Phymatodocis nordstedtiana var. nordstedtiana f. minor Börgesen, 1890

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 : 9-10

Phymatodocis nordstedtiana var. nordstedtiana f. minor Börgesen , Videnskabelige Meddelelser Dansk Naturhistorisk Forening 1890: 930 (sep. p. 25), text fig. p. 930. 1890.

( Figs. 19 A-B)

Cell 1.2 times longer than broad, 15-32 × 21-25 μm, and 11 μm wide at the isthmus. Semicells sub-rectangular; straight apical margins on each side; parallel lateral margins slightly straight or swollen in the mid region; moderate median constriction; linear median sinus, sometimes open at the proximal region; hyaline to light brown cell wall.

Material examined: BRAZIL, AMAPÁ, Macapá, Curralinho Lake , 03.VII.2007, C.B. Araújo (SP469218), 12.II.2008, C.B. Araújo (SP469224), 15.IV.2008, C.B. Araújo (SP469226) .

Comments: Phymatodocis nordstedtiana Wolle often presents some morphological variation, but the literature usually refers to two different forms: f. nordstedtiana ( Wolle 1884) and f. minor ( Börgesen 1890) .According to Croasdale et al. (1983), the “minor ” form somewhat resembles var. novizelandica Nordstedt (1887) . It is distinguished by a more or less prominent intumescence in the center of each semicell, which is rarely straight, presents very little convex, and is never upwardly convergent. From an apical view, the semicell of the “minor ” form has a rectangular and slightly convex lateral margin in the median region. Additionally, it is distinct from the f. nordstedtiana based on the smaller size of its cells. However, according to Bicudo & Samanez (2016), the difference in the size between the individuals of the typical form and the “minor ” form may sometimes lead to overlap.

Distribution in Brazil: Amazonas ( Souza 2008); Bahia ( Oliveira 2011); Pará (Förster 1969); Rio de Janeiro ( Sophia 1987); São Paulo (Borge 1918, Bicudo & Samanez 1984, 2016).

Figures

Figs. 16-23. Pseudofilamentous desmids of Curralinho Lake, Macapá,Amapá, Brazil. 16 A-B. Hyalotheca dissiliens var. dissiliens. A. fungi in the cell wall of the algae, B. detailed cells; 17 A-B. H. javanica. A. detailed pseudofilament, B. detailed cells; 18. Mateola curvata; 19 A-B. Phymatodocis nordstedtiana var. nordstedtiana f. minor. A. pseudofilament frontal view, B. pseudofilament lateral view; 20. Spondylosium desmidiiforme; 21. S. pulchrum var. pulchrum; 22. S. rectangulare var. rectangulare; 23 A-B. S. rectangulare var. goyazense, detailed cells and pseudofilaments. Scale bars = 10 µm.