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A new oomycete species parasitic in nematodes, Chlamydomyzium dictyuchoides sp. nov.: Developmental biology and phylogenetic studies

Lookup NU author(s): Dr Gordon Beakes, Dr Sally Glockling



This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


The genus Chlamydomyzium is a little studied holocarpic oomycete parasite of nematodes of uncertain phylogenetic and taxonomic position. A new holocarpic species, Chlamydomyzium dictyuchoides, is described which has usually refractile cytoplasm and a dictyuchoid pattern of spore release. This new species infects bacteriotrophic rhabditid nematodes and was isolated from diverse geographical locations. Infection was initiated by zoospore encystment on the host surface and direct penetration of the cuticle. A sparsely branched, constricted, refractile thallus was formed which eventually occupied almost the entire host body cavity, often accompanied by complete dissolution of the host cuticle. Walled primary cysts formed throughout the thallus and each cyst released a single zoospore via an individual exit papillum, leaving a characteristic dictyuchoid wall net behind. At later stages of infection some thalli formed thick-walled stellate resting spores in uniseriate rows. Resting spore formation appeared to be parthenogenetic and was not accompanied by the formation of antheridial compartments. These spores had ooplast-like vacuoles and thick multi-layered walls, both of which suggest they were oospores. The maximum likelihood tree of sequences of the small ribosomal subunit (SSU) gene placed this new isolate in a clade before the main saprolegnialean and peronosporalean lines diverge. A second undescribed Chlamydomyzium sp., which has direct spore release forms a paraphyletic clade, close to C. dictyuchoides and Sapromyces. The fine structure of other documented Chlamydomyzium species was compared, including an undescribed (but sequenced) isolate, SL02, from Japan, Chlamydomyzium anomalum and Chlamydomyzium oviparasiticum. Chlamydomyzium as currently constituted is a paraphyletic genus that is part of a group of phylogenetically problematic early diverging clades that lie close to both the Leptomitales and Rhipidiales. Crown Copyright (C) 2014 Published by Elsevier Ltd on behalf of The British Mycological Society. All rights reserved.

Publication metadata

Author(s): Beakes GW, Glockling SL, James TY

Publication type: Article

Publication status: Published

Journal: Fungal Biology

Year: 2014

Volume: 118

Issue: 7

Pages: 527-543

Print publication date: 01/07/2014

Online publication date: 02/05/2014

Acceptance date: 09/04/2014

Date deposited: 22/10/2014

ISSN (print): 1878-6146

ISSN (electronic): 1878-6162

Publisher: Elsevier


DOI: 10.1016/j.funbio.2014.04.005


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Funder referenceFunder name
Department of Biology, Northern Illinois University
DEB0213076National Science Foundation
F/125/A1Leverhulme Trust