Chytrid Fungi Online

A PEET Project

What are Chytrids?

     Chytrids are zoosporic fungi classified in the phylum Chytridiomycota, which currently includes two classes, Chytridiomycetes and Monoblepharidomycetes. In the Chytridiomycetes there are six orders, each with distinct zoospore architecture: Chytridiales, Spizellomycetales, Rhizophlyctidales, Rhizophydiales, Cladochytriales, and Lobulomycetales (Hibbett et al. 2007). Chytrid fungi are important saprophytes and parasites in both aquatic and terrestrial habitats and have been collected from the arctic to the tropics (reviewed in Powell 1993). They are seemingly ubiquitous biodegraders of refractory materials

The thallus of a chytrid fungus, with a single round sporangium (arrow), grows
between pollen grains (round brown bodies), eventually penetrating the pollen
with its branched tubular rhizoids. The sporangium is 50 micrometers in diameter.

such as chitin, keratin and cellulose, and hence play a role in nutrient recycling. As parasites of aquatic organisms, chytrids may have a role in natural control of populations. Their potential transformational role in aquatic food webs is little studied and newly recognized.

Numerous parasitic chytrids attack the filament of a green alga.

     An especially notorious chytrid is Batrachochytrium dendrobatidis, the first chytrid documented to parasitize vertebrate animals. Discovered and described in the mid 1990s (Longcore et al., 1999), it is considered a primary culprit in the global deaths and mass extinctions of frogs and other amphibians. This chytrid has been reported as a parasite on over 90 species of amphibians

CHYTRID-PEET Co.P.I., Joyce Longcore talks with Undergraduate Researchers at The University of Alabama in June 2003 about how to design investigations of chytrids and her role in the discovery and description of the chytrid parasite of frogs.

     Despite their importance, chytrid fungi are understudied and their biodiversity under explored. To address the need for exploration of chytrid biodiversity and the modernization of their taxonomy, the National Science Foundation is supporting a collaborative CHYTRID-PEET (Partnership in Expanding Expertise in Taxonomy) PROJECT. This collaboration involves three laboratories:
     the Powell laboratory at The University of Alabama,
     the Porter laboratory at The University of Georgia (now retired), and
     the Longcore laboratory at The University of Maine.

      The CHYTRID-PEET collaboration has trained two PhD students at The University of Alabama
[James Chambers (2003) and Peter Letcher (2003)] and a third PhD student [ Sharon Mozley-Standridge (2005)] at The University of Georgia in the systematics and phylogenetics of zoosporic fungi (Order Chytridiales). Current trainees include Scott Wakefield, Rabern Simmons, and Emilie Lefevre.

On our general CHYTRID-PEET website, you will find information about chytrid biogeography and how to isolate, grow and cryopreserve them. In addition there is a photogallery that displays the amazing range of thallus morphologies found among chytrids.

About the CHYTRID PEET at The University of Alabama

     The CHYTRID-PEET Project investigated three of the four clades James et al. (2000) resolved in the Order Chytridiales from analyses of small subunit ribosomal RNA genes (SSU) from representatives of the Phylum Chytridiomycota. Students working in the Powell laboratory, at the University of Alabama, focused on analyses of two of the four clades: the Chytriomyces clade and the Rhizophydium clade. To provide greater resolution of phylogenetic structure in the Phylum Chytridiomycota, our initial studies of 44 chytrids analyzed combined large subunit ribosomal (LSU) and small subunit ribosomal (SSU) gene sequences aligned based on secondary RNA structure. Results of analyses allowed us to construct a statistically better supported phylogenetic framework for the Phylum Chytridiomycota (Chambers 2003).

Summary of phylogenetic reconstruction of relationships between groups in the Phylum Chytridiomycota based on combined SSU and LSU sequences (Maximum Parsimony; Jackknife support values above the lines). The Order Chytridiales (Lacustromyces, Nowakowskiella, Rhizophydium, and Chytriomyces clades) is not monophyletic. Although Rhizophlyctis rosea is sister to the rest of the Order Spizellomycetales, results suggest that the Rhizophlyctis rosea clade may be a separate order from the Spizellomycetales clade.

Molecular analyses indicate that the Phylum Chytridiomycota is not monophyletic. Rather, the order Blastocladiales is most basal, evolving among members of the Zygomycotina. Another monophyletic group includes the "core chytrid orders" of the Chytridiales, Monoblepharidales, Spizellomycetales, and Neocallimastigales.

Tools for Understanding Chytrids

     We are in an exciting period where the classification of chytrids will be totally revised, supplementing a solely morphological-based system (Sparrow 1960) with phylogenetic-based taxa. Exploring the links to the left, you will find additional information from these studies on the Rhizophydium and Chytriomyces clades including:

  • Interactive Chytriomyces key (from the key each species is hyperlinked to descriptions, and descriptions are hyperlinked to illustrations)
  • Interactive key to Karlingiomyces.
  • Characteristics of all described species of Rhizophydium summarized in a spreadsheet database;
  • Geographic distribution of all described species of Rhizophydium summarized in a spreadsheet;
  • A relational database of studied chytrid cultures that can be updated on the web.
  • PowerPoint presentation about chytrid zoospores.
  • PowerPoint presentation about chytrid reproduction.


Barr, D.J.S. 2001. Chytridiomycota. pp. 93-112. In: The Mycota. VIIA Systematics and Evolution. (eds. D.J. McLaughlin, E.G. McLaughlin, P.A. Lemke) Springer-Verlag Berlin.

Chambers, J. 2003. Ribosomal DNA, secondary structure and phylogenetic relationships among the Chytridiomycota. Ph. D. Dissertation. The University of Alabama. 116 pp. August 2003.

James, T. Y., D. Porter, C. A. Leander, R. Vilgalys, and J. E. Longcore 2000. Molecular phylogenetics of the Chytridiomycota support the utility of ultrastructural data in chytrid systematics. Canad. J. Bot. 78: 336-350.

Letcher, P.M. 2003. Systematic analysis of molecular and ultrastructural characters among two clades of zoosporic fungi. Ph.D. Dissertation. The University of Alabama. 149 pp. December 2003.

Longcore, J.E., A.P. Pessier, and K.D. Nichols. 1999. Batrachochytrium denderobatidis gen. et sp. nov., a chytrid pathogenic to amphibians. Mycologia 91: 219-227.

Powell, M. J. 1993. Looking at mycology with a Janus face. A glimpse at Chytridiomycetes in the environment. Mycologia 85: 1-20.

Sparrow, F.K. 1960. Aquatic Phycomycetes. 2nd Rev. Ed. Univ. Michigan Press, Ann Arbor , Michigan .


Funding for this site was provided by the National Science Foundation's program on Partnerships for Enhancing Expertise in Taxonomy (PEET) (DEB-9978094). Any opinions, findings, and conclusions or recommendations expressed in these materials are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the institutions supporting the authors.


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