Euastrum groenbladii A.M. Scott & H. Croasdale

Costa, Fabiana De Matos, Ramos, Geraldo José Peixoto, Oliveira, Ivaniabatista, Bicudo, Carlos Eduardo De Mattos & Moura, Carlos Wallace Do Nascimento, 2018, Five new taxa and a new record of Euastrum (Desmidiaceae) from the Chapada Diamantina region, Bahia State, Brazil, Phytotaxa 372 (3), pp. 193-202 : 197

Euastrum groenbladii A.M. Scott & H. Croasdale in Scott et al. ( Figs. 10–14 )

Cells dimensions: 33– 33.9 μm long, 22.1–23 μm wide, polar lobe 12–12.5 μm wide, isthmus 7–8 μm wide.

Material examined: BRAZIL. Bahia: Andaraí, Collected at “Marimbus do Baiano”, Pantanal dos Marimbus (Baiano Lagoon), 12° 45’ 54.2”S, 41° 18’ 41.2”W. Sample collected by F. M. Costa, G. J. P. Ramos & C. W. N. Moura. ( HUEFS 241814, HUEFS 241815, HUEFS 241799).

Habitat: Periphyton; conductivity 0.08 (± 0.01 mS. cm-1); dissolved oxygen 8.2 (± 2.3 mg.L- 1); pH 7.1 (± 0.5); total dissolved solids 0.03 (± 0.01 ppt); water temperature 27.5 (± 0.6 ºC); water transparency 0.52 (± 0.20 m).

Geographic distribution in Brazil: Amazonas ( Scott et al. 1965).

Notes: — Euastrum groenbladii is morphologically similar to E. biocellatum Scott & Croasdale (1965: 31) , although the latter differs by having a retuse incision between the basal and apical lobes, two scrobicles and by not having a line of supra-isthmus granules ( Scott & Croasdale 1965: fig. 52).

All of the morphological characteristics observed using SEM were also observed under LM. Variations were observed in terms of the basal lobes (rounded to slightly truncate) and the apical incision (shallow to deep).

When compared the morphological features reported by Scott et al. (1965:33) with those from Bahia, the only difference is the number of scrobicles: the semicells from Amazonas has one scrobicle (fig. 62), whereas the Bahia specimens always have two scrobicles. Overall, Euastrum groenbladii is a rare species and the present record is the first for northeastern Brazil.

Figures

FIGURES 2–14. Euastrum abruptum var. chapadae var. nov.: LM (2–4); SEM (5), frontal view (2, 3, 5), lateral view (4). Euastrum fissum var. nordestinum var. nov.: LM (6–8); SEM (9). Euastrum groenbladii: LM (10–13); SEM (14), head of arrows indicating a line composed of supra-isthmal granules; frontal view (10, 11, 14), apical view (12), lateral view (13). Scale Bars: 10 μm.