Tursiocola podocnemicola sp. nov., a new epizoic freshwater diatom species from the Rio Negro in the Brazilian Amazon Basin

Abstract

Tursiocola podocnemicola sp. nov. is described from the Amazonian Rio Negro Basin in Brazil where it was found living epizoically on the carapaces of the freshwater turtle Podocnemis erythrocephala Spix. The detailed morphology of this epizoic diatom is examined using both light and scanning electron microscopy and compared with similar species of the genera Tursiocola Holmes, Nagasawa & Takano and Epiphalaina Holmes, Nagasawa & Takano. Specimens of this epizoic diatom belong to the genus Tursiocola, characterized by the presence of extensive pseudosepta, covering part of the apices and continuing along the mantle margin to merge with the stauros, uniseriate striae and two knob-like structures between the internal central raphe endings. However, the new species has a different external raphe structure when compared with all other species described from the mentioned genera, with unilaterally, strongly deflected, proximal raphe endings. The ecology and possible origin of the species on the Amazonian turtle's carapace is briefly discussed.

Keywords:

• Amazon Basin
• Bacillariophyceae
• Brazil
• diatoms
• epizoic algae
• freshwater turtles

Acknowledgements

Financial support for this work was provided by Financiadora de Estudos e Projetos, Ministério da Ciência e Tecnologia, Governo Federal, Brazil (FINEP). C.E. Wetzel thanks the Public Research Centre – Gabriel Lippmann (Belvaux, Luxembourg) for support and the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP – Process n° 07/51360–6) for a PhD grant. We are grateful to the herpetologists Richard Vogt and Rafael Bernhardt [Instituto Nacional de Pesquisas da Amazônia (INPA), Brazil] for capturing the Rio Negro turtles. Alex Ball and the staff of the Electron Microscopy and Mineral Analysis (EMMA) laboratory at the Natural History Museum are thanked for their help with scanning electron microscopy. This study was supported by an EU Synthesys grant to Bart Van de Vijver to visit the National History Museum in London, UK.