Groenbladia neglecta (Raciborski) Teiling var. elongata Scott & Grönblad, Acta Societatis Scientiarum Fennica: nov. ser. B, 2(8): 48, pl. 35, fig. 17-25. 1957.

(Figs. 14 A-B)

Cells 4-5 times greater in length than width, 44-84 × 7-15 μm, 6-13 μm broad at the apex. Semicells cylindrical; broadly truncated apical margins; parallel lateral margins; subquadrate angles; shallow and broad median constriction; median sinus with a small invagination; hyaline cell wall; axial chloroplast.

Material examined: BRAZIL, AMAPÁ, Macapá, Curralinho Lake, 02.VI.2007, C.B. Araújo (SP469217), 03.VII.2007, C.B. Araújo (SP469218), 14.I.2008, C.B. Araújo (SP469223), 12.II.2008, C.B. Araújo (SP469224), 15. IV.2008, C.B. Araújo (SP469226), 13.V.2008, C.B. Araújo (SP469227), 15.VII.2008, C.B. Araújo (SP469228) .

Comments: this variety differs from the typically observed characteristics of the species, as it presents longer cells and a median sinus with a small invagination.

Distribution in Brazil: Amazonas (Förster 1974, Souza 2008, Souza & Melo 2010); Bahia (Oliveira et al. 2010); Pará (Scott et al. 1965, Förster 1969).