NOGUEIRA, I., DUNCK, B. The genus Pinnularia (Bacillariophyta, Pinnulariaceae) from Lago dos Tigres, Britânia, Goiás, Brazil. Biota Neotropica. 16(1): e20150028. http:// dx.doi.org/10.1590/1676-0611- BN-2015-0028 Abstract: Studies of the genus Pinnularia Ehrenb. are only incipient in central-western Brazil, especially in Goiás. Only 20 of the 170 taxa known from Brazil were recorded in this state until now. A taxonomic study of Pinnularia from Lago dos Tigres (Tocantins-Araguaia River Basin) recorded 20 specific and infraspecific taxa, distributed in 17 species, including P. instabilis whose lectotype is designated here. Only P. meridiana var. meridiana was previously recorded in aquatic systems of the state. Eighteen taxa are newly recorded for Goiás, and one is the first record in Brazil. The Pinnularia flora from Lago dos Tigres contains nine taxa in common with the Amazon River Basin flora, and seven other taxa that occur elsewhere in the Paraná River Basin. Resumo: O gênero Pinnularia Ehrenb. é incipientemente estudado na região Centro-Oeste brasileira, especialmente em Goiás. Somente 20 de 170 táxons conhecidos no Brasil foram registrados nesse estado até agora. Nesse estudo, objetivou-se a realizac¸ão de estudos taxonômicos de Pinnularia do Lago dos Tigres (Bacia Tocantins-Araguaia). Vinte táxons em nível específico e infraespecífico, distribuídos em 17 espécies, foram observados e caracterizados aqui, incluindo P. instabilis cujo lectótipo foi designado aqui. Somente P. meridiana var. meridiana foi primeiramente registrada em sistemas aquáticos do estado. Dezoito táxons constituíram citac¸ões pioneiras para o estado de Goiás e um foi o primeiro registro de ocorrência para o Brasil. A flora de Pinnularia do Lago dos Tigres apresentou nove táxons comuns com a Bacia Amazônica e outras sete foram comuns à Bacia do Paraná. Palavras-chave: vale bloqueado, Pinnularia meridian, Pinnularia instabilis, lecotipificac¸ão, Centro-Oeste.
IntroductionThe taxon name Pinnularia was proposed by Ehrenberg (1840a, 1840b) as a subgenus of Navicula Bory. Later, Ehrenberg (1843a, 1843b) used the name at generic level. However, the name Pinnularia was earlier used by Lindley & Hutton (1835) for a genus of fossil high plants. Pinnularia Lindley & Hutton was lesser used than Pinnularia Ehrenb., which was conserved against the first one and it is the correct name to generic level according the International Code for Nomenclature of algae, fungi and plants (ICN, McNeill et al. 2012).Pinnularia is a genus of naviculoid diatoms characterized by valves linear, lanceolate or elliptic, with plane or undulate surfaces (Krammer 2000). Members of this genus usually presented different courses of the internal and external fissure of the raphe; transapically, the valves bear alveolated costal systems, which are simple or partially recovered (Krammer 2000). This genus occurs predominantly in oligotrophic continental waters, with low electrolyte concentration and low pH values (Uherkovich 1984, Metzeltin & Lange-Bertalot 1998, Krammer 2000....