6 Chytridiomycota, Monoblepharidomycota,
and Neocallimastigomycota
MARTHAJ. POWELL^1 ,PETERM. LETCHER^1
CONTENTS
I. Introduction............................... 141
II. Occurrence and Dispersal................. 142
III. Culture and Maintenance................. 146
IV. Phylogenetic Concepts of Zoosporic Fungi 146
V. Identification of Zoospore Ultrastructural
Characters and Character States......... 147
VI. Characterization of Phyla................. 148
A. Chytridiomycota........................ 150- Rhizophydiales ....................... 150
- Chytridiales........................... 156
- Cladochytriales....................... 157
- Lobulomycetales ..................... 158
- Polychytriales ........................ 159
- Spizellomycetales .................... 159
- Rhizophlyctidales .................... 161
8.SynchytriumLineage................. 162
9.Blyttiomyces helicusLineage ........ 162
B. Monoblepharidomycota................ 163
C. Neocallimastigomycota................. 164
VII. Evolution................................... 165
VIII. Conclusions................................ 167
References.................................. 168
I. Introduction
Phylogenetic analyses of molecular sequences
(James et al. 2000 ,2006a,b) have generated
monumental growth in our understanding of
evolutionary relationships among zoosporic
fungi since Barr’s ( 2001 ) review of the morphol-
ogy, life history, and occurrence of Chytridio-
mycota over a decade ago. New understandings
of evolutionary relationships among zoosporic
fungi have sharpened our focus on the value of
zoospore ultrastructural characters in system-
atic analyses (Letcher et al.2008a,c; Simmons
2011 ) and have given us insights into the con-
vergence of thallus features (Letcher et al. 2005 ;
Mozley-Standridge et al. 2009 ) once used as
primary taxonomic characters (Sparrow 1960 ).
Molecular techniques allow us to detect uncul-
tured and unseen chytrids in environmental
samples and to demonstrate that zoosporic
fungi are essentially ubiquitous and abundant
in a wide range of habitats, including temperate
soils and aquatic environments (Chen et al.
2008 ; Lefe`vre et al. 2008 , 2012 ; Lepe`re et al.
2008 ; Miki et al. 2011 ; Monchy et al. 2011 ;
Sime-Ngando et al. 2011 ) as well as especially
stressful environments such as anoxic deep-sea
cold seeps and hydrothermal vent ecosystems
(LeCalvez et al. 2009 ; Nagahama et al. 2011 ;
Stoeck and Epstein 2003 ), exposed soils at
high elevations (Freeman et al. 2009 ; Schmidt
et al. 2012 ), and soils at Arctic latitudes (Stoeck
et al. 2007 ). A renaissance of interest in zoo-
sporic fungi is occurring because, as basal
members in the evolution of fungi, they hold
the key to reconstructing ancestral forms and
forces that may have driven the evolutionary
radiation of fungi (Amaral Zettler et al. 2001 ;
Stajich et al. 2009 ; Steenkamp et al. 2006 ).
Moreover, their roles as parasites of phyto-
plankton (Bruning et al. 1992 ; Holfeld 2000 )
and amphibians (Longcore et al. 1999 , 2007 ;
Piotrowski et al. 2004 ; Voyles 2011 ) cause con-
cern among conservationists (Bai et al. 2010 ;
Rosenblum et al. 2008 ; Schloegel et al. 2012 ;
Weldon et al. 2004 ); their recognition as key
players in food webs alerts ecologists of their
potential impact on aquatic and terrestrial sus-
tainability (Gleason et al. 2008 ; Kagami et al.(^1) Department of Biological Sciences, The University of Alabama,
Tuscaloosa, AL 35487, USA; e-mail:[email protected].
edu;[email protected]
Systematics and Evolution, 2ndEdition
The Mycota VII Part A
D.J. McLaughlin and J.W. Spatafora (Eds.)
©Springer-Verlag Berlin Heidelberg 2014