Get access

Ultrastructural Description of Breviata anathema, N. Gen., N. Sp., the Organism Previously Studied as “Mastigamoeba invertens

Authors

  • GISELLE WALKER,

    1. Department of Zoology, The Natural History Museum, London SW7 5BD, UK
    Search for more papers by this author
    • 1Present address: University Museum of Zoology, Cambridge CB2 3EJ, UK.

  • JOEL B. DACKS,

    1. Department of Zoology, The Natural History Museum, London SW7 5BD, UK
    Search for more papers by this author
    • 2Present address: Department of Biological Sciences, University of Calgary, Alberta T2N 1N4, Canada.

  • T. MARTIN EMBLEY

    1. Department of Zoology, The Natural History Museum, London SW7 5BD, UK
    Search for more papers by this author
    • 3Present address: School of Biology, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK.


Corresponding Author: G. WALKER, University Museum of Zoology, Cambridge CB2 3EJ, UK—Telephone number: +44 1223 336653; e-mail: Gw265@cam.ac.uk

Abstract

ABSTRACT. An understanding of large-scale eukaryotic evolution is beginning to crystallise, as molecular and morphological data demonstrate that eukaryotes fall into six major groups. However, there are several taxa of which the affinities are yet to be resolved, and for which there are only either molecular or morphological data. One of these is the amoeboid flagellate Mastigamoeba invertens. This organism was originally misidentified and studied as a pelobiont using molecular data. We present its first light microscopical and ultrastructural characterisation. We demonstrate that it does not show affinities to the amoebozoan pelobionts, because unlike the pelobionts, it has a double basal body and two flagellar roots, a classical Golgi stack, and a large branching double membrane-bound organelle. Phylogenetic analyses of small subunit ribosomal RNA suggest an affinity with the apusomonads, when a covariotide correction for rate heterogeneity is used. We suggest that previous molecular results have been subject to artefacts from an insufficient correction for rate heterogeneity. We propose a new name for the taxon, Breviata anathema; and the unranked, apomorphy-based name “Breviates” for Breviata and its close relatives.

Ancillary