3. Pleurotaenium subcoronulatum f. longior Huber-Pestalozzi 1930: 468, no fig. Type locality: Union of South Africa [currently Republic of South Africa], Knysna Forest, near Harkerville, a shallow swamp about 30 m in diameter, slightly brownish water, hydrophytes, leg. G. Huber-Pestalozzi, 7 October 1926. Description: Cells of P. subcoronulatum f. longior are approximately 600 μm in length and 33.8 μm wide (middle) and the apex is approximatly 36 μm wide. These dimensions are much longer and slightly wider than those described for the type species by Turner (1893) (compare Table 1). In P. subcoronulatum f. longior 20-22 tubercles surrounding the apex are described. Chain formation, consisting of 2–4 cells attached to each other, was observed. Distribution: Africa: South Africa (Huber-Pestalozzi 1930). Note: Krieger (1937) included Pleurotaenium subcoronulatum f. longior in the nominate variety as synonym. In our opinion this form is morphologically different due to the much longer cells (in 1.5-2 times) and much narrower apex (about 0.7 times) and must stay separately from type one.

Published as part of Levanets, Anatoliy & Vuuren, Sanet Janse Van, 2024, New insights into the morphology, taxonomy and geographical distribution of Pleurotaenium subcoronulatum (Zygnematophyceae, Desmidiales), pp. 144-158 in Phytotaxa 655 (2) on pages 150-151, DOI: 10.11646/phytotaxa.655.2.3, http://zenodo.org/record/13212948