Desmidium graciliceps (Nordstedt) Lagerheim var. graciliceps, Öfversigt Kongliga Svenska Vetensk-Akademiens Förhandlingar 42(7): 228. 1885.

Desmidium quadratum Nordstedt var. graciliceps Nordstedt in Wittrock & Nordstedt, Algae Exsiccatae 8: nº 367. 1880.

(Figs. 8 A-B)

Cells were about equal in length and width, 20-23 × 14- 22 μm broad, 6-7 μm broad at the apex and 13-14 μm broad at the isthmus. Semicells pyramidal-truncated; straight apical margins, truncated in the middle part; undulated lateral margins that were convergent to the semicell apex; rounded basal angles; shallow median constriction; open median sinus, which is linear or acute; hyaline to light brown cell wall; axial chloroplast.

Material examined: BRAZIL, AMAPÁ, Macapá, Curralinho Lake, 15.IV.2008, C.B. Araújo (SP469226), 15.VII.2008, C.B. Araújo (SP469228) .

Comments: the characteristic features of this species were the truncated semicells in their middle part, straight apical margins, and undulated lateral margins, which converge to the semicell apex. According to Oliveira (2011) and Bittencourt-Oliveira (1993b), Desmidium graciliceps (Nordstedt) Lagerheim is morphologically similar to Desmidium grevillii De Bary, but the latter differs in having relatively smaller cells and narrower apex.

Distribution in Brazil: Bahia (Förster 1964, Oliveira et al. 2010, Oliveira 2011); Mato Grosso (Borge 1925); Pará (Scott et al. 1965, Förster 1969); Paraná (Bittencourt-Oliveira 1993b); Rio Grande do Sul (Sophia et al. 2005); São Paulo (Bicudo 1969, Bicudo & Samanez 1984, 2016).