Highlights of the Didymellaceae - Studies in Mycology
Highlights of the Didymellaceae - Studies in Mycology
Highlights of the Didymellaceae - Studies in Mycology
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
AveSkAMp et al.<br />
Treatment <strong>of</strong> <strong>the</strong> clades<br />
Clade 1, Outgroup:<br />
Pseudorobillarda phragmitis was selected as outgroup on <strong>the</strong><br />
basis <strong>of</strong> <strong>the</strong> studies conducted by De Gruyter et al. (2009). This<br />
species, although be<strong>in</strong>g recognised as a coelomycete, is not only<br />
phylogenetically, but also morphologically dist<strong>in</strong>ct from Phoma,<br />
although Sutton (1980) classified it <strong>in</strong> <strong>the</strong> Phialopycnidi<strong>in</strong>eae.<br />
Clade 2, Sporormiaceae:<br />
In <strong>the</strong> basal l<strong>in</strong>eages, Sporormiella m<strong>in</strong>ima (CBS 524.50) was<br />
recovered, represent<strong>in</strong>g <strong>the</strong> Sporormiaceae, which was recently<br />
recircumscribed (Barr 2000). In <strong>the</strong> same clade, two species<br />
were recovered that are described <strong>in</strong> Phoma section Phoma: Ph.<br />
capitulum and Ph. m<strong>in</strong>utispora. Both species are dist<strong>in</strong>guishable<br />
from o<strong>the</strong>r species <strong>in</strong> this Boeremaean section by <strong>the</strong> production <strong>of</strong><br />
relatively small subglobose conidia (measur<strong>in</strong>g ca. 2–5 × 1.5–3 μm)<br />
with a few, large guttules. With<strong>in</strong> <strong>the</strong> Sporormiaceae, teleomorphs<br />
species have been reported with phoma-like anamorphs, such<br />
as Westerdykella dispersa (Von Arx 1981). Two Sporormiaceaeassociated<br />
genera, Sporormia and Preussia, have been mentioned<br />
as possible teleomorph for Ph. deserticola (Von Arx & Storm<br />
1967), a species that was regarded as miscellaneous by Boerema<br />
et al. (2004). Also <strong>the</strong>se anamorphs produce m<strong>in</strong>ute (sub-)<br />
globose conidia (Von Arx 1981, Boerema et al. 2004). Although<br />
<strong>the</strong> Sporormiaceae belongs to <strong>the</strong> Pleosporales (Barr 2000,<br />
2002, Shearer et al. 2009, Suetrong et al. 2009), it forms a ra<strong>the</strong>r<br />
basal clade to most <strong>of</strong> <strong>the</strong> o<strong>the</strong>r Phoma species, and a taxonomic<br />
revision <strong>of</strong> Ph. capitulum and Ph. m<strong>in</strong>utispora should <strong>the</strong>refore be<br />
considered.<br />
Clade 3, Melanommataceae:<br />
One species that belongs to <strong>the</strong> Melanommataceae was <strong>in</strong>cluded<br />
<strong>in</strong> <strong>the</strong> phylogenetical reconstruction <strong>of</strong> <strong>the</strong> phomoid Pleosporales.<br />
This species, Aposphaeria popul<strong>in</strong>a (CBS 543.70), is recovered<br />
<strong>in</strong> <strong>the</strong> basal l<strong>in</strong>eages <strong>of</strong> <strong>the</strong> reconstructed tree (Mugambi &<br />
Huhndorf 2009, Suetrong et al. 2009, Tanaka et al. 2009). The<br />
close association <strong>of</strong> this family with <strong>the</strong> Sporormiaceae and <strong>the</strong>ir<br />
phylogenetic placement <strong>in</strong> <strong>the</strong> basal l<strong>in</strong>eages <strong>of</strong> <strong>the</strong> Pleosporales<br />
is <strong>in</strong> congruence with results obta<strong>in</strong>ed <strong>in</strong> earlier studies (Kruys et<br />
al. 2006, De Gruyter et al. 2009). Although some earlier workers<br />
regularly mistook several Phoma species for members <strong>of</strong> <strong>the</strong> genus<br />
Aposphaeria (e.g. Saccardo 1884), none <strong>of</strong> <strong>the</strong> Phoma species<br />
<strong>in</strong>cluded <strong>in</strong> this study were cluster<strong>in</strong>g with <strong>the</strong> Melanommataceae.<br />
Clade 4:<br />
This clade comprises a range <strong>of</strong> species that almost all belong to<br />
different genera. Phoma l<strong>in</strong>i and Ph. flavescens are <strong>the</strong> two Phoma<br />
representatives found <strong>in</strong> this clade, although <strong>the</strong>y are not sister species.<br />
Based on morphological data, both species were accommodated <strong>in</strong><br />
Phoma section Phoma (De Gruyter et al. 1993). Both species produce<br />
a yellow diffusible pigment <strong>in</strong> vitro, although a positive reaction to NaOH<br />
is only observed <strong>in</strong> Ph. l<strong>in</strong>i. Both Ph. flavescens and Ph. l<strong>in</strong>i are closely<br />
related to Paraconiothyrium m<strong>in</strong>itans (≡ Coniothyrium m<strong>in</strong>itans; Verkley<br />
et al. 2004). With this formal recomb<strong>in</strong>ation <strong>in</strong>to Paraconiothyrium, it<br />
was aimed to differentiate Par. m<strong>in</strong>itans, which produces complex,<br />
thick-walled pycnidia from o<strong>the</strong>r Coniothyrium species that normally<br />
produce more phomoid pycnidia (Verkley et al. 2004). The close<br />
relationship between Par. m<strong>in</strong>itans with C. fuckelii that is found here is<br />
<strong>in</strong> congruence with <strong>the</strong> observations <strong>of</strong> Damm et al. (2008), although<br />
<strong>the</strong> teleomorph name, Leptosphaeria coniothyrium, would suggest a<br />
association with <strong>the</strong> Leptosphaeriaceae (clade 8).<br />
16<br />
The likel<strong>in</strong>ess <strong>of</strong> <strong>the</strong> f<strong>in</strong>d<strong>in</strong>gs <strong>of</strong> Pyrenochaeta romeroi (CBS<br />
252.60), Asteromella tiliae (CBS 265.94) and Neottiospor<strong>in</strong>a<br />
paspali (CBS 331.37) <strong>in</strong> this clade was already discussed by De<br />
Gruyter et al. (2009).<br />
Clade 5, Cucurbitariaceae:<br />
Clade 5 comprises ma<strong>in</strong>ly taxa with setose pycnidia, <strong>in</strong>clud<strong>in</strong>g<br />
several representative species <strong>of</strong> <strong>the</strong> genus Pyrenochaeta. In<br />
addition, a Coniothyrium sp., Phialophorophoma litoralis and<br />
Pleurophoma cava grouped <strong>in</strong> this clade, as well as two Phoma<br />
species, Ph. pratorum (section Phoma) and Ph. terricola, (section<br />
Paraphoma). Ano<strong>the</strong>r representative <strong>of</strong> <strong>the</strong> section Paraphoma that<br />
is <strong>in</strong>cluded <strong>in</strong> this study is Ph. radic<strong>in</strong>a, which is however found<br />
<strong>in</strong> clade 6. The taxonomy <strong>of</strong> setose species that are currently<br />
classified <strong>in</strong> Phoma section Paraphoma, Pyrenochaeta and<br />
Pleurophoma is revised (De Gruyter et al. 2010). Also <strong>in</strong> several<br />
non-Paraphoma species <strong>in</strong> <strong>the</strong> genus Phoma setose or semi-pilose<br />
pycnidia do occur <strong>in</strong>cidentally (Boerema et al. 2004). However, thus<br />
far, no setae-form<strong>in</strong>g Ph. pratorum stra<strong>in</strong>s have been recorded. The<br />
f<strong>in</strong>d<strong>in</strong>g <strong>of</strong> this species <strong>in</strong> <strong>the</strong> present clade is thus highly remarkable.<br />
The Coniothyrium stra<strong>in</strong> <strong>in</strong> this clade (CBS 122787) was<br />
previously identified as C. cerealis, and is found to be closely<br />
related to Pyrenochaeta acicola (BPP = 0.99, RBS = 100 %).<br />
As was illustrated <strong>in</strong> a previous study <strong>of</strong> Muthumeenakshi et al.<br />
(2001) C. cerealis is quite distantly related to o<strong>the</strong>r Coniothyrium<br />
species. However, based on comparison with sequence data<br />
available <strong>in</strong> GenBank, it is unlikely that its previous identification<br />
was correct. This f<strong>in</strong>d<strong>in</strong>g fur<strong>the</strong>r illustrates <strong>the</strong> polyphyly <strong>of</strong> <strong>the</strong><br />
genus Coniothyrium, which fur<strong>the</strong>r has been retrieved <strong>in</strong> clades 4, 6<br />
(Phaeosphaeriaceae), 7 (Leptosphaeriaceae and Pleosporaceae)<br />
and 8 (<strong>Didymellaceae</strong>). As mentioned before, some species <strong>of</strong><br />
this genus have been associated with <strong>the</strong> teleomorph genus<br />
Leptosphaeria, and are thus expected to cluster with <strong>the</strong><br />
Leptosphaeriaceae (clade 7). None <strong>of</strong> <strong>the</strong> species recovered <strong>in</strong><br />
clade 5 has been associated with a teleomorph.<br />
Clade 6, Phaeosphaeriaceae:<br />
The species that are found <strong>in</strong> <strong>the</strong> well-supported clade 6 (BPP =<br />
1.00; RBS = 83 %), belong to <strong>the</strong> morphologically heterogeneous<br />
group <strong>of</strong> <strong>the</strong> Phaeosphaeriaceae (Boehm et al. 2009, Zhang et al.<br />
2009). Most f<strong>in</strong>d<strong>in</strong>gs <strong>in</strong> this clade have already been discussed <strong>in</strong> <strong>the</strong><br />
previous paper <strong>of</strong> De Gruyter et al. (2009). In addition to that study,<br />
six Phoma species are retrieved <strong>in</strong> this clade. Phoma radic<strong>in</strong>a, type<br />
<strong>of</strong> Phoma section Paraphoma, is found <strong>in</strong> close association with<br />
Ph. chrysan<strong>the</strong>micola (BPP = 1.00; RBS = 90 %). The association<br />
between Ph. radic<strong>in</strong>a and <strong>the</strong> Phaeosphaeriaceae is fur<strong>the</strong>r<br />
discussed by De Gruyter et al. (2010). Its close association with<br />
Ph. chrysan<strong>the</strong>micola has been observed before by Aveskamp et<br />
al. (2008a), but <strong>the</strong> l<strong>in</strong>k with <strong>the</strong> Phaeosphaeriaceae has not been<br />
established. Stra<strong>in</strong>s <strong>of</strong> Ph. chrysan<strong>the</strong>micola exhibit some semisetose<br />
pycnidia that are, however, <strong>of</strong>ten fully covered by mycelial<br />
hairs (Boerema 1993). This is a feature that is <strong>in</strong> common with Ph.<br />
radic<strong>in</strong>a, which has, as type species <strong>of</strong> <strong>the</strong> section Paraphoma,<br />
clearly visible setae. In contrast, <strong>the</strong> ma<strong>in</strong> characteristic <strong>of</strong> Ph.<br />
chrysan<strong>the</strong>micola, <strong>the</strong> presence <strong>of</strong> pseudosclerotioid masses, has<br />
never been observed <strong>in</strong> <strong>the</strong> latter species. However, also not all<br />
stra<strong>in</strong>s <strong>of</strong> Ph. chrysan<strong>the</strong>micola exhibit this character (Dorenbosch<br />
1970).<br />
Phoma fimeti forms a subclade with Ph. samarorum and a<br />
stra<strong>in</strong> that was previously identified as Stenocarpella macrospora<br />
(BPP = 0.98; RBS = 67 %), but that is probably misidentified (De