Micrasterias torreyi var. pseudocurvata G.J.P.Ramos & C.W.N.Moura, 2019

Ramos, Geraldo José Peixoto, Costa, Fabiana De Matos, Santos, Maria Aparecida Dos & Moura, Carlos Wallace Do Nascimento, 2019, Taxonomic novelties, new records, and rare species of desmids from the Chapada Diamantina region, Brazil, Phytotaxa 391 (3), pp. 185-196 : 192-194

Micrasterias torreyi var. pseudocurvata G.J.P.Ramos & C.W.N.Moura , var. nov. ( Figs 55–57 )

Diagnosis— This variety is similar to var. curvata , differing from the latter by having more robust lobes, almost straight, with tiny spines of similar sizes.

Cell dimensions: length 290–300 μm, breadth 230–240 μm, apical lobe 40–50 μm, isthmus 50–60 μm.

Holotype: material numbered ( HUEFS 244150 !) deposited at Herbário da Universidade Estadual de Feira de Santana , population illustrated here in LM ( Figs 55–57 ).

Etymology: The epithet refers to similarity with Micrasterias torreyi var. curvata

Type locality and habitat characteristics: Collected at “Rio das Pedras”, Piatã, Bahia state, Brazil. Lat. 13° 05’ 48” S, Long. 41° 51’ 02” W. Sample collected by G. J. P.Ramos, C. W. N. Moura, F. M. Costa and M. A. Santos s/n ( HUEFS 244150 ) on 13 July 2017. Micrasterias torreyi var. pseudocurvata occurred in periphyton ; water temperature 19ºC, pH 7.2, conductivity 20 μS. cm-1, dissolved oxygen 7.3 mg.L- 1.

Notes: The discriminating features of Micrasterias torreyi var. pseudocurvata are certainly the presence of more robust lobes, slightly curved, with straight margins, and with tiny spines of equal sizes. The morphologically closest taxa, M. torreyi var. curvata Willi Krieg. (1939: 98) , has tapered lobes, and more curved and spines of unequal sizes. Those curved morphological expressions of Micrasterias apparently are typical of the tropical region (e.g., Micrasterias doveri var. africana Bourr. [1961: 337] ), although they have rarely been documented in floristic studies in Brazil. Micrasterias torreyi var. curvata , for example, has confirmed records only in the states of Mato Grosso ( Krieger 1939), São Paulo ( Bicudo & Sormus 1982), and Amazonas ( Krieger 1939, Melo et al. 2009).

Figures

FIGURES 51–65. Micrasterias jenneri var. semicirculare (51–54): ventral view (51–53), lateral view (54); Micrasterias torreyi var. pseudocurvata (55–57): ventral view (55), lateral view (56), semicell (57); Staurastrum serriforme (58–62): ventral view (58–60), apical view (61,62); Tetmemorus furcatus (63–65): ventral view (63, 64), lateral view (65). Scale bar 30 μm (51–57), 10 μm (58–65).