Desmidium longatum Wolle

Araújo, Camila Barbosa de, Bicudo, Carlos Eduardo de Mattos, Takiyama, Luís Roberto & Melo, Sérgio de, 2020, Pseudofilamentous desmids (Zygnematophyceae) from an Amazonian floodplain lake (Macapá, AP, Brazil), Iheringia, Série Botânica (e 2020010) 75, pp. 1-14 : 6

Desmidium longatum Wolle , Desmids of the United States. 26, pl. 49, fig. 6. 1884.

Gymnozyga longata (Wolle) Nordstedt in Wittrock & Nordstedt, Algae Exsiccatae 15: nº 803. 1886.

( Figs. 10 A-C)

Cell 2.3 greater in length than width, 65-83 × 28-39 μm, 14-20 μm broad at the apex and 22-31 μm broad at the isthmus. Semicells pyramidal-truncate; straight apical margins; parallel lateral margins, slightly divergent to the apex; broad apex; broad to moderate truncated median constriction; conspicuous basal inflation on both sides of the isthmus; open to linear median sinus; 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), 15.IV.2008, C.B. Araújo (SP469226), 15.VII.2008, C.B. Araújo (SP469228) .

Comments: the present species resembles Bambusina brebissonii Kützing or Bambusina borreri (Ralfs) Cleve. However , D. longatum Wolle is different, as it presents twisted pseudofilaments, elliptic cells in an apical view, and cells larger than B. brebissonii . The specimens identified here are larger than the ones from North America, registered in Croasdale et al. (1983: 35-40 × 25-28 µm).

Distribution in Brazil: first record of this species in Brazil.

Figures

Figs. 3-15. Pseudofilamentous desmids of Curralinho Lake, Macapá, Amapá, Brazil. 3 A-C. Bambusina borreri. A, B. detailed cells; C. detailed pseudofilament; 4. B. borreri var. brasiliensis; 5 A-B. B. borreri var. majus, detailed cells and pseudofilaments; 6. Desmidium baileyi var. baileyi f. bailey; 7 A-B. D. elegans. A. detailed pseudofilament, B. detailed cell; 8 A-B. D. graciliceps var. graciliceps. A. frontal view of the pseudofilament, B. slight modification of the pseudofilament frontal view; 9. D. graciliceps var. groenbladii; 10 A-C. D. longatum. A. pseudofilament frontal view, B. formation of the elongate conjugation tube, C. zygospore; 11 A-B. D. quadratum var. quadratum. A. detailed pseudofilament, B. detailed cells; 12. D. quadratum var. constrictum; 13 A-B. Groenbladia neglecta var. neglecta. A. detailed pseudofilament, B. detailed cells; 14 A-B. G. neglecta var. elongata. A. detailed pseudofilament, B. detailed cells; 15. Haplozyga armata var. armata. Scale bars = 10 µm.