The Hymenochaetales are an order of fungi in the class Agaricomycetes. The order in its current sense is based on molecular research and not on any unifying morphological characteristics. According to one 2008 estimate, the Hymenochaetales contain around 600 species worldwide,
Taxonomy
History
The order was proposed in 1977 to recognize the family
Hymenochaetaceae at a higher taxonomic rank. As originally conceived, species within the Hymenochaetales had several morphological features in common, notably brown or brownish
basidiocarps (fruit bodies) that turn black in
alkali,
hyphae lacking clamp connections, and the presence (in most species) of characteristic
setae (thick-walled, thorn-shaped
cystidia, visible under a hand lens).
Subsequent ultrastructure research showed that the Hymenochaetales had Dolipore septa with imperforate parenthesomes, whereas most Agaricomycetes have dolipores with perforate parenthesomes.
Current status
Molecular research, based on
cladistic analysis of
DNA sequences, has substantially expanded and redefined the Hymenochaetales, dividing the order into at least six different
clades.
The core clade represents the traditional Hymenochaetaceae, excluding the genera
Coltricia and
Coltriciella; another clade includes the corticioid genera
Lyomyces and
Schizopora (
Schizoporaceae), together with
Coltricia and
Coltriciella as a subclade; a further clade (Repetobasidiaceae) includes agaricoid
Rickenella species,
the clavarioid
Alloclavaria purpurea,
and various corticioid fungi, including the genus
Repetobasidium; the three remaining clades consist of corticioid
Hyphodontia species, corticioid
Kneifiella species, and
poroid Oxyporus species.
Not all the species currently placed within the Hymenochaetales have dolipores with imperforate parenthosomes, so the order lacks any shared morphological characteristics.
File:Inonotus-hispidus01.jpg|
File:Rickenella swartzii - Lindsey 1b.jpg|
File:Schizopora.paradoxa.-.lindsey.jpg|
File:Coltricia perennis 01.JPG|
File:Hyphodontia arguta - Lindsey.jpg|
Habitat and distribution
Most fungi within the order are
saprotrophs of dead wood, but some species within the Hymenochaetaceae can cause rots of living trees. Species of
Coltricia and
Coltriciella are
ectomycorrhizal.
Agaricoid species of
Rickenella and related genera are parasites of mosses and liverworts.
Distribution of the Hymenochaetales is cosmopolitan.
Economic importance
Several wood decay fungi in the genera
Phellinus and
Inonotus sensu lato are pathogenic, causing losses in forestry plantations. Therapeutic properties are claimed for
Inonotus obliquus ("chaga")
and
Phellinus linteus,
both of which are commercially marketed as alternative medicines.
Genera incertae sedis
Several genera in the Hymenochatales are
incertae sedis with respect to familial placement:
External links
