Cosmarium quadriverrucosum var. supraornatum Skuja ** (Fig. 2M) Nova Acta Regiae Societatis Scientiarum Upsaliensis, serie 4, 14 (5): 139 (Skuja 1949). DISTRIBUTION. — Brazil, Myanmar, China, Australia, and New Zealand. Amazon Basin: no records. Western Amazonia (lowlands): no records. DeScRiPTiON Cells 5.9 µm long, 25.4 µm wide, isthmus 9.0 µm; cells as long as wide. Cells with deep median constriction, closed median sinus, straight; subcircular semicells; apical margin straight to broadly rounded; central tumor with warts on the face of the semicell, a variable number of warts in rows around the semicell, without any arrangement; axial chloroplast; two pyrenoids. REMARKS This taxon is small and is recognized from the type variety by having a more wavy, irregular cell outline which is given by the presence of more warts. Compared with Cosmarium furcatospermum West & G.S.West, C. quadriverrucosum var. supraornatum has two pyrenoids instead of one. Our specimens are morphologically similar and within size range shown for this taxon in the original description by Skuja (1949) and those reported by Oliveira de et al. (2010) for Brazil and Dingley (2001) for Australia.

Published as part of SÁNCHEZ, Luzmila, SÁNCHEZ, Fernando R., RÍOS-TOUMA, Blanca & José V. MONTOYA, 2025, Desmidiales (Desmidiaceae, Zygnematophyceae) from lowland rivers and floodplain lakes of Ecuadorian Amazonia, pp. 31-60 in Cryptogamie, Algologie 20 (3) on page 40, DOI: 10.5252/cryptogamie-algologie2025v46a3, http://zenodo.org/record/17108984