taxonID	type	description	language	source
03CB3545FFBCFF80FF18860EFBB11E6A.taxon	description	Description: Cell as long as wide; semicell subquadrangular, 4 - lobed, apical margin with deep median incision, rounded apical angles, one long, pointed spine; lateral margins concave, subquadrangular, basal angles with short, divergent, bifurcate spines; each semicell with a large truncate central papilla; median constriction deep, median sinus open, acute-angled; cell wall smooth; chloroplast axial. Cells 25 - 30 μm long (with spines), 19 - 21 μm (without spines), 20 - 26 μm wide (with spines), 16.5 - 21 μm (without spines), 4 - 4.5 μm isthmus width, 13 - 14 μm wide at apex (without spines). Holotype: Förster (1964: pl. 6: fig. 5 [top specimen, two views of the same specimen], as “ Euastrum arciferum var. longispinum Förster ”; ICN Art. 40.5, Turland & al. 2018), here reproduced as Fig. 1. Type locality: Rio da Femmeas, state of Tocantins, Brazil. PhycoBank Registration: 103604 Etymology: Named in honour of the eminent desmidologist Kurt Förster (1918 – 1983), who originally described the material. Occurrence in Brazil: Rio da Femmeas, Tocantins state (Förster 1964, Goiás state; as “ Euastrum arciferum var. longispinum Kurt Förster ”, nom. inval.); Arapiuns river – Lake Curi and Lake Mentaí (Scott & al. 1965, as “ Euastrum foersteri Scott & Croasdale ”, nom. inval.), Lake Jurucuí (Förster 1969, “ Euastrum foersteri Scott & Croasdale ”, nom. inval.), Pará state; Nhamundá Region, Amazonas state (Thomasson 1977, just citation). The name “ Pleurotaenium tridentulum var. tenuissimum ” introduced by Grönblad & Croasdale (in Scott & al. 1965: 30, pl. 2: figs 33 - 34) and a new combination “ Pleurotaenium tenuissimum Förster ” (Förster 1981: 246) were not validly published since they were also not based on a single gathering (ICN Art. 40.2, Shenzhen Code, Turland & al. 2018), and a type locality was not designated from the two localities listed in Scott & al. (1965): “ Rio Arapiuns ”, above the “ Ponta Icuxi ” (Nr. 20, a tributary of the Tapajós River, Pará state, Brazil) and the mouth of “ Rio Uaupés ” (Nr. 21, a tributary of the Rio Negro basin, state of Amazonas, Brazil). Although Grönblad & Croasdale (1971: 40) designated fig. 34 of Scott & al. (1965) as the holotype, the designation “ Pleurotaenium tridentulum var. tenuissimum ” remains invalid as a full and direct reference the place of valid publication, with page or plate reference and date were not given (ICN Art. 41.5, Shenzhen Code, Turland & al. 2018). Furthermore, the shape of “ Pleurotaenium tridentulum var. tenuissimum ” deviates considerably from the shape of P. tridentulum species (Förster 1981). Furthemore, Pleurotaenium tridentulum (Wolle) West is now considered a heterotypic later synonym of Pleurotaenium sceptrum (Roy) West & G. S. West (e. g. Prescott & al. 1975; Araújo & al. 2022). Thus, we here validate “ Pleurotaenium tenuissimum ” by providing it with a formal description and a type based on the material studied by Grönblad & Croasdale (in Scott & al. 1965) and Kurt Förster (in Förster 1969, 1974, 1981). Also, we link here all taxa and their published illustrations that represents this species and its distribution in Brazil.	en	Araújo, Camila Barbosa de (2023): Taxonomic and nomenclatural notes on two desmid species from Brazil (Desmidiaceae, Zygnematophyceae). Notulae Algarum 269: 1-4, DOI: 10.5281/zenodo.16652662
03CB3545FFBDFF82FF188730FDF91835.taxon	description	Description: Cells longer than wide; semicell cylindrical, apex subquadrangular with 4 more or less conical rounded warts squarely arranged; lateral margins parallel, abruptly attenuated to the apex; median constriction shallow; median sinus poorly developed; no central swelling; cell wall hyaline; chloroplast axial; 4 - 8 pyrenoids by semicell. Cells 238 - 255 μm long, 6.5 - 8 μm wide, 2.5 - 3 μm wide at apex. Holotype: Scott & al. (1965: pl. 30: fig. 34, as “ Pleurotaenium tridentulum var. tenuissimum ”; ICN Art. 40.5, Turland & al. 2018), here reproduced as Fig. 4 (fig. 33, left). Type locality: Arapiuns River, a tributary of the Tapajós River, State of Pará, Brazil. PhycoBank Registration: 103602 Etymology: From Latin tenuis, - e (adj.), thin, fine, slender (narrow); superlative tenuissimus, - a, - um, (very slender). Occurrence in Brazil: This species is reported from the Amazon region as Pleurotaenium tridentulum var. tenuissimum Grönblad & Croasdale ”, nom. inval.; Amazonas state (Scott & al. 1965; Förster 1969, 1974; Uherkovich & Rai 1979, just citation); Pará state (Scott & al. 1965), as “ Pleurotaenium tenuissimum Kurt Förster ”, nom. inval. (Förster 1981). We are grateful to Professor Michael Guiry and several reviewers for their valuable recommendations leading to an improvement of the manuscript. Araújo, C. B., Furtado, M. F. M., Melo, S., Takiyama, L. R., Cantuária, P. C., Bicudo, C. E. M. (2022). Some interesting desmids (Desmidiaceae, Zygnematophyceae): first records, taxonomic notes, and distribution for the Amazon Brazilian flora. Check List 18 (6): 1337 – 1346, 13 figs. Borge, O. (1918). Die von Dr. A. Löfgren in São Paulo gesammelten Süsswasseralgen. Arkiv för Botanik 15 (13): 1 – 108. Förster, K. (1964). Desmidiaceen aus Brasilien, 2: Bahia, Goyaz, Piauhy und Nord-Brasilien. Hydrobiologia 23: 321 – 505. Förster, K. (1969). Amazonische Desmidieen, 1: Areal Santarém. Amazoniana 2 (1 / 2): 5 – 116. Förster, K. (1974). Amazonische Desmidieen, 2: Areal Maués - Abacaxis. Amazoniana 5: 135 – 242. Förster, K. (1981). Revision und Validierung von Desmidiaceen-Namen aus früheren Publikationen, 2. Algological Studies 28: 236 – 251. Grönblad, R. & Croasdale, H. (1971). Desmids from Namibia (SW Africa). Acta Botanica Fennica 93: 1 – 40. Prescott, G. W., Croasdale, H. T. & Vinyard, W. C. (1975). A synopsis of North American desmids. Part II. Desmidiaceae: Placodermae. Sect. 1. pp. 1 - 275, 57 pls. Lincoln: University of Nebraska Press. Scott, A. M., Grönblad, R. & Croasdale, H. (1965). Desmids from the Amazon Basin, Brasil. Acta Botanica Fennica 69: 3 – 93. Thomasson, K. (1977). Two conspicuous desmids from Amazonas. Botaniska Notiser 130: 41 – 51. Turland, N. J., Wiersema, J. H., Barrie, F. R., Greuter, W., Hawksworth, D. L., Herendeen, P. S., Knapp, S., Kusber, W. - H., Li, D. - Z., Marhold, K., May, T. W., McNeill, J., Monro, A. M., Prado, J., Price, M. J. & Smith, G. F., editors (2018). International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code) adopted by the Nineteenth International Botanical Congress Shenzhen, China, July 2017. Regnum Vegetabile, Vol. 159. pp. [i] - xxxviii, 1 – 253. Glashütten: Uherkovich, G. & Rai, H. (1979) Algen aus den Rio Negro und seinen Nebenflüssen. Amazoniana 6 (4): 611 – 638. as originally illustrated by Scott & Croasdale (in Scott & al. 1965: p. 32, pl. 4, figs 69 - 70 as “ Euastrum foersteri ”). Fig. 3. Euastrum foersteri sp. nov.: as originally illustrated by Förster (1969: 33, pl. 9: figs 22, 23. Scale bar: fig. 22: 30 µm; fig. 23: 50 µm, as “ Euastrum foersteri ”). Fig. 4. Pleurotaenium tenuissimum sp. nov.: holotype (left “ 33 ”), the original illustration of “ Pleurotaenium tridentulum var. tenuissimum ” published by Grönblad & Croasdale (in Scott & al. 1965: 30, pl. 2: figs 33, 34). Fig. 5. Pleurotaenium tenuissimum sp. nov.: holotype originally illustrated by Förster (1969: 28, pl. 6: figs 8 - 10. Scale bar: figs 8 - 9: 50 µm; fig. 10: 30 µm) as “ Pleurotaenium tridentulum var. tenuissimum ”. Fig. 6. Pleurotaenium tenuissimum sp. nov.: material originally illustrated by Förster (1974: 153, pl. 4: figs 8, 9) as “ Pleurotaenium tridentulum var. tenuissimum ”.	en	Araújo, Camila Barbosa de (2023): Taxonomic and nomenclatural notes on two desmid species from Brazil (Desmidiaceae, Zygnematophyceae). Notulae Algarum 269: 1-4, DOI: 10.5281/zenodo.16652662
