Pleurotaenium subcoronulatum var. detum

Levanets, Anatoliy & Vuuren, Sanet Janse Van, 2024, New insights into the morphology, taxonomy and geographical distribution of Pleurotaenium subcoronulatum (Zygnematophyceae, Desmidiales), Phytotaxa 655 (2), pp. 144-158 : 151-152

6. Pleurotaenium subcoronulatum var. detum West & G.S. West 1896: 235, pl. 13: figs 2, 3

Type locality: USA.

Description: The apices of the semicells are dilated and a clear abrupt constriction is situated at a distance of approximately one seventh of the semicell length from the pole ( Fig. 4E ). The cell wall is very slightly undulated beyond the basal inflation. The number of tubercles ranges from 26–30. The cells are about 11–19 times longer than wide. Cells are 404–446 µm long, and 29–38 µm wide at the base of the semicell. The apex is 27–28 µm wide, while the width at the constriction is 20–27 µm.

Distribution:

North America: Canada (Irénée-Marie 1939; Poulin et al. 1995), USA ( West & West 1896; Smith 1924; Brown 1930; Prescott et al. 1975; Dillard 1990; Akin & Meyer 1996; Marshall et al. 2005; Laderman & Domozych 2005; Smith 2010).

Central America: Cuba ( Comas 2009).

South America: Argentina ( Tell 1985), Brazil ( Bicudo & Ungaretti 1986; Souza 2008).

Africa: Democratic Republic of the Congo ( Van Oye 1953; Golama Swana Kaketa 1996), Guinea ( Bourrelly 1975), Mozambique ( Rino 1972); Sierra Leone ( Grönblad et al. 1968); Uganda ( Grönblad et al. 1964); Zimbabwe ( Rich 1935). Lakes on borders of African countries: Tanganyika, Victoria ( Cocquyt et al. 1993).

Asia: Japan ( Hirose et al. 1977), Russian Federation ( Medvedeva 2023).

Australia and New Zealand: Australia ( Day et al. 1995).

Figures

FIGURE 4. Comparison of the morphology of P. subcoronulatum with closely related infraspecific taxa. A) P. subcoronulatum (from Turner 1893), B) P. subcoronulatum (from West & West 1895, C) P. subcoronulatum f. elongatum (from Prescott et al. 1975), D) P. subcoronulatum var. africanum (from Krieger 1937), E) P. subcoronulatum var. detum (from West & West 1896), F) P. subcoronulatum var. maximum (from Van Oye 1953), G) P. subcoronulatum var. rectum (from Borge 1903) and H) P. subcoronulatum var. spinulosum (from Opute 2000). No scale bars; dimensions indicated in descriptions.