Cosmarium scrobiculosum Borge (1903:87)

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 : 65

Cosmarium scrobiculosum Borge (1903:87) ( Figs 20–25 )

Cells 1.7 times longer than wide, deep median constriction, closed sinus linear, slightly dilated next to isthmus,; semicells subreniform, with rounded basal angles, convex lateral margins, rounded apical angles, margins granularundulate; cell wall scrobiculate with granules arranged in vertical series between scrobicules, 1 pore in each scrobicule (SEM view); in lateral view semicells subcircular, in apical broadly elliptic; chloroplast with 2 pyrenoids; cells (65–) 70–85μm long, 45–50 μm wide, 45–50 μm isthmus.

Material examined: BRAZIL, Bahia, Santa Teresinha, Serra da Jiboia. 14-I-2015, G. J. P. Ramos et al. s/n ( HUEFS 224666), 18-VII-2015, G. J. P. Ramos et al. s/n ( HUEFS 224678), 11-IX-2015, G. J. P. Ramos et al. s/n ( HUEFS 224699), 20-XI-2015, G. J. P. Ramos et al. s/n ( HUEFS 224718)

Habitat: bromeliad tanks ( Alcantarea nahoumii ); T 27.3 (± 2.7 ºC). pH 5.9 (± 0.5). C 0.24 (± 0.17 mS. cm-1). TDS 0.12 (± 0.08 ppt). DO 7.9 (± 4.0 mg.L- 1).

Notes: This taxon was previously known for this area as Cosmarium logiense Bissett (1884:194) ( Ramos et al. 2011), however after a detailed reanalysis of the material including SEM observations, we decided to reidentify it as C. scrobiculosum . The confusion between these taxa is common in some floristic studies in Brazil. The specimens identified as C. logiense by Oliveira (2011) and Biolo (2016), probably, refer to C. scrobiculosum . In Brazil, there are records of this species in north region ( Grönblad 1945, Thomasson 1977), southeast ( Borge 1918) and midwest ( Borge 1903).

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).