Cosmarium elegantissimum Lundell (1871:53)

Ramos, Geraldo José Peixoto, Bicudo, Carlos Eduardo De Mattos & Moura, Carlos Wallace Do Nascimento, 2018, Some new, rare and interesting desmids from bromeliad phytotelmata in Brazil, Phytotaxa 346 (1), pp. 59-77 : 63

* Cosmarium elegantissimum Lundell (1871:53) ( Figs 14–19 )

Cell dimensions: 80–100 μm length, 25–40 μm width, 22–34 μm isthmus.

Material examined: BRAZIL, Bahia, Santa Teresinha, Serra da Jiboia. 14-I-2015, G. J. P. Ramos et al. s/n ( HUEFS 224656), 18-VII-2015, G. J. P. Ramos et al. s/n ( HUEFS 224682), 11-IX-2015, G. J. P. Ramos et al. s/n ( HUEFS 224698), 20-XI-2015, G. J. P. Ramos et al. s/n ( HUEFS 224716)

Habitat: bromeliad tanks ( Alcantarea nahoumii ); T 27.3 (± 3.0 ºC). pH 6.0 (± 0.5). C 0.25 (± 0.16 mS. cm-1). TDS 0.13 (± 0.10 ppt). DO 6.9 (± 2.8 mg.L- 1).

Notes: Morphologically, Cosmarium elegantissimum resembles C. pseudamoenum Wille ; the latter species differs, however, by having irregularly arranged granules, cells subcircular-elliptic in apical view, and smaller cell dimensions. During our analyses we observed some morphological variations in which the semicells were less elongated and had finer granules ( Figs 17–18 ) similar to Cosmarium simplicius (West & G.S.West) Grönblad (1931: 7) , which had previously been considered a variety of Cosmarium elegantissimum by West & West (1908). That morphotype was often associated with C. elegantissimum in samples from Serra da Jiboia, showing intermediate features between them. We therefore consider that variation as an example of the phenotypic plasticity of C. elegantissimum in populations from Serra da Jiboia. Further studies will be needed to verify the relationship between C. elegantissimum and C. simplicius .

Figures

FIGURES 1–25. Closterium cornu var. minus LM (1, 2); Cosmarium amoenum var. jiboensis: LM (3–6); SEM (7–8), ventral view (3–4, 7), lateral view (44) apical view (46–48) and detail of cell wall with granules surrounded by pores; C. bahianum: LM (9–12); SEM (13), ventral view (9–10, 13), lateral view (11) apical view (12); C. elegantissimum: LM (14–16); SEM (19), ventral view (14–15, 17–19), apical view (16); C. scrobiculosum: LM (20–23); SEM (24–25), ventral view (20–21, 25), lateral view (22) apical view (23–24). Scale bar 10 μm (1–7, 9–24), 5 μm (8, 25).