegewald and Schnepf (1991), differing by the shorter cell length of our specimens (5.2–6.2 Μm), compared to D. abundans morphotype IIIa (7–9.2 Μm). However, according to Hegewald and Schnepf (1991), D. abundans morphotypes include cells with smaller length (4.5–38 Μm), thus admitting our population in the species.

Desmodesmus abundans morphologically resembles D. spinosus and D. subspicatus . However, D. abundans differs by having a longitudinal ridge, one or two chimney-like rosettes per cell, and smaller measures of cell length and width. D. spinosus has a median spine on the outer cells of the coenobia, beyond the apical ones. In addition, on the internal cells lateral spines are arranged in series and may or may not have apical spines on the coenobia. D. subspicatus , a species very similar to D. spinosus , is distinguished by one or two simple rosettes decorating each cell ( Hindak, 1990).

Morphological comparison between Desmodesmus abundans -like species was presented in Table 2.

The obtained ITS sequence of D. abundans LGMM 0013 (GenBank accession number: ON191015) was used for phylogenetic analysis. Based on the phylogenetic tree, using sequences of ITS region of Desmodesmus species (see Figure 4 ), the D. abundans LGMM 0013 strain is closely related to D. abundans , D. spinosus and D. asymetricus species, corroborating with the morphological data.

DesmodesmUs aBUndans high biomass productivity

Figures

Figure 3. Morphology of D. abundans LGMM0013 by optical microscopy (A-C) and scanning electron microscopy (D-F). From A to C scale bar (black) equivalent to 10 Μm. A: single cell. B: Coenobium with two cells. C: Coenobium with four cells. From D to F scale bar equivalent to 5 Μm.D: Single-cell, presence of spines and tubes. E: Coenobium with two cells, presence of thorns. F: Coenobium with four cells, presence of spines and tubes. Black arrow: chimney-like rosettes; white arrow: longitudinal ridges.

Figure 4. Phylogenetic analysis of Desmodesmus species by Bayesian inference using ITS sequences. Posteriori probability values are left from nodes.