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Type: Article
Published: 2014-01-30
Page range: 43–56
Abstract views: 12
PDF downloaded: 1

Transfer of Fragilaria atomus Hust. to the genus Stauroforma (Bacillariophyta) based on observation of type and newly collected material

Programa de Pós-Graduação em Botânica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves nº 9500,Campus do Vale, CEP 91501-970, Porto Alegre, RS, Brazil.
Public Research Centre–Gabriel Lippmann, Department Environment and Agro-biotechnologies (EVA), 41 Rue du Brill, L-4422 Belvaux, Luxembourg
Herbario Criptogámico, Universidad Católica Boliviana San Pablo, Calle M. Márquez esq. Plaza Jorge Trigo s/n, P.O. Box 5381, Cochabamba, Bolivia
Public Research Centre–Gabriel Lippmann, Department Environment and Agro-biotechnologies (EVA), 41 Rue du Brill, L-4422 Belvaux, Luxembourg
Fundação Zoobotânica do Rio Grande do Sul, Museu de Ciências Naturais, Rua Salvador França, 1427, Jardim Botânico, CEP 90690-000, Porto Alegre, RS, Brazil.
araphids Bacillariophyceae Brazil diatoms Fragilaria atomus Hustedt Collection salt marsh South America Stauroforma taxonomy type material

Abstract

Fragilaria atomus was described from a brackish water lagoon in southern Finland and has subsequently been reported from several localities worldwide. However, due to its small size, it can be easily mistaken with other small, morphologically similar araphid diatoms. To clarify the morphological, metric and structural features of the species, lectotype material from BRM (Hustedt’s diatom collection) and specimens from salt marshes in Brazil were studied using light and scanning electron microscopy. Fragilaria atomus is compared to seven morphologically similar taxa belonging to Fragilaria, Stauroforma and Psammoneis. The results revealed that some important features of Fragilaria (discoid closing plates, rimoportulae and spines) are not present in F. atomus. The absence of these structures, together with the opposite striation pattern, round areolae, features of the apical pore field, and reduced or absent sternum, suggest that a transfer of F. atomus to Stauroforma is appropriate. The distribution and ecology of F. atomus is discussed.