taxonID	type	description	language	source
03868797B67E3469FDF5AF55FECEFC7F.taxon	description	The second group comprises the Xanthidium taxa that have Cosmarium - like morphology. We do not consider them members of genus Xanthidium because the spines are not confined to the cell angles, instead developing two superimposed series on each side of the semicell rather than continually along the margins. The Brazilian taxa of Xanthidium under discussion were proposed by Kurt Förster based on material gathered in the central (Förster 1964) and northern regions (Förster 1963). There are other species of Cosmarium like Xanthidium representatives such as C. horridum Borge (1899: 23), and C. paraguayense Borge (1903: 88), both of which are endemic to South America. However, Xanthidium obsoletum var. brasiliense Grönblad (1945: 22, fig. 158), another taxon based on material gathered in northern Brazil, is clearly related to Cosmarium. Nevertheless, we do not consider the information from the original description sufficient to propose a new combination for this taxon, as it resembles underdeveloped forms of other species such as Cosmarium paraguayense O. Borge (Borge 1903: 88, pl. 2: fig. 16) or C. guatemalense W. R. Taylor (Taylor 1939: 117, fig. 1: 1 – 3). Further studies, preferably at a populational level, are recommended to investigate this taxon as Grönblad included only dimensions from a unique cell that was illustrated only in front view. Additionally, there is a species originally proposed by Croasdale & Grönblad in Scott & al. (1965) from the Amazon basin, which was renamed subsequently by Croasdale (1971) as Xanthidium echinatum.	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67F3469FDF5AD34FECDFA7B.taxon	description	Synonym: Xanthidium echinatum Croasdale (in Grönblad & Croasdale), Acta Botanica Fennica 93: 40. 1971. Note: Grönblad in Scott & al. (1965) was at first uncertain about the identification of X. multispinosum and suggested the possibility of it being a Cosmarium or an Euastrum. The rectangular semicells with margins bearing very small spines, largest in the upper lateral corners, as well as the 4 irregular vertical rows of 3 or 4 spines across the face are morphological features most related to Cosmarium than Xanthidium. Xanthidium multispinosum Grönblad & Croasdale while illegitimate when treated as a Xanthidium is a valid name and becomes available within Cosmarium (Art. 58.1).	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67F3469FDF5AFAEFE2EF830.taxon	description	Note: This taxon requires a new name as the epithet “ luetzelburgii ” is already occupied by Cosmarium luetzelburgii Kurt Förster & Eckert in Förster (1964: 395, pl. 23: fig. 2; pl. 42: fig. 17). The new epithet is coined for Roraima State, northern Brazil, from where the species was originally described.	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67F346AFDF5AEF7FCC4FE2B.taxon	description	Note: This species requires a new name as the epithet “ multituberculatum ” was already used by Cosmarium multituberculatum F. E. Fritsch & M. F. Rich (Fritsch & Rich 1937: 189, fig. 18 A – O). The new epithet refers to the Cerrado biome, the largest savanna-like region in South America, from where the species was originally described.	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67C346AFDF5AC17FAF0F8A5.taxon	description	Note: While Förster’s original description lacks an explicit designation of type, a single gathering was indicated “ Rio das Femmeas bei Porta Azul (Goyaz) ”, currently Tocantins State (ca. 13 ° S, ca. 48 ° W), which serves to validate the name (Art. 40.2). The new epithet derives from the spiny cell wall. It should also be noted that “ Cosmarium aculeatum Corda ” (Corda 1839: 218), is an invalid name as it cited “ Euastr. Ehr. 1. c. fig. II. ”, a clear reference to Ehrenberg (Atlas 1838: legend to pl. XII [12], fig. II [2]) a lapsus calami for Euastrum apiculatum Ehrenberg, 1838 (see text p. 112) and is thus an invalid name. Additionally, “ Cosmarium aculeatum Brébisson ” [in Meneghini 1840: 218, based on “ Binatella aculeata Brébisson ” (Brébisson & Godey 1835: 58, pl. VII pro parte; also invalid] is invalid as a pre-starting point name for the group even though it was provided with a description and an illustration. Both of the latter designations were validated as Micrasterias apiculata Meneghini ex Ralfs (1848: 209).	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67C346BFDF5AE42FA6EFEE5.taxon	description	Note: While Förster’s original description lacks an explicit designation of type, a single gathering was indicated “ Rio das Femmeas bei Porta Azul (Goyaz) ”, currently Tocantins State (ca. 13 ° S, ca. 48 ° W), which serves to validate the name (Art. 40.2). The new epithet refers to the Cerrado biome, the largest savanna-like region in South America, from which the species was collected.	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67D346BFDF5A882FA88F9C0.taxon	description	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:	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67D346BFDF5AF67FC7FF817.taxon	description	Note: Staurastrum mississippiense is a rare species known only from a pond on old road, 6 miles east of Pearlington, Mississippi (Scott & Grönblad 1957: 8, 44) and from Bahia, north-eastern Brazil (Ramos et al. 2018). As the epithet “ compactum ” is already occupied at the species level by Staurastrum compactum Whelden (Whelden 1947: 99, pl. VI: fig. 7), we chose “ mississippiense ” to replace it based on the type locality.	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67A346CFDF5A9CAFAD4FCC4.taxon	description	Förster (1969: 44) applied the name Actinotaenium peniomorphum var. latius (A. M. Scott & Prescott) Kurt Förster to material collected in the Amazon basin, Brazil. However, Actinotaenium peniomorphum is an illegitimate name as it is based upon Cosmarium peniomorphum A. M. Scott & Prescott, an illegitimate replacement name for Penium variolatum West & G. S. West (West & West 1897: 77, pl. 368: fig. 23). Thus, Actinotaenium peniomorphum var. latius is also an illegitimate varietal name as it is included in an illegitimate species. Taxonomically, A. peniomorphum var. latius sensu Kurt Förster should is referable Actinotaenium crassiusculum (De Bary) Teiling.	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
03868797B67A346EFDF5AA7CFACDFC36.taxon	description	We are grateful to Michael D. Guiry and anonymous reviewer for their valuable suggestions and corrections leading to an improvement of the manuscript. Borge, O. (1899). Ueber tropische und subtropische Süsswasser-Chlorophyceen. Bihang til Kongliga Svenska Vetenskaps-Akademiens Handlingar 24 (Afd. III, 12): 1 – 33. Borge, O. (1903). Die Algen der ersten Regnellschel Expedition. 2. Dedsmidiaceen. Arkiv für Botanik 1: 71 – 138. Borge, O. (1925) Die von Dr. F. C. Hoehne während der Expedition Roosevelt-Rondon gesammelten Süsswassernalgen. Arkiv for Botanik 19: 1 – 56. Brébisson, L. A. de & Godey, L. L. (1835 ‘ 1836 ’). Algues des environs de Falaise, décrites et dessinées par MM. De Brébisson et Godey. Mémoires de la Société Académique des Sciences, Artes et Belles-Lettres de Falaise 1835: 1 – 62, 256 – 269 [corrections]. Brook, A. J. & Williamson, D. B. (2010). A monograph on some British desmids. Order Zygnematales Suborder Zygonemoidiineae Family Zygnemataceae Subfamily Mesotaenioideae (Saccoderm desmids) and Suborder Closteriineae Family Peniaceae and Family Closteriaceae. Edited by J. H. Price & N. J. Evans. pp. [i – ii], iii – v [1 – 5], 6 – 364. London: The Ray Society. Coesel, P. F. M. & Meesters, K. J. (2013). European flora of the desmid genera Staurastrum and Staurodesmus. [1] – 357. Zeist: KNNW Publishing. Corda, A. J. C. (1839). Observations sur les Euastrées et les Cosmariées. Almanach de Carlsbad 9: 213 – 244. De Bary, A. (1858). Untersuchungen über die Familie der Conjugaten (Zygnemeen und Desmidieen) Ein Beitrag zur physiologischen und beschreibenden Botanik. pp. [i] – vi, 1 – 91. A. Förstnersche Buchhandlung (Arthur Felix), Leipzig. De Toni, G. B. (1889). Sylloge algarum omnium hucusque cognitarum. Vol. I. Chlorophyceae. pp. [3] – 12, [i] – cxxxix, 1 – 1315. Patavii [Padua]: Sumptibus auctoris. Ehrenberg, C. G. (1834). 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Transactions of the Linnean Society of London, Botany, Series 2, 6: 123 – 215. Whelden, R. M. (1947). Algae. National Museum of Canada Bulletin 97: 13 – 127. Wittrock, V. B. & Nordstedt, C. F. O. (1880). Algae aquae dulcis exsiccatae praecipue Scandinavicae quas adjectis algis marinis chlorophyllaceis et phycochromaceis. Lundae: O. L. Svanbäcks Boktryckeri Aktiebolac, fasc. 8, exsic. 351 – 400. Wolle, F. (1883). Fresh-water algae, 7. Bulletin of the Torrey Botanical Club 10 (2): 13 – 21.	en	Ramos, Geraldo José Peixoto (2022): Nomenclatural and taxonomic notes on Brazilian desmids IV. Notulae Algarum 224: 1-7, DOI: 10.5281/zenodo.16652630
