Dear Friends of the Atlas,
we posted another educational blog:
Enjoy reading!
What happened with Chaetomium?
A comment and update.
The genus Chaetomium is well-known
for its elaborate ascomata, as beautifully illustrated in a series of
publications by X.W. Wang and coworkers (Wang et al. 2016a,b, 2019a,b, 2022). The
genus was described in 1817 by Gustav Kunze and typified with C. globosum.
Members of the genus can easily be recognized by their ascomata covered with long,
often branched or curled hairs. With this characteristic, around 430 names were
introduced, and 270 of these were accepted in modern literature. Species were
identified by the structure of the ascoma wall, ascomatal hairs, asci shape,
ascospore germ pores, and the growth temperature. The genus Chaetomium has
a worldwide distribution and resides in a wide range of substrates including
cellulose-rich materials, dung, soil, and indoor environments. Numerous species
gained attention because of their ability to produce an arsenal of enzymes and
metabolites that have antimicrobial, anticancer, antioxidant, or
anti-inflammatory activities. On the other hand, some species were reported to
cause human disorders including allergic, superficial, subcutaneous, and even deep-seated
infections. Out of the 270, only eight chaetomium-like species are included in
the Atlas. Others can safely be used in industry and agriculture.
The relationship of Chaetomium is
wider, with a family Chaetomiaceae that was introduced in 1885. It first
accommodated genera that were phenotypically similar to ascosporulating Chaetomium,
but now many fungi are added on a molecular basis, irrespective of morphology
and presence of spores or conidia. As a result, the number of genera in this
family has increased to 30 (see Table). DNA data showed that also the strictly
hyphal genus Madurella, agent of human eumycetoma, is a close relative. From
2016 and onwards, Chaetomium and it is allies were dissected along
phylogenetic lines by Wang et al. (2016a,b, 2019a,b, 2022). The authors first
revised the C. globosum complex using multigene phylogeny of five
markers and concluded that not only morphology, but also ribosomal markers of ITS
and LSU were insufficient to delimit taxa in Chaetomiaceae. With this increased
level of precision, a similar approach was followed with extensive studies of
indoor and thermophilic species, and with large genera that were classically
described without ascospores, such as Humicola. This led to the acceptance
of 50 genera with 275 species by Wang et al. (2022). Thus, the number of genera
in Chaetomiaceae had almost doubled, although the number of species remained
the same. For many species, novel genera were described and a lot of names were
changed. The number of species in the genus Chaetomium sensu stricto was reduced from 270 to 44.
An implication of the above taxonomic
changes is that almost all clinical Chaetomium species changed their
names now, except for C. globosum (see
Table below). Thielavia terrestris, reported from a cerebral infection,
was changed to Thermothielavioides terrestris and Thielavia
subthermophila moved to the genus Canariomyces. This was done
because the type species of the genus Thielavia, T. basicola, appeared
to be a member of the order Melanosporales.
The Chaetomiaceae is not the only
group which appears nomenclaturally unstable. In the blog “Why fungal names are
changing?” we elucidated the reasons for changing names by taxonomists. One of
these reasons is that sequence data demonstrate that superficially similar fungi
may be phylogenetically unrelated and thus cannot be maintained in a single
genus. We gave examples in the blog “What are Coelomycetes?”, where we showed
that in the genus Phoma only five or six species are currently maintained,
instead of stunning number of 3292 names mentioned in Index Fungorum. Thus,
fungi with classical phoma-like morphology can no longer be identified as Phoma, and routine identification requires sequencing.
Phylogenetic studies are likely to be
affected by sampling: more species included, then rarely the structure of the resulting
tree remains the same. For our Atlas policy we prefer to be conservative
with changing names in groups where nomenclature is still unstable. Therefore,
several of the new chaetomium-like genera are not applied in the Atlas,
where the species are still listed under Chaetomium. In all cases, we mention
both original and new name, as well as all synonyms used in the medical
literature, as a convenience for users. We therefore advise to use “advance
search” button in the online Atlas in case a particular name can’t be
found with “chapter search”. Furthermore, care should be taken when ITS or LSU
is used for identification of Chaetomium or relatives. The β-tubulin (TUB2)
and RNA polymerase II (RPB2) genes are currently judged to be superior
in delimiting species as well as for routine identification.
Generic names in
2015 |
Generic
names in 2021 |
Achaetomiella |
Achaetomiella |
Achaetomium |
Achaetomium |
|
Acrophialophora |
|
Allobotryotrichum
|
|
Allocanariomyces |
|
Amesia |
Aporothielavia |
Aporothielavia |
|
Arcopilus |
|
Arxotrichum |
|
Batnamyces |
Bolacotricha |
- |
Bommerella |
Bommerella |
|
Botryoderma |
Botryotrichum |
Botryotrichum |
|
Brachychaeta |
|
Canariomyces |
|
Carteria |
Chaetomidium |
- |
Chaetomiopsis |
- |
Chaetomiotricha |
- |
Chaetomium |
Chaetomium |
|
Chrysanthotrichum |
|
Chrysocorona |
Cladochaete |
- |
|
Collariella |
|
Condenascus |
Corynascella |
Corynascella |
Corynascus |
Corynascus |
Crassicarpon(introduced
in 2015) |
- |
|
Dichotomopilus |
Emilmuelleria |
- |
Erythrocarpon |
- |
Erythrocarpum |
- |
Farrowia |
- |
|
Floropilus |
Humicola |
Humicola |
|
Hyalosphaerella |
|
Madurella |
|
Melanocarpus |
Melanogone |
- |
|
Microthielavia |
Myceliophthora |
Myceliophthora |
|
Mycothermus |
|
Ovatospora |
|
Parachaetomium |
|
Parathielavia |
|
Parvomelanocarpus |
Pseudocanariomyces(introduced
in 2021) |
- |
|
Pseudohumicola |
|
Pseudothielavia |
|
Remersonia |
Setiferotheca |
- |
|
Staphylotrichum |
Stellatospora |
Stellatospora |
|
Stolonocarpus |
Subramaniula |
Subramaniula |
Taifanglania |
- |
|
Tengochaeta |
|
Thermocarpiscus |
|
Thermochaetoides |
|
The-rmothelomyces |
Thielavia |
- |
|
Thermothielavioides |
Trichocladium |
Trichocladium |
Vanhallia |
- |
|
Xanthiomyces |
Names in Atlas |
Names according to Wang et al. |
Chaetomium atrobrunneum |
Amesia atrobrunnea |
Chaetomium brasiliense |
Ovatospora brasiliensis |
Chaetomium funicola |
Dichotomopilus funicola |
Chaetomium globosum |
Chaetomium globosum |
Chaetomium murorum |
Botryotrichum murorum |
Chaetomium perlucidum |
Parachaetomium perlucidum |
Chaetomium strumarium |
Achaetomium strumarium |
References:
- de Hoog
GS, Adelmann D, Ahmed AO, van Belkum A (2004) Phylogeny and typification of
Madurella mycetomatis, with a comparison of other agents of eumycetoma. Mycoses
47: 121-130.
- Kedves O,
Kocsubé S, Bata T, et al. (2021) Chaetomium and chaetomium-like species from
European indoor environments include Dichotomopilus finlandicus sp. nov.
Pathogens 3;10(9): 1133.
- Wang XW, Bai FY, Bensch K, Meijer
M, et al. (2019) Phylogenetic re-evaluation of Thielavia with
the introduction of a new family Podosporaceae. Stud. Mycol. 93: 155-252.
- Wang XW, Han PJ, Bai FY, et al. (2022) Taxonomy, phylogeny and identification of Chaetomiaceae with
emphasis on thermophilic species. Stud. Mycol. 101: 121-243.
- Wang XW, Houbraken J, Groenewald
JZ, et al. (2016) Diversity and taxonomy
of Chaetomium and chaetomium-like fungi from indoor environments.
Stud. Mycol. 84: 145-224.
- Wang XW, Lombard L, Groenewald JZ,
et al. (2016) Phylogenetic reassessment of the
Chaetomium globosum species complex. Persoonia 36: 83-133.
- Wang XW,
Yang FY, Meijer M, et al. (2019) Redefining Humicola sensu stricto and related
genera in the Chaetomiaceae. Stud. Mycol. 93: 65–153.
Best regards,
Your Atlas Team
Contact us | Online Atlas | Webshop |