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Species Boundaries in Gregarine Apicomplexan Parasites: A Case Study-Comparison of Morphometric and Molecular Variability in Lecudina cf. tuzetae (Eugregarinorida, Lecudinidae): SPECIES BOUNDARIES IN GREGARINES

Rueckert, Sonja; Villette, Petra M E H; Leander, Brian S


Petra M E H Villette

Brian S Leander


Trophozoites of gregarine apicomplexans are large feeding cells with diverse morphologies that have played a prominent role in gregarine systematics. The range of variability in trophozoite shapes and sizes can be very high even within a single species depending on developmental stages and host environmental conditions; this makes the delimitation of different species of gregarines based on morphological criteria alone very difficult. Accordingly, comparisons of morphological variability and molecular variability in gregarines are necessary to provide a pragmatic framework for establishing species boundaries within this diverse and poorly understood group of parasites. We investigated the morphological and molecular variability present in the gregarine Lecudina cf. tuzetae from the intestines of Nereis vexillosa (Polychaeta) collected in two different locations in Canada. Three distinct morphotypes of trophozoites were identified and the small subunit (SSU) rDNA was sequenced either from multicell isolates of the same morphotype or from single cells. The aim of this investigation was to determine whether the different morphotypes and localities reflected phylogenetic relatedness as inferred from the SSU rDNA sequence data. Phylogenetic analyses of the SSU rDNA demonstrated that the new sequences did not cluster according to morphotype or locality and instead were intermingled within a strongly supported clade. A comparison of 1,657 bp from 45 new sequences demonstrated divergences between 0% and 3.9%. These data suggest that it is necessary to acquire both morphological and molecular data in order to effectively delimit the “clouds” of variation associated with each gregarine species and to unambiguously reidentify these species in the future

Journal Article Type Article
Online Publication Date May 13, 2011
Publication Date 2011-07
Deposit Date Sep 25, 2013
Print ISSN 1066-5234
Electronic ISSN 1550-7408
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 58
Issue 4
Pages 275-283
Keywords Microbiology
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