Simonsenia aveniformis sp nov (Bacillariophyceae), molecular phylogeny and systematics of the genus, and a new type of canal raphe system

• Autor(a) principal: Witkowski, Andrzej
• Data de Publicação: 2015
• Outros Autores: Gomes, Ana, Mann, David G., Trobajo, Rosa, Li, Chunlian, Barka, Frederik, Gusev, Evgeniy, Dabek, Przemyslaw, Grzonka, Justyna, Kurzydlowski, Krzysztof J., Zglobicka, Izabela, Harrison, Michael, Boski, T.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/11772
• topic: Diatoms Bacillariophyta; Valve Morphogenesis; Rdna sequences; Lsu Rdna; Nitzschia; Bacillariaceae; Auxosporulation; Lanceolatae; Morphology; Evolution

The genus Simonsenia is reviewed and S. aveniformis described as new for science by light and electron microscopy. The new species originated from estuarine environments in southern Iberia (Atlantic coast) and was isolated into culture. In LM, Simonsenia resembles Nitzschia, with bridges (fibulae) beneath the raphe, which is marginal. It is only electron microscope (EM) examination that reveals the true structure of the raphe system, which consists of a raphe canal raised on a keel (wing), supported by rib like braces (fenestral bars) and tube-like portulae; between the portulae the keel is perforated by open windows (fenestrae). Based on the presence of portulae and a fenestrated keel, Simonsenia has been proposed to be intermediate between Bacillariaceae and Surirellaceae. However, an rbcL phylogeny revealed that Simonsenia belongs firmly in the Bacillariaceae, with which it shares a similar chloroplast arrangement, rather than in the Surirellaceae. Lack of homology between the surirelloid and simonsenioid keels is reflected in subtle differences in the morphology and ontogeny of the portulae and fenestrae. The diversity of Simonsenia has probably been underestimated, particularly in the marine environment.