Original Paper

Polar Biology

, Volume 36, Issue 7, pp 957-968

A re-evaluation of morphological characters of the invasive ascidian Corella eumyota reveals two different species at the tip of South America and in the South Shetland Islands, Antarctica

  • Gastón AlurraldeAffiliated withEcología Marina, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba (UNC)Museo Provincial de Ciencias Naturales “Dr. Arturo Umberto Illía” Email author 
  • , Luciana TorreAffiliated withInstituto de Diversidad y Ecología Animal (IDEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Nacional de Córdoba (UNC)
  • , Evangelina SchwindtAffiliated withConsejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro Nacional Patagónico (CENPAT)
  • , Juan C. CastillaAffiliated withNúcleo Milenio de Conservación Marina, F. C. Biológicas, P. Universidad Católica de Chile
  • , Marcos TatiánAffiliated withEcología Marina, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba (UNC)Instituto de Diversidad y Ecología Animal (IDEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)/Universidad Nacional de Córdoba (UNC)

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Abstract

The native solitary ascidian Corella eumyota Traustedt, 1882) is commonly found in the Southern Hemisphere in the cold-temperate waters of the Subantarctic and Antarctic regions. Its recent spread into the Northern Hemisphere throughout the NE Atlantic gave the species the status of invasive. Together with its widespread distribution, reports on its wide variability (several distinct morphological characters, genetic discontinuities and also possible misidentifications) cast doubt on the taxonomic status of different populations of this species. This work, based on the observation, quantification and analysis of specific morphological characters in specimens collected at five different localities of South America and Antarctica, strongly indicates that there are two different species: C. eumyota from South America and Corella antarctica Sluiter, 1905) from Antarctica, which has been till now considered a junior synonym of the former. The species clearly differ in the arrangement of the gonadal ducts, the size of the larvae and the shape of the anus, among other characters. Morphological variation displays a defined, discrete grouping supporting a clear differentiation into two species. This result shows the need for careful inspection of specimens to avoid wrong interpretations in a context of changes of marine biota due to biological invasions.

Keywords

Ascidian Corella eumyota Corella antarctica Morphology Multivariate analysis South America Antarctica Invasions