Sordariomycetidae

 Chaetosphaeria inaequalis, photographed by Lucien Rommelaars.

Belongs within: Sordariomycetes.
Contains: Coniochaetales, Meliolaceae, Sordariales, Phyllachorales.

The Chaetosphaeriaceae are a group of saprobic fungi growing on decaying woody and herbaceous plant material.

Messing about with mildews
Published 9 November 2007

Black or dark mildews are parasitic fungi found on plants, particularly the leaves. There are a number of largely unrelated families of ascomycetous fungi that cause black mildew (the picture above from here shows a leaf infected by Apiosporum salicinum; I haven’t been able to establish if Apiosporium is closely related to the specific family I’m dealing with here but the general appearance is probably similar). Though parasitic on a number of food species, none of the black mildews is significant enough to have attracted a huge amount of research attention (reading between the lines, I suspect that they are also somewhat overlooked because they are more significant in the tropics than in temperate developed countries). According to Hosagoudar (2003), their growth on leaves raises the temperature in the affected area, increasing respiration and transpiration rates and reducing photosynthetic efficiency and therefore growth.

The greater part of Hosagoudar (2003) is taken up by a whirlwind tour of the taxonomic history of the Meliolaceae, one of the families of black mildews. At the time of Hosagoudar’s writing, Meliolaceae was the only family in the order Meliolales, distinguished by the unique combination of features of an ectophytic (living on the surface of leaves) mycelium with lateral appresoria (swollen points on the hyphae that press against the leaf and give rive to hyphae piercing the leaf surface) and phialides (hyphal cells producing successive spherical asexual spores in chains). At the end of the paper, almost as an afterthought, Hosagoudar establishes the family Armatellaceae for a single genus, Armatella, previously included in Meliolaceae, that lacks phialides and also differs from Meliolaceae proper in having 1-septate ascospores as opposed to 3- to 4-septate ascospores.

I have rather a problem with this sort of setup. Armatella is separated from the other Meliolaceae solely on typological grounds, without any sort of detailed analysis to establish whether the remaining Meliolaceae are truly more closely related to each other than to Armatella. The most recent Outline of Ascomycota (Eriksson 2006) accepts Armatellaceae in Meliolales, but the Notes on ascomycete systematics that first recorded Hosagoudar’s publication (Eriksson 2005) had a much more cautious reaction, noting that another genus, Diporotheca, had previously been isolated in its own family from Meliolaceae on the basis of lacking phialides. While Hosagoudar (2003) did mention Diporotheca in his taxonomic overview, no comparison of Armatella to Diporotheca was recorded. It is worth noting that in a later paper that Hosagoudar himself is an author on, Armatella has managed to quietly reinsert itself back into Meliolaceae (Biju et al. 2005)*.

*Two other possibilities must be acknowledged here, though: (A) Hosagoudar is not primary author on the latter paper, and it may be that the chosen classification represents the views of the primary author and not those of Hosagoudar, and (B) the time difference between 2003 and 2005 is small enough that Hosagoudar’s contribution to the 2005 paper may have actually occurred before he wrote the 2003 paper, with a delay in the appearance of the 2005 paper at either the collation or publication stage.

My even bigger issue, however, is to ask what exactly is the point of establishing a monogeneric family. The concept of ‘ranking’ is, in my opinion, one of the biggest issues in classification today, and I currently have something of a hate-hate relationship with ranks. It is a widely-known secret that all taxonomic ranks (with the probable, but controversial, exception of the ‘species’) are essentially arbitrary concepts, and there is no real reason why a given taxon should be recognised as an order or a family or whatever beyond how it sits in relation to other related taxa that have previously been recognised as orders or families or whatever. Different historical factors in research on different groups of organisms mean that a family of insects is in no way a comparable unit to a family of birds or plants or fungi. I personally try to avoid referring a taxon to a specific rank, at least in the privacy of my own head. The problem that really makes me grit my teeth, however, is that when it comes to trying to discuss biodiversity to other people, ranks prove so irritatingly convenient! Most people who don’t have to deal with the details of classification every day find it relatively easy to grasp the concept that each rank corresponds to a certain level of superficial distinction (at least from our own human-centric viewpoint), and that a genus represents a smaller degree of distinction than a family, which is in turn less distinct than an order. Also, try as I might, there’s only so many times I can use a variation on “clade” or “group” without becoming repetitive, confusing or both (and besides, I usually end up having to refer to “clade A” and “subclade B”, invoking an even more arbitrary sort of ranking to indicate that B is a section of A, even though there’s no actual difference between “clade” and “subclade” and, were I to change my focus slightly, I might end up referring to “clade B” and “subclade C”).

However, given that where and what an individual author chooses to recognise as a given rank is essentially subjective, what does separating a genus into its own family really tell us? The prior establishment of the genus already tells us that it is a distinctive unit. There is a certain virtue to establishing a different concept of the taxon “Meliolaceae” from the taxon “Meliolales”, rather than the previous set-up where there were two names for the exact same thing, but in establishing the taxon “Armatellaceae” to contain only “Armatella“, we again have two names for the exact same thing, and that’s just cluttering up the nomenclature.

Sordariomycetidae: soil fungi a-plenty
Published 2 September 2017

I’m pretty sure I’ve commented before that, although most of us tend to associate the word ‘fungi’ with mushrooms and other eye-catching fruiting bodies, the vast majority of fungal diversity is minute and tends to go unnoticed. Nevertheless, despite their obscurity, many of these microfungi are crucial to our own continued existence. These are the decomposers, the organisms that break down fallen plant matter and animal wastes in their own search for nourishment and so contribute to the release of locked-up nutrients back into the environmental cycle.

Neurospora growing on sugar cane waste, from here.

The group of fungi that I drew for today’s post, the Sordariomycetidae, is primarily made up of these minute decomposers. Due to a simple morphology that provides few distinct characters, the Sordariomycetidae are primarily defined on the basis of molecular phylogenies. The difficulty of classifying microfungi by morphology alone is underlined by cases where species previously classified within the same genus have proven to belong to entirely distinct fungal lineages.

In general, the vegetative body of most Sordariomycetidae consists of little more than disassociated hyphae embedded in their substrate, with the only distinct structures being the reproductive fruiting bodies. These are perithecia: that is, globular or flask-shaped fruiting bodies with a single small opening or ostiole at the top through which the mature spores are released. In some cases, the internal structure of the mature perithecium will simply dissolve, freeing the spores to escape through the ostiole in the manner of a miniature puffball. In others, the spores become entangled in a long strand or seta that is then extruded through the ostiole like toothpaste being squeezed out of a tube.

Perithecium of Chaetomium extruding spore-bearing setae, from here.

Sordariomycetids are found in almost every habitat imaginable: as well as soil- and dung-dwelling forms, they may also be found in aquatic and even marine habitats. Perhaps the best-known sordariomycetid is Neurospora crassa, red bread mould, which is widely used in laboratories as a model organism for genetic research. Indeed, it was investigations into N. crassa in the 1950s that first led to the proposal of the ‘one gene, one enzyme’ model that became a cornerstone of molecular genetics.

Systematics of Sordariomycetidae
Sordariomycetidae
| i. s.: Cryptovalsa Ces. & De Not. ex Fuckel 1870 [incl. Allescherina Berl. 1902]KC01
| Lecythium Zukal 1893 non Hertwig & Lesser 1874 (ICZN) [=Lecithium Sacc. 1895]KC01
| `--*L. aerugineum Zukal 1893RS99
| Obryzum Wallr. 1825 [Obryzaceae]KC01
|--+--ConiochaetalesHM17
| `--CephalothecaceaeHM17
| |--Cryptendoxyla Malloch & Cain 1970HM17, KC01
| | `--C. hypophloiaHM17
| `--+--Albertiniella Kirschst. 1936HM17, KC01
| | `--A. polyporicolaHM17
| `--Cephalotheca Fuckel 1871HM17, KC01 (see below for synonymy)
| |--C. foveolataHM17
| `--C. sulfureaLK04
`--+--Meliolales [Meliolomycetidae]HM17
| |--MeliolaceaeMC03
| `--Armatella Theissen & Sydow 1915H03 [incl. Artallendea Bat. & Maia 1960KC01; Armatellaceae]
| `--*A. litseae (Henn.) Theissen & Sydow 1915 [=Dimerosporium litseae]H03
`--+--SordarialesHM17
`--+--+--PhyllachoralesHM17
| `--Boliniaceae [Boliniales]HM17
| | i. s.: Apiocamarops Samuels & Rogers 1987KC01
| | Camaropella Vassiljeva 1997KC01
| | Endoxyla Fuckel 1871 (see below for synonymy)KC01
| |--Camarops Karst. 1873HM17, KC01 (see below for synonymy)
| | |--C. amorphaM-FM20
| | |--C. lutea (Albertini & Schweinitz: Fries) Nannfeldt 1972 (see below for synonymy)RS99
| | |--C. microsporaLK04
| | `--C. ustulinoidesHM17
| `--+--Cornipulvina ellipsoidesHM17
| `--Apiorhynchostoma Petr. 1923HM17, KC01
| `--A. curreyiHM17
`--ChaetosphaerialesHM17
|--HelminthosphaeriaceaeHM17
| | i. s.: Tengiomyces Réblová 1999EB03, E99 [incl. Spadicoides Hughes 1958KC01]
| | `--*T. indicus (Varghese & Rao) Réblová 1999 [=Chaetosphaerella indica]E99
| |--Echinosphaeria canescensHM17
| `--+--Ruzenia spermoidesHM17
| `--Helminthosphaeria Fuckel 1870HM17, KC01 (see below for synonymy)
| `--H. hyphodermaeHM17
`--ChaetosphaeriaceaeHM17
| i. s.: Ascochalara Réblová 1999KC01
| Ascocodinaea Samuels, Cand. & Magni 1997 [incl. Codinaea Maire 1937]KC01
| Carpoligna Fernández & Huhndorf 1999EB03, KC01
| Lecythothecium Réblová & Winka 2001EB03, KC01
| Porosphaerellopsis Samuels & Müll. 1982 [=Porosphaeria Samuels & Müll. 1979]KC01
| Striatosphaeria Samuels & Müll. 1979KC01
| Zignoella Sacc. 1878 [incl. Aposphaeriella Died. 1912, Trichocollonema Höhn. 1902]KC01
| Codinaeopsis Morgan-Jones 1976KC01
| Dictyochaeta Speg. 1923 [incl. Menisporella Agnihothr. 1962]KC01
| Melanochaeta Müll., Harr & Sulmont 1969KC01
| Melanopsammella Höhn. 1920KC01
| Porosphaerella Müll. & Samuels 1982KC01
|--+--Exserticlava Hughes 1978HM17, KC01
| | `--E. vasiformisHM17
| `--Umbrinosphaeria Réblová 1999HM17, KC01
| `--U. caesariataHM17
`--+--Sporoschisma Berk. & Broome 1847HM17, KC01 [incl. Pithospermum Mont. ex Berk. & Broome 1856KC01]
| `--S. hemipsilaHM17
`--Chaetosphaeria Tul. & Tul. 1863HM17, KC01 (see below for synonymy)
|--C. inaequalis [=Melanopsamella inaequalis, Trichosphaerella inaequalis]RS99
|--C. innumeraHM17
|--C. ovoideaSS09
`--C. tortuosa [incl. Menispora tortuosa]SS09

Camarops Karst. 1873HM17, KC01 [incl. Bolinia (Nitschke) Sacc. 1882KC01, Peridoxylon Shear 1923KC01, Peridoxylum Clem. & Shear 1931KC01, Phaeosperma Nitschke ex Otth 1869KC01, Sarcostromella Boedijn 1959KC01, Solenoplea Starbäck 1901KC01]

Camarops lutea (Albertini & Schweinitz: Fries) Nannfeldt 1972 [=Sphaeria lutea, Chromendothia lutea (Albertini & Schweinitz) Vassiljeva 1993]RS99

Cephalotheca Fuckel 1871HM17, KC01 [=Crepinula Kuntze 1891KC01; incl. Aposphaeriopsis Died. 1913KC01, Carothecis Clem. 1931KC01, Erythrosphaera Sorokīn 1871KC01]

Chaetosphaeria Tul. & Tul. 1863HM17, KC01 [incl. Bisporomyces Beyma 1940KC01, Catenularia Grove 1886KC01, Chaetolentomita Maubl. 1915KC01, Chloridium Link 1809KC01, Ciliofusa Clem. & Shear 1931KC01, Ciliofusarium Rostr. 1892KC01, Cirrhomyces Höhn. 1903KC01, Custingophora Stolk, Hennebert & Klopotek 1968KC01, Didymopsamma Petr. 1925KC01, Eriomene (Sacc.) Clem. & Shear 1931KC01, Eriomenella Peyronel 1918KC01, Erionema Maire 1906 non Penz. 1898KC01, Gongromeriza Preuss 1851KC01, Gonatotrichum Corda 1842KC01, Gonytrichum Nees & Nees 1818KC01, Haplochalara Linder 1933KC01, Lentomita Niessl 1876KC01, Melanopsammina Höhn. 1919KC01, Menispora Pers. 1822KC01, Mesobotrys Sacc. 1880KC01, Monostachys Arnaud 1954KC01, Montemartinia Curzi 1927KC01, Piminella Arnaud 1954KC01, Psilobotrys Sacc. 1879KC01, Psiloniella Costantin 1888KC01, Sphaeromycetella Arnaud 1954KC01, Urnularia Karst. 1866 (nom. rej.)KC01]

Endoxyla Fuckel 1871 [incl. Cerastomis Clem. 1931, Eutypopsis Karst. 1878, Lentomitella Höhn. 1906, Linostomella Petr. 1925]KC01

Helminthosphaeria Fuckel 1870HM17, KC01 [incl. Diplococcium Grove 1885KC01, Litschaueria Petr. 1923KC01, Luxuriomyces Castañeda 1988KC01, Tretendophragmia Subram. 1995KC01]

*Type species of generic name indicated

References

Biju, C. K., V. B. Hosagoudar & T. K. Abraham. 2005. Meliolaceae of Kerala, India—XV. Nova Hedwigia 80 (3–4): 465–502.

[E99] Eriksson, O. E. (ed.) 1999. Notes on ascomycete systematics. Nos 2440-2755. Myconet 2: 1–41.

Eriksson, O. E. (ed.) 2005. Notes on ascomycete systematics. Nos 3912–4298. Myconet 11: 115–170.

Eriksson, O. E. (ed.) 2006. Outline of Ascomycota—2006. Myconet 12: 1–82.

[EB03] Eriksson, O. E., H. O. Barah, R. S. Currah, K. Hansen, C. P. Kurtzman, G. Rambold & T. Laessøe (eds.) 2003. Outline of Ascomycota—2003. Myconet 9: 1–89.

[HM17] Hongsanan, S., S. S. N. Maharachchikumbura, K. D. Hyde, M. C. Samarakoon, R. Jeewon, Q. Zhao, A. M. Al-Sadi & A. H. Bahkali. 2017. An updated phylogeny of Sordariomycetes based on phylogenetic and molecular clock evidence. Fungal Diversity 84: 25–41.

[H03] Hosagoudar, V. B. 2003. Armatellaceae, a new family segregated from the Meliolaceae. Sydowia 55 (2): 162–167.

[KC01] Kirk, P. M., P. F. Cannon, J. C. David & J. A. Stalpers. 2001. Ainsworth & Bisby’s Dictionary of the Fungi 9th ed. CAB International: Wallingford (UK).

[LK04] Lutzoni, F., F. Kauff, C. J. Cox, D. McLaughlin, G. Celio, B. Dentinger, M. Padamsee, D. Hibbett, T. Y. James, E. Baloch, M. Grube, V. Reeb, V. Hofstetter, C. Schoch, A. E. Arnold, J. Miadlikowska, J. Spatafora, D. Johnson, S. Hambleton, M. Crockett, R. Shoemaker, G.-H. Sung, R. Lücking, T. Lumbsch, K. O’Donnell, M. Binder, P. Diederich, D. Ertz, C. Gueidan, K. Hansen, R. C. Harris, K. Hosaka, Y.-W. Lim, B. Matheny, H. Nishida, D. Pfister, J. Rogers, A. Rossman, I. Schmitt, H. Sipman, J. Stone, J. Sugiyama, R. Yahr & R. Vilgalys. 2004. Assembling the fungal tree of life: progress, classification, and evolution of subcellular traits. American Journal of Botany 91 (10): 1446–1480.

[M-FM20] Marin-Felix, Y., A. N. Miller, J. F. Cano-Lira, J. Guarro, D. García, M. Stadler, S. M. Huhndorf & A. M. Stchigel. 2020. Re-evaluation of the order Sordariales: delimitation of Lasiosphaeriaceae s. str., and introduction of the new families Diplogelasinosporaceae, Naviculisporaceae, and Schizotheciaceae. Microorganisms 8: 1430.

[MC03] Mostert, L., P. W. Crous, J. Z. Groenewald, W. Gams & R. C. Summerbell. 2003. Togninia (Calosphaeriales) is confirmed as teleomorph of Phaeoacremonium by means of morphology, sexual compatibility and DNA phylogeny. Mycologia 95 (4): 646–659.

[RS99] Rossman, A. Y., G. J. Samuels, C. T. Rogerson & R. Lowen. 1999. Genera of Bionectriaceae, Hypocreaceae and Nectriaceae (Hypocreales, Ascomycetes). Studies in Mycology 42: 1–248.

[SS09] Schoch, C. L., G.-H. Sung, F. López-Giráldez, J. P. Townsend, J. Miadlikowska, V. Hofstetter, B. Robbertse, P. B. Matheny, F. Kauff, Z. Wang, C. Gueidan, R. M. Andrie, K. Trippe, L. M. Ciufetti, A. Wynns, E. Fraker, B. P. Hodkinson, G. Bonito, J. Z. Groenewald, M. Arzanlou, G. S. de Hoog, P. W. Crous, D. Hewitt, D. H. Pfister, K. Peterson, M. Gryzenhout, M. J. Wingfield, A. Aptroot, S.-O. Suh, M. Blackwell, D. M. Hillis, G. W. Griffith, L. A. Castlebury, A. Y. Rossman, H. T. Lumbsch, R. Lücking, B. Büdel, A. Rauhut, P. Diederich, D. Ertz, D. M. Geiser, K. Hosaka, P. Inderbitzin, J. Kohlmeyer, B. Volkmann-Kohlmeyer, L. Mostert, K. O’Donnell, H. Sipman, J. D. Rogers, R. A. Shoemaker, J. Sugiyama, R. C. Summerbell, W. Untereiner, P. R. Johnston, S. Stenroos, A. Zuccaro, P. S. Dyer, P. D. Crittenden, M. S. Cole, K. Hansen, J. M. Trappe, R. Yahr, F. Lutzoni & J. W. Spatafora. 2009. The Ascomycota tree of life: a phylum-wide phylogeny clarifies the origin and evolution of fundamental reproductive and ecological traits. Systematic Biology 58 (2): 224–239.

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