Closterium lunula var. nordstedtii G.J.P.Ramos, C.E.M.Bicudo & C.W.N.Moura, 2022

Ramos, Geraldo José Peixoto, 2022, Nomenclatural and taxonomic notes on Brazilian desmids IV, Notulae Algarum 224, pp. 1-7 : 4

Closterium lunula var. nordstedtii G.J.P.Ramos, C.E.M.Bicudo & C.W.N.Moura , nom. nov.

Replaced name: Closterium lunula var. giganteum (Nordstedt) A.J.Brook & D.B.Williamson, nom. illeg., A monograph on some British desmids… (2010: 267), non Closterium lunula var. giganteum (C.Bernard) Playfair (1908: 605) .

Synonyms: Closterium turgidum subsp. giganteum Nordstedt (in Wittrock & Nordstedt 1880: 120), Closterium turgidum var. giganteum (Nordstedt) De Toni (1889: 828) .

Note: The epithet is named for Carl Fredrik Otto Nordstedt (1838–1924), who originally described this material under the name Closterium turgidum subsp. giganteum Nordstedt (in Wittrock & Nordstedt 1880: 120, no fig.) based on material collected in a stream near Pirassununga, São Paulo State, Brazil.

Coesel & Meesters (2013: 117) transferred Staurastrum pseudosebaldi Wille to Staurastrum manfeldtii var. pseudosebaldi (Wille) Coesel & Meesters , implying a revaluation of taxonomic position of other varieties of Staurastrum pseudosebaldi . In Brazil, there are three varieties of Staurastrum pseudosebaldi reported in the literature: Staurastrum pseudosebaldi var. planctonicum Teiling ( Förster 1969, 1974), Staurastrum pseudosebaldi var. compactum A.M.Scott & Grönblad ( Ramos & al. 2018), and Staurastrum pseudosebaldi var. unguiculatum Borge ( Borge 1925, Grönblad 1945, Oliveira & al. 2017).

We consider that Staurastrum pseudosebaldi var. planctonicum Teiling as depicted by Förster (1969, 1974) is a misapplied name, and should be considered representative of Staurastrum johnsonii West & G.S.West. Coesel & Meesters (2013) studied representatives of the latter species from Europe and found specimens with 2(–3)-radiate semicells in apical view, with either an elliptic to fusiform or a triangular semicell. The Brazilian specimens correspond to the 3-radiate form of Staurastrum johnsonii .

On the other hand, the varieties compactum and unguiculatum are quite different from Staurastrum manfeldtii , particularly in apical view. The var. compactum has a triangular apical view with almost straight sides furnished with numerous bifid verrucae, and similar verrucae forming semicircles within the margins. Additionally, this variety has shorter processes (cell breadth with processes 45– 54 µm) than Staurastrum manfeldtii (cell breadth with processes 60–100 µm), and the isthmus is much wider with no basal inflation. Therefore, we consider these features sufficiently different to separate this variety from S. manfeldtii and consequently raise it to the species level, as follows: