Taxonomic notes on some Cosmarium species (Desmidiaceae, Zygnematophyceae) from Brazil Author Ramos, Geraldo José Peixoto 0000-0003-2089-0461 Programa de Pós-Graduação em Botânica, Universidade Estadual de Feira de Santana, Av. Transnordestina, s / nº, Novo Horizonte, 44036 - 900, Feira de Santana, BA, Brazil. & geraldojpr @ gmail. com; https: // orcid. org / 0000 - 0003 - 2089 - 0461 geraldojpr@gmail.com Author Santos, Maria Aparecida Dos 0000-0001-9354-7192 Programa de Pós-Graduação em Botânica, Universidade Estadual de Feira de Santana, Av. Transnordestina, s / nº, Novo Horizonte, 44036 - 900, Feira de Santana, BA, Brazil. & maria. asbio @ hotmail. com; https: // orcid. org / 0000 - 0001 - 9354 - 7192 maria.asbio@hotmail.com Author Moura, Carlos Wallace Do Nascimento 0000-0001-6904-6603 Programa de Pós-Graduação em Botânica, Universidade Estadual de Feira de Santana, Av. Transnordestina, s / nº, Novo Horizonte, 44036 - 900, Feira de Santana, BA, Brazil. & wallace @ uefs. br; https: // orcid. org / 0000 - 0001 - 6904 - 6603 wallace@uefs.br text Phytotaxa 2021 2021-02-12 483 3 291 299 http://dx.doi.org/10.11646/phytotaxa.483.3.9 journal article 10.11646/phytotaxa.483.3.9 1179-3163 5420996 Cosmarium pygmaeum W.Archer ( Fig. 5 , 33–38 ) Cell dimensions: length 7–8 μm, breadth 8,5–9 μm, breadth of isthmus 3–3,5 μm. Material examined :— BRAZIL . Pantanal dos Marimbus, Andaraí, Bahia State . Samples: HUEFS 253745, HUEFS 253766 Habitat :—This species was found associated with periphyton of Utricularia foliosa and Cabomba caroliniana . EC 0.02 (± 0.01 mS cm-1 ), DO 6.3 (± 0.3 mg L- 1 ), pH 7.5 (± 0.8), TDS 0.01 (± 0.005), T 29.8 (± 1.8 ºC), WT 0.6 (± 0.18m ) Note :— Cosmarium pygmaeum is a species with cosmopolitan distribution, with a bunch of records mainly in Europe ( Guiry & Guiry 2020 ). However, in Brazil and even in South America, this species is rarely reported in the literature. There is only a record of its occurrence in the Brazilian territory, which was based on the sample gathered in municipality of Rio Claro, State of São Paulo (Bicudo 1969, Bicudo et al. 2019 ). Thus, the material from Bahia represents the second record of that species in Brazil . Overall, it is one of the most polymorphic and smaller Cosmarium taxa occurring in the Marimbus. The main morphological variations in the specimens from Bahia are the sinus, from open to closed, the central granule which can be next to the apical margin or close to the isthmus, and the papillae at the basal angles, which could be more or less projected ( Fig. 5 ). According to Kouwets (1987) the arrangement of granules on the cell wall is very variable, and without any taxonomic value.