Abstract:

Eunotia species from a stream located in the surrounding area of the Iguaçu National Park conservation unit were analyzed. Samples were monthly collected from September 2012 to August 2013. The periphytic material, manually obtained by squeezing aquatic macrophytes, was oxidized and analyzed under light and scanning electron microscopy. Twenty-one infrageneric taxa of Eunotia were identified, measured, and illustrated. Eunotia caniculoides sp. nov. is proposed as a new species, and eight taxa are new records for Paraná state.

Keywords:
Bacillariophyta; diatoms; periphyton; southern Brazil; taxonomy

Resumo:

Espécies de Eunotia Ehrenberg de um ambiente lótico localizado em área adjacente à unidade de conservação Parque Nacional do Iguaçu foram analisadas. As coletas foram realizadas mensalmente de setembro de 2012 a agosto de 2013. O material perifítico obtido do espremido manual de macrófitas aquáticas foi oxidado e analisado sob microscopia óptica e eletrônica de varredura. Vinte e um táxons de Eunotia foram identificados, medidos e ilustrados. Eunotia caniculoides sp. nov. é proposta como uma nova espécie e oito táxons constituem novos registros para o estado do Paraná.

Palavras-chave:
Bacillariophyta; diatomáceas; perifíton; sul do Brasil; taxonomia

Introduction

The genus Eunotia Ehrenberg is characterized by the valve isopolarity, apical axis asymmetry, uniseriate striae, short raphe system, usually restricted to the valve apices and the presence of rimoportulae (Kociolek & Spaulding 2003KOCIOLEK, J.P. & SPAULDING, S. 2003. Eunotioid and asymmetrical naviculoid diatoms. In Freshwater Algae of North America. Ecology and classification. (J.D. Wehr & R.G.F. Sheath, eds). London, Academic Press Elsevier Science., Furey 2011FUREY, P.C, LOWE, R.L. & JOHANSEN, R.J. 2011. Eunotia Ehrenberg (Bacillariophyta) of the Great Smoky Mountains National Park, USA. Biblioth. Diatomol. 56:1-133.). The extant species are found in freshwater environments (Round et al. 1990ROUND, F.E., CRAWFORD, R.M. & MANN, D.G. 1990. The Diatom: biology and morphology of the genera. Cambridge University Press.) but some fossil Eunotia have already been described from marine sediments in New Zealand (Novitski & Kociolek 2005NOVITSKI, L. & KOCIOLEK, P. 2005. Preliminary light and scanning electron microscope observations of marine fossil Eunotia species with remarks on the evolution of the genus. Diatom Res. 20(1): 137-143. https://doi.org/10.1080/0269249X.2005.9705623.
https://doi.org/10.1080/0269249X.2005.97... ). The genus includes species with ecological optimum in the epiphyton and metaphyton of dystrophic to oligotrophic waters, being valuable indicators of acidic and low-conductivity conditions (Round et al. 1990ROUND, F.E., CRAWFORD, R.M. & MANN, D.G. 1990. The Diatom: biology and morphology of the genera. Cambridge University Press., Van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Netherlands J. Aquat. Ecol. 28: 117-133., Cantonati & Lange-Bertalot, 2011CANTONATI, M. & LANGE-BERTALOT, H. 2011. Diatom monitors of close-to-pristine, very-low alkalinity habitats: three new Eunotia species from springs in Nature Parks of the south-eastern Alps. J. Limnol. 70: 209-221. https://doi.org/10.4081/jlimnol.2011.209.
https://doi.org/10.4081/jlimnol.2011.209... , Cox 2015COX, E. 2015. Coscinodiscophyceae, Mediophyceae, Fragilariophyceae, Bacillariophyceae (Diatoms). In: Frey, W. (Ed.). Syllabus of plant families. A. Engler Syllabus der Pflantzenfamilien. 2/1 Photoautotrophic eukaryotic algae. Borntraeger, Stuttgart, p. 64-103.).

Eunotia is one of the most common and species-rich diatom genera in the Neotropics (Patrick 1940aPATRICK, R. 1940a. Some new diatoms from Brazil. Not. Nat. 59: 1-7., 1940bPATRICK, R. 1940b. some nomenclatural problems and a new species and a new variety in the genus Eunotia (Bacillariophyceae). Not. Nat. 312: 1-15., Hustedt 1952aHUSTEDT, F. 1952a. Neue und wenig bekannte Diatomeen. III. Phylogenetische Variationen bei den raphidioiden Diatomeen. Ber. Deutsch. Bot. Ges. 65: 133-145., 1952bHUSTEDT, F. 1952b. Neue und wenig bekannte Diatomeen. IV. Botaniska Notiser, Hafte 4: 366-410., 1965HUSTEDT, F. 1965. Neue und wenig bekannte Diatomeen. IX. Süßwasser diatomeen aus Brasilien, insbesondere des Amazonas gebietes. Int. Rev. Hydrobiol. 50: 391-410., Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical Diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 5: 1-220., 2007METZELTIN, D. & LANGE-BERTALOT, H. 2007. Tropical Diatoms of south America II. Special remarks on biogeographic disjunction. In Iconographia Diatomologica, Annotated Diatom Monographs.(H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 18: 1-1876., Sala et al. 2002aSALA, S.E., DUQUE, S.R., NUÑEZ-AVELLANEDA, M. & LAMARO, A.A. 2002a. Diatoms from the Colombian Amazon: some species of the genus Eunotia (Bacillariophyceae). Acta Amazon. 32: 589-603. https://doi.org/10.1590/1809-43922002324603.
https://doi.org/10.1590/1809-43922002324... , 2002bSALA, S.E., DUQUE S.R., NUÑEZ-AVELLANEDA, M. & LAMARO, A.A. 2002b. Diatoms from the Colombian Amazonia. Cryptogam. Algol. 23: 75-99., Dunck et al 2016DUNCK, B., RUWER, D.T. & FELISBERTO, S.F. (2016) Eunotiaceae Kützing (Bacillariophyceae) perifíticas de áreas úmidas do Cerrado (veredas) no Brasil. Iheringia, sér. Bot. 71(3): 283-295., Faustino et al. 2016FAUSTINO, S.B., FONTANA, L., BARTOZEK, E.C.R., BICUDO, C.E.M., BICUDO, D.C. 2016. Composition and distribution of diatom assemblages from core and surface sediments of a water supply reservoir in Southeastern Brazil. Biota Neotropica 16(2): e20150129. https://doi.org/10.1590/1676-0611-BN-2015-0129.
https://doi.org/10.1590/1676-0611-BN-201... , Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Bibl. Diatomol. 64: 1-302.), with remarkable diversity in Brazilian acidic environments (Ferrari et al. 2007FERRARI, F., PROCOPIAK, L.K., ALENCAR, Y.B. & LUDWIG, T.A.V. 2007. Eunotiaceae (Bacillariophyceae) em igarapés da Amazônia Central, Manaus e Presidente Figueiredo, Brasil. Acta Amaz. 37:1-16. http://dx.doi.org/10.1590/S0044-59672007000100001.
http://dx.doi.org/10.1590/S0044-59672007... , Bicca et al. 2011BICCA, A.B., TORGAN, L.C. & SANTOS, C.B. 2011. Eunotiaceae (Eunotiales, Bacillariophyta) em ambientes lacustres na Planície Costeira do Sul do Brasil. Rev. Bras. Bot. 34: 1-19. https://doi.org/10.1590/S0100-84042011000100002.
https://doi.org/10.1590/S0100-8404201100... , Canani & Torgan 2013CANANI, L.G. & TORGAN, L.C. 2013. Two new Eunotia species with subapical costae, an uncommon structure for the genus. Diatom Res. 28(4): 395-406. https://doi.org/10.1080/0269249X.2013.821425.
https://doi.org/10.1080/0269249X.2013.82... , Dunck et al. 2013aDUNCK, B., NOGUEIRA, I.S. & FELISBERTO, S.A. 2013a. Distribution of periphytic Algae in wetlands (Palm swamps, Cerrado), Brazil. Braz. J. Biol. 73: 331-346. https://doi.org/10.1590/S1519-69842013000200013
https://doi.org/10.1590/S1519-6984201300... , 2013bDUNCK, B., NOGUEIRA, I.S. & FELISBERTO, S.A. 2013b. Composição e diversidade de algas perifíticas em veredas sob diferentes impactos antrópicos (Goiás, Brasil). Iheringia. Sér. Bot. 68: 237-248., 2016DUNCK, B., RUWER, D.T. & FELISBERTO, S.F. (2016) Eunotiaceae Kützing (Bacillariophyceae) perifíticas de áreas úmidas do Cerrado (veredas) no Brasil. Iheringia, sér. Bot. 71(3): 283-295., Cavalcante et al. 2014CAVALCANTE, K.P., TREMARIN, P.I., CASTRO, E.C., TIBIRIÇÁ, C.E.J.A., WOJCIECHOWSKI, J. & LUDWIG, T.A.V. 2014. Epiphytic Eunotia (Bacillariophyceae) on Podostemum from Santa Catarina, southern Brazil, including new observations on morphology and taxonomy of some rare recorded species. Biota Neotrop. 14(3): 1-12. https://doi.org/10.1590/1676-06032014003414.
https://doi.org/10.1590/1676-06032014003... ). In the state of Paraná, the genus were reported by Ludwig & Valente-Moreira (1989)LUDWIG, T.A.L. & VALENTE-MOREIRA, I.M. 1989. Contribuição ao conhecimento da diatomoflórula do parque regional do Iguaçu, Curitiba, Paraná, Brasil: I. Eunotiaceae (Bacillariophyceae). Arq. Biol. Tecnol. 32: 543-560., Fürstenberger & Valente-Moreira (2000)FÜRSTENBERGER, C. & VALENTE-MOREIRA, I.M. 2000. Diatomáceas (Bacillariophyta) perifíticas da lagoa Tarumã, Ponta Grossa, Paraná, Brasil. Insula 29: 117-134., Tremarin et al. (2008)TREMARIN, P.I., LUDWIG, T.A.V. & MOREIRA-FILHO, H. 2008. Eunotia Ehrenberg (Bacillariophyceae) do rio Guaraguaçu, litoral do Paraná, Brasil. Acta Bot. Bras. 22: 845-867. https://doi.org/10.1590/S0102-33062008000300020
https://doi.org/10.1590/S0102-3306200800... , Faria et al. (2010)FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales e Gomphonema Ehrenberg. Biota Neotrop. (10)3: 415-527. http://dx.doi.org/10.1590/S1676-06032010000300035.
http://dx.doi.org/10.1590/S1676-06032010... , Bertolli et al. (2010)BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24: 1065-1081. https://doi.org/10.1590/S0102-33062010000400022
https://doi.org/10.1590/S0102-3306201000... , Santos et al. (2011)SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotrop. 11(3): 303-315. http://dx.doi.org/10.1590/S1676-06032011000300025
http://dx.doi.org/10.1590/S1676-06032011... , Bartozek et al. (2013)BARTOZEK, E.C.R., BUENO, N.C., LUDWIG, T.A.V., TREMARIN, P.I., NARDELLI, M.S. & ROCHA, A.C.R. 2013. Diatoms (Bacillariophyceae) of Iguaçu National Park, Foz do Iguaçu, Brazil. Acta Bot. Bras. 27(1): 108-123. http://dx.doi.org/10.1590/S0102-33062013000100012.
http://dx.doi.org/10.1590/S0102-33062013... , Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... , Silva-Lehmkuhl et al. (2019)SILVA-LEHMKUHL, A.M., TREMARIN, P.I., VERCELINO, I.S. & LUDWIG, T.A.V. 2019. Periphytic diatoms from na oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil. Biota Neotrop. 19(2): e20180568. https://doi.org/10.1590/1676-0611-bn-2018-0568.
https://doi.org/10.1590/1676-0611-bn-201... , and Bartozek et al. (2020)BARTOZEK, E.C.R., TREMARIN, P.I., PERES, C.K. & BRANCO, C.C.Z. 2020. Eunotia itacueretabaensis sp. nov. (Bacillariophyceae, Eunotiaceae) from the Campos Gerais region, Southern Brazil. Phytotaxa 439(1): 067-076. https://doi.org/10.11646/phytotaxa.439.1.4.
https://doi.org/10.11646/phytotaxa.439.1... recently proposed a new species. Based on a bibliographic check-list of freshwater diatom studies developed in the state of Paraná from 1954 to 2009, Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107. listed 110 Eunotia infrageneric taxa, and Cavalcante et al. (2014)CAVALCANTE, K.P., TREMARIN, P.I., CASTRO, E.C., TIBIRIÇÁ, C.E.J.A., WOJCIECHOWSKI, J. & LUDWIG, T.A.V. 2014. Epiphytic Eunotia (Bacillariophyceae) on Podostemum from Santa Catarina, southern Brazil, including new observations on morphology and taxonomy of some rare recorded species. Biota Neotrop. 14(3): 1-12. https://doi.org/10.1590/1676-06032014003414.
https://doi.org/10.1590/1676-06032014003... mention about 245 taxa registered to Brazil.

The purpose of the present publication was to investigate the species diversity of Eunotia from a stream located in the surrounding area of the Iguaçu National Park conservation unit. A new species, Eunotia caniculoides, was formally described. The distinctive characters between similar taxa were discussed and taxonomical notes were provided. Distribution in the state of Paraná and ecological informations were also added.

Material and Methods

The present study was carried out on the Tenente João Gualberto stream, located in a conservation unit area adjacent to the Iguaçu National Park, in the municipality of São Miguel of Iguaçu (25º28’36.3”S; 54º19’40.9”W), the western region of the state of Paraná. According to Horton-Strahler criteria (Horton 1945HORTON, R.E. 1945. Erosional development of streams and their drainage basins: hydrophysical approach to quantitative morphology. Geol. Soc. Am. Bull. 56: 275-370., Strahler 1952STRAHLER, A.N. 1952. Hypsometric (area-altitude) analysis of erosional topology. Geol. Soc. Am. Bull. 63: 1117-1142.), the stream is a major tributary of the Baixo Iguaçu Basin, having its source and part of its course among agricultural fields (Figure 1). The regional climate is Cfa type, subtropical humid mesotherm, with well-defined summer and winter periods, and rains distributed during the year (Alvares et al. 2013ALVARES, C.A., STAPE, J.L., SENTELHAS, P.C., GONÇALVES, J.L.M. & SPAROVEK, G. 2013. Köppen’s climate classification map for Brazil. Meteor. Zeitsch. 22: 711-728.).

Diatom samples were collected monthly, from September 2012 to August 2013. Limnological variables as dissolved oxygen (mg L^-1), pH, water temperature (ºC), conductivity (mS cm^-1), and turbidity (NTU) were measured in the field using a Horiba U-5000 multiparameter probe. Nutrient analysis of organic nitrogen - N_org. (mg L^-1), ammoniac nitrogen - NH₄⁺ (mg L^-1), nitrate - NO₃^- (mg L^-1), nitrite - NO₂^- (mg L^-1), orthophosphate - PO₄^-3 (mg L^-1) e total phosphorous - TP (mg L^-1, were carried out at the Limnological Laboratory of the Research Group on Fishery Resources and Limnology (GERPEL), from UNIOESTE, campus Toledo, according to American Public Health Association (2005)AMERICAN PUBLIC HEALTH ASSOCIATION. 2005. Standard Methods for Examination of Water and Wastewater. APHA, Washington.. Weekly precipitation (mm) data were provided by Paraná Meteorological System (SIMEPAR). Minimum and maximum values of limnological data were described for each identified Eunotia species.

Periphytic samples were removed by manually squeezing the aquatic macrophyte Eleocharis minima Kunth (Cyperaceae) and were preserved in Transeau solution, in 1:1 proportion (Bicudo & Menezes 2017BICUDO, C.E.M. & MENEZES, M. 2017. Gêneros de algas de águas continentais do Brasil. RiMa, São Carlos.). The organic matter was eliminated by oxidation with KMnO₄ and HCl according to Simonsen (1974)SIMONSEN, R. 1974. The diatom plankton of Indian Ocean Expedition of RV “Meteor” Meteor 1964-1965. Meteor Forschungsergebnisse, Reihe D: Biologie 19: 1-107. technique modified by Moreira-Filho & Valente-Moreira (1981)MOREIRA-FILHO, H. & VALENTE-MOREIRA, I.M. 1981. Avaliação taxonômica e ecológica das diatomáceas (Bacillariophyceae) epífitas em algas pluricelulares obtidas nos litorais dos Estados do Paraná, Santa Catarina e São Paulo. Bol. Mus. Bot. Mun. 47: 1-17.. Cleaned material was dried onto glass coverslips and mounted on slides with Naphrax® (IR= 1.74). The taxonomic analysis was performed using an Olympus BX60 light microscope equipped with a DP71 image capture camera. Subsamples from cleaned samples were mounted on aluminum stubs and coated with gold. Micrographs were taken with JEOL JSM 6360 scanning electron microscope (SEM), operated at15 kV and 8mm working distance, housed in the Electron Microscopy Center from the Federal University of Paraná. Slides and samples were deposited in the UNOPA Herbarium, UNIOESTE, campus Cascavel and registered as shown in Table 1.

Morphological terminology follows Barber & Haworth (1981)BARBER, H.G. & HAWORTH, E.Y. 1981. A guide to the morphology of the diatom frustule. Fresh. Biol. Assoc. 44: 1-112. and Round et al. (1990)ROUND, F.E., CRAWFORD, R.M. & MANN, D.G. 1990. The Diatom: biology and morphology of the genera. Cambridge University Press.. The classification system was based on Cox (2015)COX, E. 2015. Coscinodiscophyceae, Mediophyceae, Fragilariophyceae, Bacillariophyceae (Diatoms). In: Frey, W. (Ed.). Syllabus of plant families. A. Engler Syllabus der Pflantzenfamilien. 2/1 Photoautotrophic eukaryotic algae. Borntraeger, Stuttgart, p. 64-103..

Every Eunotia species was measured at the valve apical length, transapical width and striae density in the central part of the valve. The ecological information cited for identified taxa corresponds to the abiotic parameters measured in the samples collected during this study.

Constancy is a measure of species occurrence (C) and was expressed as follows: constant (C ≥ 70%), common (30% ≥ C ≤ 70%), sporadic (10% ≥ C ≤ 30%) and rare (C ≤ 10%) (Dajoz 2005DAJOZ, R. 2005. Princípios de Ecologia. Artmed, Porto Alegre.).

Results

Twenty-one taxa were measured and illustrated. Eight Eunotia taxa are new records for the state of Paraná: E. georgii Metzeltin & Lange-Bertalot, E. karenae Metzeltin & Lange-Bertalot, E. guianensis (Ehrenberg) De Toni, E. juettnerae Lange-Bertalot, E. pileus Ehrenberg, E. pseudosudetica var. rotundata Cavalcante, Tremarin & T.Ludwig, E. sedina Lange-Bertalot, Bak & Witkowski, and E. tropico-arcus Metzeltin & Lange-Bertalot. Eunotia caniculoides sp. nov. is formally proposed as a new species and are compared with close taxa (Table 2). The occurrence of species in the samples as well as ecological and environmental data from the sampling are listed in Table 3.

Bacillariophyceae Haeckel

Eunotiophycidae D.G. Mann

Eunotiales P.C. Silva

Eunotiaceae Kützing

Eunotia Ehrenberg

Eunotia ambivalens Lange-Bertalot & Tagliaventi. In: Lange-Bertalot (ed.), Diatoms of Europe 6, p. 49, pl. 11, figs 1‒11, pl. 12, figs 1‒6, pl. 13, figs. 1‒11, 2011.

Figures 2a‒2d, 4a.

Valves slightly arched, 77.6‒177.3 µm long and 4.2‒5.6 µm wide. Dorsal margin convex, ventral margin concave. Apices rounded. Terminal nodules near the apices. Striae parallel, 11‒12 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM. In SEM: presence of short marginal spines, ca. 41 areolae in 10 µm.

Frequency of occurrence: common (Table 3).

Paraná State citations: cited as E. bilunaris var. linearis (Okuno) Lange-Bertalot & Nörpel-Schempp: Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Faria et al. (2010)FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales e Gomphonema Ehrenberg. Biota Neotrop. (10)3: 415-527. http://dx.doi.org/10.1590/S1676-06032010000300035.
http://dx.doi.org/10.1590/S1676-06032010... , Santos et al. (2011)SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotrop. 11(3): 303-315. http://dx.doi.org/10.1590/S1676-06032011000300025
http://dx.doi.org/10.1590/S1676-06032011...

Taxonomic remarks:Eunotia ambivalens distinguishes from E. bilunaris by slightly arched valves, almost parallel margins, ends not protracted, lower striae density (11.5‒13/10 µm vs 13‒17/10 µm), and by the presence of marginal spines (Figure 3a) only discernible in SEM (Lange-Bertalot et al. 2011LANGE-BERTALOT, H., BAK, M., WITKOWSKI, A. & TAGLIAVENTI, N. 2011. Eunotia and some related genera. In Diatoms of Europe (H. Lange-Bertalot ed). Gantner Verlag K.G., Ruggell, 747 p.). The species “locus typicus” is Albania, Flower Lake, Lura Mountais, but it was also observed in oligotrophic alkaline or slightly acidic waters with low to moderate conductivity (Lange-Bertalot 2011LANGE-BERTALOT, H., BAK, M., WITKOWSKI, A. & TAGLIAVENTI, N. 2011. Eunotia and some related genera. In Diatoms of Europe (H. Lange-Bertalot ed). Gantner Verlag K.G., Ruggell, 747 p.).

Eunotia bilunaris (Ehrenberg) Schaarschmidt. In: Kanitz, Magyar Novenytani Lapok 5: 159, 1880.

Basionym: Synedra bilunaris Ehrenberg. Abh. Königl. Akad. Wiss. Berl. 1831: 87, 1832.

Figures 2e‒2j, 4b‒c.

Valves arched tapering toward apices, 16.2‒98.7 µm long and 3.1‒4.6 µm wide. Dorsal margin convex, ventral margin concave sometimes with median swelling (Figure 2e-2j). Apices rounded to acutely rounded. Terminal nodules near the apices. Distal raphe end strongly curved onto the valve face. One rimoportula per valve, near the apex. Striae parallel, denser near the apices, 12‒15 in 10 µm in the middle region of the valve. Areolae rounded, not visible in LM. Cingulum composed of four open bands perforated by a linear row of pores.

Frequency of occurrence: constant (Table 3).

Paraná State citations: Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Faria et al. (2010)FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales e Gomphonema Ehrenberg. Biota Neotrop. (10)3: 415-527. http://dx.doi.org/10.1590/S1676-06032010000300035.
http://dx.doi.org/10.1590/S1676-06032010... , Silva et al. (2010)SILVA, A.M., LUDWIG, T.A.V., TREMARIN, P.I. & VERCELINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Bot. Bras. 24(4): 997-1016. https://doi.org/10.1590/S0102-33062010000400015.
https://doi.org/10.1590/S0102-3306201000... , Santos et al. (2011)SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotrop. 11(3): 303-315. http://dx.doi.org/10.1590/S1676-06032011000300025
http://dx.doi.org/10.1590/S1676-06032011... , Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... , Bartozek et al. (2013)BARTOZEK, E.C.R., BUENO, N.C., LUDWIG, T.A.V., TREMARIN, P.I., NARDELLI, M.S. & ROCHA, A.C.R. 2013. Diatoms (Bacillariophyceae) of Iguaçu National Park, Foz do Iguaçu, Brazil. Acta Bot. Bras. 27(1): 108-123. http://dx.doi.org/10.1590/S0102-33062013000100012.
http://dx.doi.org/10.1590/S0102-33062013... . Sometimes cited as Eunotia curvata (Kützing) Lagerstedt var. curvata and as Eunotia lunaris (Ehrenberg) Grunow var. lunaris (Tremarin et al. 2009TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107.).

Taxonomic remarks: Eunotia bilunaris is a very common periphytic species, broadly distributed in the state of Paraná, and frequently registered in Europe, Africa, Asia, North and South America (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Bibl. Diatomol. 64: 1-302.). According to Lange-Bertalot et al. (2011)LANGE-BERTALOT, H., BAK, M., WITKOWSKI, A. & TAGLIAVENTI, N. 2011. Eunotia and some related genera. In Diatoms of Europe (H. Lange-Bertalot ed). Gantner Verlag K.G., Ruggell, 747 p., the species have a heterogeneous concept and a confusing taxonomy due to their wide morphological variability, mostly related to shape and dimensions. Specimens with uncommon morphology are common and have already been formally described as infraspecific taxa. The material analysed showed a wide morphological and metric variation of the valves, corroborating with the observations of Krammer & Lange-Bertalot (1991)KRAMMER, K. & LANGE-BERTALOT, H. 1991. Bacillariophyceae. 3 Teil: Centrales, Fragilariaceae, Eunotiaceae. In Süsswasser-Flora von Mitteleuropa 2/3 (H. Ettl, J. Gerloff, H. Heynig & D. Mollenhauer, eds). Gustav Fischer Verlag, Stuttgart, Jena, pp. 1-576. and Tavares & Valente-Moreira (2000)TAVARES, B. & VALENTE-MOREIRA, I.M. 2000. Diatomoflórula do lago de Cascavel, município de Cascavel, estado do Paraná, Brasil. Hoehnea 27(1): 1-24..

Eunotia botulitropica C.E. Wetzel & L.F. Costa. In: Costa et al., Bibliotheca Diatomologica 64: 14, pl. 58, figs 11‒46, pl. 59, figs 1‒3, pl. 61, figs 1‒3, 2017.

Figures 2p‒2t, 4d‒4f.

Frustule rhomboid in lateral view. Valves dorsiventral, sometimes heteropolar, 11.1‒22.5 µm long and 2.5‒3.7 µm wide. Dorsal margin convex, ventral margin straight to slightly concave. Apices rounded to obtusely rounded . Terminal nodules near the apices. Distal raphe end curved onto the valve face. One small rimoportula per valve, near the apex. Striae parallel, 14‒19 in 10 µm in the middle region of the valve. Areolae rounded, not visible in LM. Cingulum composed of four open bands perforated by one row of pores.

Frequency of occurrence: common (Table 3).

Paraná State citations: cited as E. intermedia (Krasske ex Hustedt) Nörpel & Lange-Bertalot) in Tremarin et al. (2008, fig. 28)TREMARIN, P.I., LUDWIG, T.A.V. & MOREIRA-FILHO, H. 2008. Eunotia Ehrenberg (Bacillariophyceae) do rio Guaraguaçu, litoral do Paraná, Brasil. Acta Bot. Bras. 22: 845-867. https://doi.org/10.1590/S0102-33062008000300020
https://doi.org/10.1590/S0102-3306200800... .

Taxonomic remarks: Eunotia botulitropica was recently described based on samples collected in reservoirs from São Paulo state. According to Costa et al. (2017)COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Bibl. Diatomol. 64: 1-302., E. botulitropica differs from E. botuliformis Wild, Nörpel & Lange-Bertalot by its “narrower valve, lower striae density, rounded and more tapered ends” (Lange-Bertalot et al. 2011LANGE-BERTALOT, H., BAK, M., WITKOWSKI, A. & TAGLIAVENTI, N. 2011. Eunotia and some related genera. In Diatoms of Europe (H. Lange-Bertalot ed). Gantner Verlag K.G., Ruggell, 747 p.). However, the measurements and number of striae overlap, and E. botuliformis can be separated by the parallel valvar margins and the regular distribution of the striae along the valve. Eunotia botulitropica shows rhomboid girdle view, resembling E. rhomboidea Hustedt, but the latter is clearly a heteropolar species and presents larger valves (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Bibl. Diatomol. 64: 1-302.).

Eunotia caniculoides Favaretto, Tremarin, T.Ludwig & Bueno sp. nov.

Figures 2k‒2o, 5a‒5d.

Valves dorsiventral, 30.0‒58.5 µm long and 3.5‒4.9 µm wide. Dorsal margin slightly convex, to almost straight in the larger valves; ventral margin straight to subtly concave. Apices acutely rounded, nose-like, quite protracted from the main body, deflected to ventral side. Pseudosepta in the valve ends. Terminal nodules ventral, somewhat apart from the apices. Distal raphe ends simple, not reaching the valve center. Raphe fissure obliquely curved toward ventral mantle, with proximal ends dilated in pore. One small rimoportula per valve, at the center of the apex. Striae parallel to radiate, denser near the apices, 10‒14 in 10 µm in the middle region of the valve. Areolae round, 38‒40 in 10 µm, not visible in LM. Cingulum composed of four open bands perforated by a single linear row of pores. On the mantle, at the middle of raphe branch, 3 areolae between valve face margin and raphe fissure; 2 to 3 areolae between the raphe branch and lower mantle margin.

Holotype (here designated): BRAZIL, Paraná: São Miguel do Iguaçu, Tenente Gualberto stream, 20 september 2012, L.C. Servat (holotype UNOPA 3943!, depicted in Figure 2n.

Etymology: The epithet refers to the general similarities to Eunotia caniculaFurey, Lowe & Johansen (2011: 57, pl. 30, figs. 39-46)FUREY, P.C, LOWE, R.L. & JOHANSEN, R.J. 2011. Eunotia Ehrenberg (Bacillariophyta) of the Great Smoky Mountains National Park, USA. Biblioth. Diatomol. 56:1-133..

Frequency of occurrence: constant (Table 3).

Taxonomic remarks: Eunotia canicula Furey, Lowe & Johansen is similar to E. caniculoides, but the valve outline and ends shape are quite different. Eunotia canicula has dorsal margin more convex and higher striae density (14-15 in 10 µm). E. caniculoides shows longer protracted ends when compared to E. canicula (Furey et al. 2011FUREY, P. 2011. Eunotia rhomboidea. Diatoms of the United States. Retrieved March 21, 2017, from http://westerndiatoms.colorado.edu/taxa/species/eunotia_rhomboidea.
http://westerndiatoms.colorado.edu/taxa/... ). Fontana & Bicudo (2012)FONTANA, L. & BICUDO, D.C. 2012. Biodiversidade e distribuição das diatomáceas (Bacillariophyceae) de sedimentos superficiais nos reservatórios em cascata do rio Paranapanema (SP/PR, Brasil). Hoehnea 39: 587-612. found E. canicula in the Paranapanema river watershed, state of São Paulo, but the population is clearly distinct from E. caniculoides, and the striae density are even much higher (16‒22/10 µm).

Eunotia caniculoides is similar by the valvar contour and nose-like apices to E. intricans Lange-Bertalot & Metzeltin, described from a lake in Panamá (Lange-Bertalot & Metzeltin 2009LANGE-BERTALOT, H. & METZELTIN, D. 2009. A dystrophic mountain lake in Panamá - hot spot of new and rare neotropical diatoms. Beihefte Nova Hedwigia 135: 137-165.), and to E. sioliopsis Moser, Lange-Betalot & Metzeltin, proposed based on samples collected in New Caledonia. E. intricans has similar dimensions (length 17‒48 µm, width 4.0‒5.0 µm) and striae density (11‒13 in 10 µm) (Table 2) but the apices are more rounded, less protracted, and not flexed to ventral side as in E. caniculoides (Lange-Bertalot & Metzeltin 2009LANGE-BERTALOT, H. & METZELTIN, D. 2009. A dystrophic mountain lake in Panamá - hot spot of new and rare neotropical diatoms. Beihefte Nova Hedwigia 135: 137-165.). E. sioliopsis shows similar dimensions and apices shape, but striae and areolae densities are lower and dorsal margins are more convex (see Table 2). Raphe distal ends in E. sioliopsis and in E. intricans are shorter in valve face and longer in the mantle; and the terminal nodules are less proeminent (Lange-Bertalot & Metzeltin 2009LANGE-BERTALOT, H. & METZELTIN, D. 2009. A dystrophic mountain lake in Panamá - hot spot of new and rare neotropical diatoms. Beihefte Nova Hedwigia 135: 137-165., Moser et al. 1998MOSER, G., LANGE-BERTALOT, H. & METZELTIN, D. 1998. Insel der Endemiten. Geobotanisches Phänomen Neukaledonien. Island of endemics New Caledonia - a geobotanical phenomenon. Bibl. Diatomol 38:[1]-464, 101 pls.), when compared to E. caniculoides. Also, in E. sioliopsis, the areola number in the middle of the raphe branch in the mantle, between the raphe and the mantle margin is higher (4 to 5) (Moser et al. 1998MOSER, G., LANGE-BERTALOT, H. & METZELTIN, D. 1998. Insel der Endemiten. Geobotanisches Phänomen Neukaledonien. Island of endemics New Caledonia - a geobotanical phenomenon. Bibl. Diatomol 38:[1]-464, 101 pls.), and the stability of this character in the epitheca had been reported to the genus by Mayama (2001)MAYAMA, S. 2001. Valuable taxonomic characters in the valve mantle and girdle of some Eunotia species. In Lange-Bertalot-Festschrift: Studies on Diatoms (R. Jahn, J.P. Kociolek, A. Witkowski & P. Compère, eds.) Gantner Verlag K.G., Ruggell, p. 119‒130..

Morphometric data and morphological features of closer species are compared in Table 2. Eunotia caniculoides occurred regularly along the sampling period, except in February and November.

Eunotia desmogonioides Metzeltin & Lange-Bertalot. In: Lange-Bertalot, H. (ed.), Iconographia Diatomologica 11: pl. 5, figs 1‒7, pl. 6: figs 1‒4, 2002.

Figures 2ad‒2ae, 6a‒6c.

Valves linear, sometimes sinuous, 129.9‒177.7 µm long and 4.7‒6.5 µm wide. Dorsal margin slightly convex, ventral margin almost straight. Apices capitate-rounded. Terminal nodules in the apices. Distal raphe end strongly curved onto the valve face. One rimoportula per valve, near the apex. Striae parallel, 14‒15 in 10 µm in the middle region of the valve. Areolae rounded, not visible in LM. Cingulum composed of four to five open bands perforated by rows of pores.

Frequency of occurrence: common (Table 3).

Paraná State citations: Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... , Silva-Lehmkuhl et al. (2019)SILVA-LEHMKUHL, A.M., TREMARIN, P.I., VERCELINO, I.S. & LUDWIG, T.A.V. 2019. Periphytic diatoms from na oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil. Biota Neotrop. 19(2): e20180568. https://doi.org/10.1590/1676-0611-bn-2018-0568.
https://doi.org/10.1590/1676-0611-bn-201... ; cited as Eunotia rabenhorstiana (Grunow) Hustedt): Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107..

Taxonomic remarks: Eunotia rabenhorstiana (Grunow) Hustedt resembles E. desmogonioides, but differs by the terminal nodules more distant from the apices, by the shorter raphe fissures in the valve face, by the presence of rimoportula at two valve poles, and marginal spines (Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical Diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 5: 1-220., 2002).

Eunotia georgii Metzeltin & Lange-Bertalot. In: Lange-Bertalot, H. (ed.), Iconographia Diatomologica 5, p. 61-62; pl. 41, fig. 1-7, pl. 42, fig. 7-8, 1998.

Figure 2z.

Valves arched, 76.2 µm long and 7.7 µm wide. Dorsal margin convex with twelve undulations, ventral margin concave. Apices obtusely rounded. Terminal nodules near the apices. Striae parallel, denser near the apices, 12 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: rare (Table 3).

Paraná State citation: first record.

Taxonomic remarks: E. georgii resembles E. muelleri Hustedt, but the latter distinguishes by the wider and more rounded ends, nodules closer to the ends and lower number of dorsal undulations. Metzeltin & Lange-Bertalot (1998)METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical Diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 5: 1-220. stated that the terminal raphe fissure of E. muelleri extends along the valvar face reaching the dorsal margin and might be an important feature to analyse.

Eunotia guianensis (Ehrenberg) De Toni, Syll. Alg. 2: 792, 1892.

Basionym: Himantidium guianense Ehrenberg, Abh. Königl. Akad. Wiss. Berlin: 417, 2/1, fig. 4, (1841) 1843.

Figures 3a‒3b, 5e.

Valves subtly arched, 31.5‒73.1 µm long and 10.2‒12.7 µm wide. Dorsal margin convex, with two undulations; ventral margin concave. Apices attenuate to acutely rounded, slighly deflected to the dorsal side. Terminal nodules near the apices. Distal raphe end curved onto the valve face, almost reaching the dorsal margin. Rimoportula not visible in LM. Striae parallel to radiate, not equidistant, denser near the apices, 7‒12 in 10 µm in the middle region of the valve. Areolae rounded, 15‒18 in 10 µm. Cingulum composed of six open bands perforated by several rows of pores.

Frequency of occurrence: common (Table 3).

Paraná State citation: first record.

Taxonomic remarks: the smaller valves of Eunotia guianensis resemble E. pileus Ehrenberg and E. ventriosa var. brevis (Patrick) Metzeltin & Lange-Bertalot. E. pileus has more rounded ends and terminal raphe fissures straight. The population analyzed here is similar to Eunotia guianensis registered by Metzeltin & Lange-Bertalot (1998:286, fig.26:1-7)METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical Diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 5: 1-220. in “Brasilien, Lago Calado”. Registered before as part of E. didyma Hustedt ex Zimmermann population illustrated by Bicudo et al. (1995, fig. 24)BICUDO, D.C., DE-LAMONICA-FREIRE, E., FIGUEIREDO, D.M. & LIMA, D. 1995. Ficoflórula do pantanal de Mato Grosso, Brasil: Centrales e Eunotiaceae (Bacillariophyceae). Hoehnea 22(1/2): 165-182..

Eunotia juettnerae Lange-Bertalot. In: Lange-Bertalot (ed.), Diatoms of Europe 6: 127, pl. 26, figs 1‒17, pl. 27, figs 1‒6, 2011

Figures 3c‒3f, 6d.

Valves arcuate, gradually tapering towards the apices, 51.7‒121.9 µm long and 2.4‒3.7 µm wide. Dorsal margin convex, ventral margin concave. Apices rounded, slightly deflected to dorsal side. Distal raphe fissure curved extending to the middle of the valve. Striae parallel, denser near the apices, 15‒19 in 10 µm in the middle region of the valve. Areolae rounded, ca. 50 in 10 µm. Rimoportula and areolae not visible in LM.

Frequency of occurrence: common (Table 3).

Paraná State citation: first record.

Taxonomic remarks: The studied population of Eunotia juettnerae has morphology and measurements (20.9‒99.7 µm long, 2.5‒3.1 µm wide, 17‒20 striae in 10 µm) similar to those recorded in specimens from southeastern Brazil observed by Costa et al. (2017)COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Bibl. Diatomol. 64: 1-302.. Eunotia naegelii has narrower valves (1.5‒3.0 µm) and higher striae density (17‒27 in 10 µm) and E. bilunaris differs on broader valves (3.5‒5.5 µm) and lower striae density (13‒17 in 10 µm) (Lange-Bertalot et al. 2011).

Eunotia karenae Metzeltin & Lange-Bertalot. In: Lange-Bertalot (ed.), Iconographia Diatomologica 18: 105, pl. 48, figs 1‒4, 2007.

Figures 2aa‒2ac.

Valves arched, 118.3‒148.6 µm long and 6.2‒7.6 µm wide. Dorsal margin convex, ventral margin concave. Apices subcapitate, slightly deflected to the dorsal side. Terminal nodules thickened, near the apices. One rimoportula per valve, near the apex. Striae parallel, denser near the apices, 10‒12 in 10 µm in the middle region of the valve. Areolae visible in LM, 23‒26 in 10 µm.

Frequency of occurrence: common (Table 3).

Paraná State citation: first record.

Taxonomic remarks: The overlapped length measure and valve contour of the neotropical E. karenae (length: 128‒200 µm) and the similar E. glacialifalsa Lange-Bertalot (length: 60‒150 µm) represent a difficulty to separate both. E. glacialifalsa, a holartic species, is narrower (5‒6 µm), and has lower striae density (8.5‒10 in 10 µm), according to (Metzeltin & Lange-Bertalot et al. 2007METZELTIN, D. & LANGE-BERTALOT, H. 2007. Tropical Diatoms of south America II. Special remarks on biogeographic disjunction. In Iconographia Diatomologica, Annotated Diatom Monographs.(H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 18: 1-1876.). Eunotia glacialis F.Meister has wider valves (7‒12 µm) and E. glacispinosa Lange-Bertalot & Cantonati possess polar spines (Lange-Bertalot 2011CANTONATI, M. & LANGE-BERTALOT, H. 2011. Diatom monitors of close-to-pristine, very-low alkalinity habitats: three new Eunotia species from springs in Nature Parks of the south-eastern Alps. J. Limnol. 70: 209-221. https://doi.org/10.4081/jlimnol.2011.209.
https://doi.org/10.4081/jlimnol.2011.209... ), characteristics that distinguish them from E. karenae.

Eunotia longicamelus L.F.Costa, D.C.Bicudo & C.E.Wetzel, Bibliotheca Diatomologica 64: 32, pl. 73, figs 1‒17, pl. 74, figs 1‒8, pl. 75, figs 1‒5, pl. 76, figs 1‒4, 2017.

Figures 2u‒2y, 5f.

Valves arched, 22.6‒73.5 µm long and 5.0‒9.6 µm wide. Dorsal margin convex, with two to four undulations; ventral margin concave. Apices rostrate to subcapitate, slightly deflected to the dorsal side. Terminal nodules in the apices. Distal raphe end curved onto the valve face, reaching the dorsal margin. Striae parallel to radiate, denser near the apices, 8‒15 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM. Cingulum composed of six open bands perforated by several rows of pores.

Frequency of occurrence: constant (Table 3).

Paraná State citations: Silva-Lehmkuhl et al. (2019)SILVA-LEHMKUHL, A.M., TREMARIN, P.I., VERCELINO, I.S. & LUDWIG, T.A.V. 2019. Periphytic diatoms from na oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil. Biota Neotrop. 19(2): e20180568. https://doi.org/10.1590/1676-0611-bn-2018-0568.
https://doi.org/10.1590/1676-0611-bn-201... ; cited as E. camelus var. denticulata Grunow in Moreira-Filho & Kutner (1962)MOREIRA-FILHO, H. & KUTNER, M.B. 1962. Contribuição para o estudo das diatomáceas do manguezal de Alexandra, Estado do Paraná. Bol. Univ. Fed. Paraná 4: 1-36.; cited as E. camelus in Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Bertolli et al. (2010)BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24: 1065-1081. https://doi.org/10.1590/S0102-33062010000400022
https://doi.org/10.1590/S0102-3306201000... , Faria et al. (2010)FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales e Gomphonema Ehrenberg. Biota Neotrop. (10)3: 415-527. http://dx.doi.org/10.1590/S1676-06032010000300035.
http://dx.doi.org/10.1590/S1676-06032010... , Silva et al. (2010)SILVA, A.M., LUDWIG, T.A.V., TREMARIN, P.I. & VERCELINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Bot. Bras. 24(4): 997-1016. https://doi.org/10.1590/S0102-33062010000400015.
https://doi.org/10.1590/S0102-3306201000... , Santos et al. (2011)SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotrop. 11(3): 303-315. http://dx.doi.org/10.1590/S1676-06032011000300025
http://dx.doi.org/10.1590/S1676-06032011... , Bartozek et al. (2013)BARTOZEK, E.C.R., BUENO, N.C., LUDWIG, T.A.V., TREMARIN, P.I., NARDELLI, M.S. & ROCHA, A.C.R. 2013. Diatoms (Bacillariophyceae) of Iguaçu National Park, Foz do Iguaçu, Brazil. Acta Bot. Bras. 27(1): 108-123. http://dx.doi.org/10.1590/S0102-33062013000100012.
http://dx.doi.org/10.1590/S0102-33062013... , Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... .

Taxonomic remarks:Eunotia longicamelus is easily separated from E. camelus Ehrenberg bydorsal margin with two to four undulations and less concconcave ventral margin. Eunotia camelus has two evident undulations subdivided into two more smooth ones, and ventral margin more concave (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Bibl. Diatomol. 64: 1-302.). The specimen shown in Figure 2y slightly differs from the others (figs 2u-2x) in the sub-capitate apices and irregular striae density pattern. Although similar to Eunotia karveerensis (Gandhi) Gluschenko & Kulikovskiy (= E. camelus var. karveerensis Gandhi) (Glushchenko & Kulikovskiy 2017GLUSHCHENKO, A.M. & KULIKOVSKIY, M.S. 2017. Taxonomy and distribution of Eunotia camelus (Eunotiaceae, Bacillariophyceae) infraspecific taxa from waterbodies of South-East Asia. Botanicheskii Zhurnal. 102: 329-338.), the valves are much more curved and narrower (6-7 µm and 4.5-5.5 µm in the humps) than E. longicamelus. The authors registered a morphologically diverse population occurring in southeast Asia, western India and Ceylon.

Eunotia meridiana Metzeltin & Lange-Bertalot. In: Lange-Bertalot (ed.), Iconographia Diatomologica 5: 67, pl. 59, figs 7‒10, 1998.

Figures 3g‒3j.

Valves subtly arched, 14.7‒37.7 µm long and 3.7‒5.4 µm wide. Dorsal margin convex, ventral margin linear to slightly concave. Apices attenuate-rounded. Terminal nodules in the ventral margins. Striae parallel to radiate, denser near the apices, 14‒17 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: common (Table 3).

Paraná State citations:Tremarin et al. (2008TREMARIN, P.I., LUDWIG, T.A.V. & MOREIRA-FILHO, H. 2008. Eunotia Ehrenberg (Bacillariophyceae) do rio Guaraguaçu, litoral do Paraná, Brasil. Acta Bot. Bras. 22: 845-867. https://doi.org/10.1590/S0102-33062008000300020
https://doi.org/10.1590/S0102-3306200800... , 2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Santos et al. (2011)SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotrop. 11(3): 303-315. http://dx.doi.org/10.1590/S1676-06032011000300025
http://dx.doi.org/10.1590/S1676-06032011... , Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... .

Eunotia minor (Kützing) Grunow in Van Heurck, Syn. Diat. Belg., pl. 33: figs 20, 21, 1881.

Figure 3k.

Valves dorsiventral, 23.5‒59.0 µm long and 4.0‒5.2 µm wide. Dorsal margin straight, slightly undulate; ventral margin straight to subtly concave. Apices nose-like. Terminal nodules near the apices. Striae parallel to radiate, denser near the apices, 12‒17 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: common (Table 3).

Paraná State citations: Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Santos et al. (2011)SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotrop. 11(3): 303-315. http://dx.doi.org/10.1590/S1676-06032011000300025
http://dx.doi.org/10.1590/S1676-06032011... , Silva et al. (2010SILVA, A.M., LUDWIG, T.A.V., TREMARIN, P.I. & VERCELINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Bot. Bras. 24(4): 997-1016. https://doi.org/10.1590/S0102-33062010000400015.
https://doi.org/10.1590/S0102-3306201000... , Marra et al. 2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... , Faria et al. (2019)FARIA, D.M., COSTIN, J.C., TREMARIN, P.I. & LUDWIG, T.A.V. 2019. Temporal changes in biological traits of diatom communities in response to an oil spill in a subtropical river. An. Acad. Bras Ciec. 91(2): e20170863. http://dx.doi.org/10.1590/0001-3765201920170863.
http://dx.doi.org/10.1590/0001-376520192... , Silva-Lehmkuhl et al. (2019)SILVA-LEHMKUHL, A.M., TREMARIN, P.I., VERCELINO, I.S. & LUDWIG, T.A.V. 2019. Periphytic diatoms from na oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil. Biota Neotrop. 19(2): e20180568. https://doi.org/10.1590/1676-0611-bn-2018-0568.
https://doi.org/10.1590/1676-0611-bn-201... .

Taxonomic remarks: it is a species with complex taxonomy and we based the identification on Lange-Bertalot (2011)LANGE-BERTALOT, H., BAK, M., WITKOWSKI, A. & TAGLIAVENTI, N. 2011. Eunotia and some related genera. In Diatoms of Europe (H. Lange-Bertalot ed). Gantner Verlag K.G., Ruggell, 747 p..

Eunotia monodon Ehrenberg, Abh. K. Akad. Wiss. Berlin, p. 414, pl. 2, fig. 7, 1841 (1843).

Figures 3l‒3n.

Valves arched, 44.5‒80.7 µm long and 7.9‒10.8 µm wide. Dorsal margin convex, ventral margin concave. Apices rounded, differentiated from the main body. Terminal nodules in the apices. Striae parallel to radiate, 9‒12 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: common (Table 3).

Paraná State citations: Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... ; cited as E. monodon var. major (W. Smith) Hustedt - Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Procopiak et al. (2006)PROCOPIAK, L.K., FERNANDES, L.F. & MOREIRA-FILHO, H. 2006. Diatomáceas (Bacillariophyta) marinhas e estuarinas do Paraná, Sul do Brasil: lista de espécies com ênfase em espécies nocivas. Biota Neotrop. 6(3) http://www.biotaneotropica.org.br/v6n3/pt/abstract?inventory+bn02306032006
http://www.biotaneotropica.org.br/v6n3/p... , Faria et al. (2010)FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales e Gomphonema Ehrenberg. Biota Neotrop. (10)3: 415-527. http://dx.doi.org/10.1590/S1676-06032010000300035.
http://dx.doi.org/10.1590/S1676-06032010... .

Taxonomic remarks: E. maior (W. Smith) Rabenhorst is easily distinguished from E. monodon by the clearly set off capitate ends and by the more convex dorsal margin, but parallel to the ventral margin. Eunotia monodon usually has dorsal margin more strongly convex and ventral concave, but not parallel, rounded apices, slightly differentiated from the main body (Patrick & Reimer 1966PATRICK, R. & REIMER, C.W. 1966. The diatoms of the United States: exclusive of Alaska and Hawai.1. Monographs 13. Philadelphia: Academy of Natural Sciences.).

Eunotia pileus Ehrenberg, Ber. K. Akad. Wiss. Berlin 1841: 414 , pl. 2/1, fig. 5, 1843.

Figures 3o‒3u.

Valves subtly arched, 24.8‒43.9 µm long and 11.6‒13.1 µm wide. Dorsal margin convex, with two undulations; ventral margin concave. Apices obtusely rounded to cuneate, weakly deflected to the dorsal side. Terminal nodules in the apices. Rimoportula not visible in LM. Striae parallel to radiate, not equidistant, denser near the apices, 7‒10 in 10 µm in the middle region of the valve. Areolae rounded, 15‒19 in 10 µm.

Frequency of occurrence: common (Table 3).

Paraná State citation: first record.

Taxonomic remarks: see Eunotia guianensis for comments.

Eunotia pseudosudetica Metzeltin, Lange-Bertalot & García-Rodríguez var. pseudosudetica. In: Lange-Bertalot (ed.), Iconographia Diatomologica 15: 57, pl. 24, figs 15‒18, 2005.

Figures 3ae‒ag, 6e.

Valves dorsiventral, 27.2‒38.0 µm long and 4.8‒6.6 µm wide. Dorsal margin convex, ventral margin straight to subtly concave. Apices nose-like, differentiated from the main body. Terminal nodules near the apices. Distal raphe end short, obliquely curved onto the valve face. One rimoportula per valve, near the apex. Striae parallel to radiate, denser near the apices, 11‒15 in 10 µm in the middle region of the valve. Areolae rounded, ca. 38 in 10 µm.

Frequency of occurrence: common (Table 3).

Paraná State citations: Bartozek et al. (2013)BARTOZEK, E.C.R., BUENO, N.C., LUDWIG, T.A.V., TREMARIN, P.I., NARDELLI, M.S. & ROCHA, A.C.R. 2013. Diatoms (Bacillariophyceae) of Iguaçu National Park, Foz do Iguaçu, Brazil. Acta Bot. Bras. 27(1): 108-123. http://dx.doi.org/10.1590/S0102-33062013000100012.
http://dx.doi.org/10.1590/S0102-33062013... ,Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... , Silva-Lehmkuhl et al. (2019)SILVA-LEHMKUHL, A.M., TREMARIN, P.I., VERCELINO, I.S. & LUDWIG, T.A.V. 2019. Periphytic diatoms from na oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil. Biota Neotrop. 19(2): e20180568. https://doi.org/10.1590/1676-0611-bn-2018-0568.
https://doi.org/10.1590/1676-0611-bn-201... .

Taxonomic remarks: The population of Eunotia pseudosudetica analyzed here is similar to type material from Uruguay (Metzeltin et al. 2005METZELTIN, D., LANGE-BERTALOT, H. & GARCÍA-RODRÍGUEZ, F. 2005. Diatoms of Uruguay compared with other taxa from South America and elsewhere. In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.). Gantner Verlag K.G., Ruggell, 15: 1-736.) and to southern Brazilian specimens described and illustrated by Cavalcante et al. (2014)CAVALCANTE, K.P., TREMARIN, P.I., CASTRO, E.C., TIBIRIÇÁ, C.E.J.A., WOJCIECHOWSKI, J. & LUDWIG, T.A.V. 2014. Epiphytic Eunotia (Bacillariophyceae) on Podostemum from Santa Catarina, southern Brazil, including new observations on morphology and taxonomy of some rare recorded species. Biota Neotrop. 14(3): 1-12. https://doi.org/10.1590/1676-06032014003414.
https://doi.org/10.1590/1676-06032014003... .

Eunotia pseudosudetica var. rotundata Cavalcante, Tremarin & T. Ludwig. In: Cavalcante et. al., Biota Neotropica 14(3): 10, figs 67‒74, 80‒83, 2014.

Figures 3v‒3y.

Valves dorsiventral, 52.0‒63.3 µm long and 5.0‒6.0 µm wide. Dorsal margin slightly convex, ventral margin subtly concave to almost straight. Apices rounded, subtly nose-like. Terminal nodules near the apices. Striae parallel to radiate, denser near the apices, 11‒16 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: common (Table 3).

Paraná State citation: first record.

Taxonomic remarks: Eunotia pseudosudetica var. rotundata was originally found in macrophyte samples collected in the state of Santa Catarina. The more rounded ends and less pronounced dorsiventrality distinguish this variety from the typical (Cavalcante et al. 2014CAVALCANTE, K.P., TREMARIN, P.I., CASTRO, E.C., TIBIRIÇÁ, C.E.J.A., WOJCIECHOWSKI, J. & LUDWIG, T.A.V. 2014. Epiphytic Eunotia (Bacillariophyceae) on Podostemum from Santa Catarina, southern Brazil, including new observations on morphology and taxonomy of some rare recorded species. Biota Neotrop. 14(3): 1-12. https://doi.org/10.1590/1676-06032014003414.
https://doi.org/10.1590/1676-06032014003... ).

Eunotia rabenhorstii var. monodon Cleve & Grunow. In: Van Heurck, Syn. Diat. Belg., pl. 35, fig. 12B, 1881.

Figures 3z‒3ab.

Valves arched, 17.2‒32.7 µm long and 6.2‒8.5 µm wide. Dorsal margin convex with one undulation in the middle of the valve, ventral margin concave. Apices broadly rounded. Terminal nodules in the apices. Striae parallel to radiate, denser near the apices, 12‒15 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: common (Table 3).

Paraná State citations: Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... , Silva-Lehmkuhl et al. (2019)SILVA-LEHMKUHL, A.M., TREMARIN, P.I., VERCELINO, I.S. & LUDWIG, T.A.V. 2019. Periphytic diatoms from na oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil. Biota Neotrop. 19(2): e20180568. https://doi.org/10.1590/1676-0611-bn-2018-0568.
https://doi.org/10.1590/1676-0611-bn-201... , Faria et al. (2010FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales e Gomphonema Ehrenberg. Biota Neotrop. (10)3: 415-527. http://dx.doi.org/10.1590/S1676-06032010000300035.
http://dx.doi.org/10.1590/S1676-06032010... , 2019)FARIA, D.M., COSTIN, J.C., TREMARIN, P.I. & LUDWIG, T.A.V. 2019. Temporal changes in biological traits of diatom communities in response to an oil spill in a subtropical river. An. Acad. Bras Ciec. 91(2): e20170863. http://dx.doi.org/10.1590/0001-3765201920170863.
http://dx.doi.org/10.1590/0001-376520192... .

Taxonomic remarks: The pronounced dorsal median undulation distinguishes E. rabenhorstii var. monodon from E. rabenhorstii var. triodon characterized by three dorsal undulations (Van Heurck, 1881VAN HEURCK, H. 1881. Synopsis des Diatomées de Belgique. Atlas. Anvers: Ducaju et Cie. pls 31-77.).

Eunotia rabenhorstii var. triodon Cleve & Grunow. In: Van Heurck, Syn. Diat. Belg., pl. 35, fig. 12A, 1881.

Figures 3ac‒3ad, 6f.

Valves slightly arched, 22.9‒32.7 µm long and 6.5‒8.5 µm wide. Dorsal margin convex with three undulations being the median undulation more pronounced than the others; ventral margin concave. Apices broadly rounded. Terminal nodules in the apices. Striae parallel to radiate, denser near the apices, 12‒14 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM. In SEM, 40 areolae in 10 µm.

Frequency of occurrence: constant (Table 3).

Paraná State citations: Tremarin et al. (2009)TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta - Diatomeae) continentais do estado do Paraná. Iheringia. Sér. Bot. 64: 79-107., Bartozek et al. (2013)BARTOZEK, E.C.R., BUENO, N.C., LUDWIG, T.A.V., TREMARIN, P.I., NARDELLI, M.S. & ROCHA, A.C.R. 2013. Diatoms (Bacillariophyceae) of Iguaçu National Park, Foz do Iguaçu, Brazil. Acta Bot. Bras. 27(1): 108-123. http://dx.doi.org/10.1590/S0102-33062013000100012.
http://dx.doi.org/10.1590/S0102-33062013... .

Eunotia sedina Lange-Bertalot, Bak & Witkowski. In: Lange-Bertalot (ed.), Diatoms of Europe 6: 215, pl. 47, figs 1-17, 2011.

Figures 3ah‒3ak.

Valves dorsiventral, 22.1‒40.5 µm long and 4.7‒5.5 µm wide. Dorsal margin convex, ventral margin straight to slightly concave. Apices rounded, subtly nose-like, undifferentiated to the main body. Terminal nodules near the apices. Striae parallel to radiate, denser near the apices, 12‒14 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: common (Table 3).

Paraná State citation: first record.

Taxonomic remarks: the analyzed population was similar to that described by Lange-Bertalot et al. (2011)LANGE-BERTALOT, H., BAK, M., WITKOWSKI, A. & TAGLIAVENTI, N. 2011. Eunotia and some related genera. In Diatoms of Europe (H. Lange-Bertalot ed). Gantner Verlag K.G., Ruggell, 747 p.. E. sedina resembles Eunotia sioliopsis Moser, Lange-Bertalot & Metzeltin, but the later differs by narrower valves (length 20‒40 µm, width 3.5-4.5 µm) and higher striae density (16‒17 in 10 µm) (Moser et al. 1998MOSER, G., LANGE-BERTALOT, H. & METZELTIN, D. 1998. Insel der Endemiten. Geobotanisches Phänomen Neukaledonien. Island of endemics New Caledonia - a geobotanical phenomenon. Bibl. Diatomol 38:[1]-464, 101 pls.).

Eunotia tropico-arcus Metzeltin & Lange-Bertalot. In: Lange-Bertalot (ed.), Iconographia Diatomologica 18: 123, pl. 74, figs 1‒10, 2007.

Figures 3al‒3an.

Valves dorsiventral, 34.3‒56.1 µm long and 7.6‒8.5 µm wide. Dorsal margin convex with a median depression; ventral margin slightly concave. Apices truncate, differentiated to the main body. Terminal nodules in the apices. Striae parallel to radiate, denser near the apices, 11‒12 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: sporadic.

Paraná State citation: first record.

Taxonomic remarks: Eunotia tropico-arcus resembles E. bidens Ehrenberg, E. praerupta Ehrenberg and E. arcus Ehrenberg. However, E. bidens has more pronounced dorsal median depression and E. praerupta has dorsal margin strongly convex and higher valve width (10‒18 µm) (Metzeltin & Lange-Bertalot 2007METZELTIN, D. & LANGE-BERTALOT, H. 2007. Tropical Diatoms of south America II. Special remarks on biogeographic disjunction. In Iconographia Diatomologica, Annotated Diatom Monographs.(H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 18: 1-1876., Lange-Bertalot et al. 2011LANGE-BERTALOT, H., BAK, M., WITKOWSKI, A. & TAGLIAVENTI, N. 2011. Eunotia and some related genera. In Diatoms of Europe (H. Lange-Bertalot ed). Gantner Verlag K.G., Ruggell, 747 p.). Finally, E. arcus differs in having more arched valves, concave ventral margin and wider apices (Metzeltin & Lange-Bertalot 2007METZELTIN, D. & LANGE-BERTALOT, H. 2007. Tropical Diatoms of south America II. Special remarks on biogeographic disjunction. In Iconographia Diatomologica, Annotated Diatom Monographs.(H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 18: 1-1876.).

Eunotia yanomami Metzeltin & Lange-Bertalot. In: Lange-Bertalot (ed.), Iconographia Diatomologica 5: 86, pl. 34, figs 1‒6, pl. 35, figs 1‒6, pl. 36, figs 1‒13, pl. 37, figs 7‒8, 1998.

Figure 3ao.

Valves arched, 67.0‒95.3 µm long and 10.8‒13.2 µm wide. Dorsal margin convex with two undulations; ventral margin concave. Apices cuneate, rounded. Terminal nodules near the apices. Striae parallel to radiate, denser near the apices, 15‒16 in 10 µm in the middle region of the valve. Rimoportula and areolae not visible in LM.

Frequency of occurrence: sporadic (Table 3).

Paraná State citations: Marra et al. (2016)MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... , Silva-Lehmkuhl et al. (2019); cited as Eunotia zygodon Ehrenberg in Tremarin et al. (2008)TREMARIN, P.I., LUDWIG, T.A.V. & MOREIRA-FILHO, H. 2008. Eunotia Ehrenberg (Bacillariophyceae) do rio Guaraguaçu, litoral do Paraná, Brasil. Acta Bot. Bras. 22: 845-867. https://doi.org/10.1590/S0102-33062008000300020
https://doi.org/10.1590/S0102-3306200800... .

Taxonomic remarks: Metzeltin & Lange-Bertalot (1998)METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical Diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 5: 1-220. described E. yanomami based on Brazilian samples. This species resembles E. zygodon Ehrenberg, however, E. zygodon has a trilobate terminal nodule (Patrick & Reimer 1966PATRICK, R. & REIMER, C.W. 1966. The diatoms of the United States: exclusive of Alaska and Hawai.1. Monographs 13. Philadelphia: Academy of Natural Sciences.) and smaller valves (lectotype: length 53.3 µm and width 10 µm) (Reichardt 1995REICHARDT, E. 1995. Die Diatomeen (Bacillariophyceae) in Ehrenbergs Material von Cayenne, Guayana Gallica (1843). In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 1: 1-49.). Ferrari et al. (2007)FERRARI, F., PROCOPIAK, L.K., ALENCAR, Y.B. & LUDWIG, T.A.V. 2007. Eunotiaceae (Bacillariophyceae) em igarapés da Amazônia Central, Manaus e Presidente Figueiredo, Brasil. Acta Amaz. 37:1-16. http://dx.doi.org/10.1590/S0044-59672007000100001.
http://dx.doi.org/10.1590/S0044-59672007... commented that further studies would be needed in order to conclude on the best distinguishing features between the two species.

The more common taxa in the studied river, occurring in at least 50% of the samples, were: E. bilunaris, E. ambivalens, E. longicamelus, E. karenae, E. minor, E. pseudosudetica var. rotundata, E. monodon, E. juettnerae, E. pileus, E. rabenhorstii var. monodon, E. rabenhorstii var. triodon, E. botulitropica and E. sedina. 66.6% of identified species were widely distributed in the study area and considered of common occurrence, 19.04% were constant, 9.52% were sporadic and 4.76% were rare. In general, the high frequencies of occurrence of the periphytic Eunotia community were in the spring period (76%) and in October (71%).

Discussion

The number of taxa found in the present study (21) can be considered high when compared to Eunotia studies carried out in other Brazilian regions that used a similar methodology, obtaining samples by squeezing an aquatic macrophyte. We highlight Ludwig & Valente-Moreira (1989)LUDWIG, T.A.L. & VALENTE-MOREIRA, I.M. 1989. Contribuição ao conhecimento da diatomoflórula do parque regional do Iguaçu, Curitiba, Paraná, Brasil: I. Eunotiaceae (Bacillariophyceae). Arq. Biol. Tecnol. 32: 543-560. that identified 24 Eunotia and Santos et al. (2011)SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotrop. 11(3): 303-315. http://dx.doi.org/10.1590/S1676-06032011000300025
http://dx.doi.org/10.1590/S1676-06032011... with 18 species. Other studies about diatom flora based on samples collected in the state of Paraná included 44 taxa (Tremarin et al. 2008TREMARIN, P.I., LUDWIG, T.A.V. & MOREIRA-FILHO, H. 2008. Eunotia Ehrenberg (Bacillariophyceae) do rio Guaraguaçu, litoral do Paraná, Brasil. Acta Bot. Bras. 22: 845-867. https://doi.org/10.1590/S0102-33062008000300020
https://doi.org/10.1590/S0102-3306200800... ), 16 taxa (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A.V. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biota Neotrop. 16(4) e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200.
http://dx.doi.org/10.1590/1676-0611-BN-2... ), 13 taxa (Bichoff et al. 2016BICHOFF, A., OSORIO, N.C., DUNCK, B. & RODRIGUES, L. (2016). Periphytic algae in a floodplain lake and river under low water conditions. Biota Neotrop. 16(3): e20160159. http://dx.doi.org/10.1590/1676-0611-BN-2016-0159
http://dx.doi.org/10.1590/1676-0611-BN-2... ), 10 taxa (Fürstenberger & Valente-Moreira 2000FÜRSTENBERGER, C. & VALENTE-MOREIRA, I.M. 2000. Diatomáceas (Bacillariophyta) perifíticas da lagoa Tarumã, Ponta Grossa, Paraná, Brasil. Insula 29: 117-134.), and 8 taxa (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24: 1065-1081. https://doi.org/10.1590/S0102-33062010000400022
https://doi.org/10.1590/S0102-3306201000... ). Bicudo et al. (1995)BICUDO, D.C., DE-LAMONICA-FREIRE, E., FIGUEIREDO, D.M. & LIMA, D. 1995. Ficoflórula do pantanal de Mato Grosso, Brasil: Centrales e Eunotiaceae (Bacillariophyceae). Hoehnea 22(1/2): 165-182. identified 14 taxa on samples from Mato Grosso wetland, Cavalcante et al. (2014)CAVALCANTE, K.P., TREMARIN, P.I., CASTRO, E.C., TIBIRIÇÁ, C.E.J.A., WOJCIECHOWSKI, J. & LUDWIG, T.A.V. 2014. Epiphytic Eunotia (Bacillariophyceae) on Podostemum from Santa Catarina, southern Brazil, including new observations on morphology and taxonomy of some rare recorded species. Biota Neotrop. 14(3): 1-12. https://doi.org/10.1590/1676-06032014003414.
https://doi.org/10.1590/1676-06032014003... found 12 taxa in the state of Santa Catarina, and Ferrari et al. (2007)FERRARI, F., PROCOPIAK, L.K., ALENCAR, Y.B. & LUDWIG, T.A.V. 2007. Eunotiaceae (Bacillariophyceae) em igarapés da Amazônia Central, Manaus e Presidente Figueiredo, Brasil. Acta Amaz. 37:1-16. http://dx.doi.org/10.1590/S0044-59672007000100001.
http://dx.doi.org/10.1590/S0044-59672007... registered 23 species in amazonian water bodies.

Despite numerous investigations of diatom diversity in the state of Paraná, the taxonomic study of the Eunotia based on 12 samples from the Tenente João Gualberto stream resulted in eight new citations for the State, and Eunotia caniculoides was proposed as new. The more common taxa in the studied river, occurring in at least 50% of the samples, were: E. bilunaris, E. ambivalens, E. longicamelus, E. karenae, E. pseudosudetica var. rotundata, E. monodon, E. juettnerae, E. pileus, E. rabenhorstii var. monodon, E. rabenhorstii var. triodon, E. botulitropica and E. sedina. 66.6% of identified species were widely distributed in the study area and considered of common occurrence, 19.04% were constant, 9.52% were sporadic and 4.76% were rare. In general, the high frequencies of occurrence of the periphytic Eunotia community were in the spring period (76%) and in October (71%).

Species of Eunotiaceae are influenced by pH and prefer acidic water (Patrick & Reimer 1966PATRICK, R. & REIMER, C.W. 1966. The diatoms of the United States: exclusive of Alaska and Hawai.1. Monographs 13. Philadelphia: Academy of Natural Sciences., Cantonati & Lange-Bertalot 2011CANTONATI, M. & LANGE-BERTALOT, H. 2011. Diatom monitors of close-to-pristine, very-low alkalinity habitats: three new Eunotia species from springs in Nature Parks of the south-eastern Alps. J. Limnol. 70: 209-221. https://doi.org/10.4081/jlimnol.2011.209.
https://doi.org/10.4081/jlimnol.2011.209... ). They are typical components of the diatom flora from tropical and subtropical areas, frequently associated with acid waters and oligotrophic or dystrophic habitats (Metzeltin & Lange Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical Diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconographia Diatomologica, Annotated Diatom Monographs. (H. Lange-Bertalot, ed.) Gantner Verlag K.G., Ruggell, 5: 1-220., Kociolek & Spaulding 2003KOCIOLEK, J.P. & SPAULDING, S. 2003. Eunotioid and asymmetrical naviculoid diatoms. In Freshwater Algae of North America. Ecology and classification. (J.D. Wehr & R.G.F. Sheath, eds). London, Academic Press Elsevier Science., Furey et al. 2011FUREY, P.C, LOWE, R.L. & JOHANSEN, R.J. 2011. Eunotia Ehrenberg (Bacillariophyta) of the Great Smoky Mountains National Park, USA. Biblioth. Diatomol. 56:1-133., Burliga et al. 2013BURLIGA, A.L., KOCIOLEK, J.P., SALOMONI, S.E. & FIGUEREDO, D. 2013. A new genus and species in the diatom family Eunotiaceae Kützing (Bacillariophyceae) from the Amazonian hydrographic region, Brazil. Phytotaxa 79(2): 47-57. https://doi.org/10.11646/phytotaxa.79.2.1
https://doi.org/10.11646/phytotaxa.79.2.... ). During this study period, the annual pH mean value was predominantly acidic (6.3), an environmental condition that may have favored the species richness of Eunotia. The months of September and October 2012, April and June 2013, with greater richness of Eunotia taxa, showed higher concentrations of dissolved oxygen (11.05 - 22.89 mg.L^-1). Of the months cited, those of 2012 had higher concentrations of TP and NO₃ ^- (0.0198-0.0523 mg.L^-1 and 0.365-0.3775 mg.L^-1 respectively), and lower depth and flow values (0.16-0.21 m and 0.16-0.20 m³.s^-1 respectively).

In conclusion, Eunotia is of great taxonomic complexity and studies are still needed, leading to more complete knowledge of species diversity and distribution in Brazil. In addition, taxonomic knowledge of Eunotia species is essential due to their already known ecological preferences, being useful information for ecological researches aimed at the conservation and management of aquatic environments.

Acknowledgments

The authors acknowledge Coordenação de Aperfeiçoamento Pessoal de Nível Superior (CAPES) for master scholarship to CCRF and PhD scholarship to GM and PIT. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) is thanked for the productivity grant to TAVL (311876/2019-6). We are also grateful to the Centro de Microscopia Eletrônica of Universidade Federal do Paraná for the availability of the scanning electron microscope, and to the Gerpel (Grupo de Pesquisa em Recursos Pesqueiros e Limnologia) by the chemical analyzes of water. Paula C. Ferreira is acknowledged for helping with plates edition and taxa discussion. We thank the reviewers for their careful reading of this manuscript, which significantly improved the text.

References

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