Urediniomycetes

Urediniomycetes is a diverse class of fungi that includes several important plant pathogens causing forms of fungal rust. It is the only class in the subdivision Teliomycotina of basidiomycetes.

Characteristics
Urediniomycetes develop no basidiocarp, karyogamy occurs in a thick-walled resting spore (teliospore), and meiosis occurs upon germination of teliospore. They have simple septal pores without membrane caps and disc-like spindle pole bodies. Except for a few species, the basidia are transversally septate. Mannose is the major cell wall carbohydrate, glucose, fucose and rhamnose are the less prevalent neutral sugars and xylose is not present.

Systematics
The class contains approximately 7400 species, distributed among approximately 215 genera, but can be much larger as many cryptic species are recognized. More than 95% of the species and 75% of the genera are placed in the order Uredinales. Due to the rapid accumulation of new data, the classification of Urediniomycetes is still under development. Currently, the class is divided into the orders Agaricostilbales, Atractiellales, Classiculales, Microbotryales, Septobasidiales, Sporidiales and Uredinales. Three subclasses (Urediniomycetidae, Agaricostilbomycetidae and Microbotryomycetidae) have been proposed. An attempt of integrated consensus-classification is presented below:
 * Subclass: Microbotryomycetidae
 * Order: Cryptomycocolacales Oberwinkler & Bauer
 * Family: Cryptomycocolacaceae Oberwinkler & Bauer
 * Order: Heterogastridiales Oberwinkler & Bauer
 * Family: Heterogastridiaceae Oberwinkler & Bauer
 * Order: Leucosporidiales Sampaio, Weiss & Bauer
 * Order: Sporidiobolales Sampaio, Weiss & Bauer
 * Family: Sporidiobolaceae Moore emend. Sampaio, Weiss & Bauer
 * Order: Microbotryales Bauer & Oberwinkler
 * Family: Microbotryaceae Moore
 * Family: Ustilentylomataceae Bauer & Oberwinkler
 * Taxa of the Microbotryomycetidae incertae sedis
 * Family: Krieglsteineraceae Pouzar
 * Family: Camptobasidiaceae Moore
 * Genera: Atractocolax, Bensingtonia, Colacogloea, Kriegeria


 * Subclass: Agaricostilbomycetidae
 * Order: Agaricostilbales Oberwinkler & Bauer
 * Family: Agaricostilbaceae Oberwinkler & Bauer
 * Family: Chionosphaeraceae Oberwinkler & Bandon
 * Taxa of the Agaricostilbomycetidae incertae sedis
 * Genera: Bensingtonia, Kondoa, Kurtzmanomyces, Mycogloea, Sporobolomyces, Sterigmatomyces, Spiculogloea, Zygogloea


 * Subclass: Urediniomycetidae
 * Order: Uredinales Arthur
 * 14 families
 * Order: Septobasidiales Couch ex Donk
 * Family: Septobasidiaceae Maire
 * Family: Pachnocybaceae Oberwinkler & Bauer
 * Order: Platygloeales Moore
 * Taxa of the Urediniomycetidae incertae sedis
 * Family: Eocronartiaceae Jülich
 * Genera: Helicobasidium, Herpobasidium, Insolibasidium, Jola, Platycarpa, Ptechetelium


 * Other groups of uncertain position:
 * Order Atractiellales Oberwinkler & Bandoni
 * Family: Hoehnelomycetaceae Jülich
 * Family: Phleogenaceae Weese
 * Family: Helicogloeaceae Jülich
 * Order: Classiculales Bauer, Begerow, Oberwinkler & Marvanová
 * Family: Classiculaceae Bauer, Begerow, Oberwinkler & Marvanová
 * Order: Cystobasidiales (Bauer & Sampaio, in prep.)