Desmidium graciliceps (Nordstedt) Lagerheim var. graciliceps

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 : 5

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).

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.