Phaeoacremonium W. Gams, Crous & M.J. Wingf., Mycologia 88(5):789(1996)

For synonyms see Index Fungorum (2018)



The hyphomycetous genus Phaeoacremonium was established by Crous et al. (1996) to accommodate six species with P. parasiticum (Ajello, Georg & C.J.K. Wang) W. Gams, Crous & M.J. Wingf. as the type, which was transferred from the genus Phialophora Medlar. It is morphologically similar to Acremonium Link and Phialophora Medlar, but can be distinguished from them by its aculeate phialides and inconspicuous, non-flaring collarettes and pigmented vegetative hyphae (Crous et al. 1996). The genus Phaeoacremonium together with Togninia Berl. were accommodated in the family Togniniaceae Réblová, L. Mostert, W. Gams & Crous and in the order Togniniales Senan., Maharachch. & K.D. Hyde (Maharachchikumbura et al. 2015). Gramaje et al. (2015) reduced Togninia to synonymy with Phaeoacremonium as 13 of 26 epithets are insufficiently known and some already have names in Phaeoacremonium. Currently, only Phaeoacremonium is retained in Togniniaceae (Wijayawardene et al. 2018).

ClassificationSordariomycetes, Diaporthomycetidae, Togniniales, Togninicaceae

Type species Phaeoacremonium parasiticum (Ajello, Georg & C.J.K. Wang) W. Gams, Crous & M.J. Wingf., Mycologia 88(5):789(1996)

Distribution – Worldwide

Disease Symptoms – Brown wood streaking/Esca

Phaeoacremonium species are known as vascular plant pathogens causing wilting and dieback of several woody plants, e.g. P. fuscum L. Mostert, Damm & Crous, P. pallidum Damm, L. Mostert & Crous and P. prunicola L. Mostert, Damm & Crous which were isolated from necrotic woody tissue (Damm et al. 2008). Yellowing, wilting, dieback, canker and internal node discolouration can be observed from the trees that are affected by the species of this genus (Cloete et al. 2011; Mohommadi et al. 2013; Úrbez-Torres et al. 2014). In a cross-section of affected wood, wedge-shaped and circular wood necrosis can be observed (Sami et al. 2014).

Some species also cause human diseases, e.g. P. parasitica Ajello, Georg & C.J.K. Wang was described from a subcutaneous infection of a human patient (Ajello et al. 1974; Baddley et al. 2006). Considering its association with human infections and disease symptoms of several woody hosts, it is represented as an ecologically important group of fungi (Crous et al. 1996).

 Hosts – Woody plants with brown wood streaking, humans with phaeophyphomycotic infections, larvae of bark beetle, arthropods and soil. Species of Phaeoacremonium are associated with more than 50 plant genera.


Morphological based identification and diversity

To date, there are 65 epithets recorded in Index Fungorum (2018). Six species of Phaeoacremonium, i.e. P. aleophilum, P. angustius, P. chlamydosporum, P. inflatipes, P.  parasiticum and P. rubrigenum, were originally identified based on morphological features (Crous et al. 1996) and a key based on morphological and cultural characters was also provided, but some species were reported to have been misidentified. For instance, Phaeoacremonium chlamydosporum W. Gams, Crous, M.J. Wingf. & Mugnai was referred to a new genus, Phaeomoniella Crous & W. Gams based on its straight, pigmented conidia, dark green-brown conidiophores with light green to hyaline conidiogenous cells, a yeast-like growth in young colonies, a Phoma-like synanamorph, and producing chlamydospore-like structures in culture (Gams and Crous 2000). Subsequently, Mostert et al. (2005) re-examined all isolates of P. inflatipes and revised their taxonomy based on morphology and sequence data. Because of numerous incorrect identifications that have been made since 1996 (Crous et al. 1996; Gams and Crous 2000), it is difficult to use the key provided by Crous et al. (1996) for identification (Mostert et al. 2005). An updated multiple-entry electronic key was developed by Mostert et al. (2005). During 2006–2018, about 36 new species were described, most of which were identified based on DNA sequence data (Gramaje et al. 2009; Gramaje et al. 2014; Ariyawansa et al. 2015b; Gramaje et al. 2015; Crous et al. 2016).

Mostert et al. (2005) suggested that a combination of macromorphological characters (including colonial colour, growth rate, maximum growth temperature and sometimes the size and extent of mycelial warts can be distinguishing features in several species as well) and micromorphological characters (including conidiophores, phialides type, to a less extent the shape of conidia) proved useful in identification. The representative features are warty mycelium, pigmented conidiophores with phialidic conidiogenous cells and hyaline, aseptate conidia which vary from oblong-ellipsoidal to allantoid in shape. Normally the conidia gather in slimy heads at phialide apices (Gramaje et al. 2015). However, minor differences in cultural and microscopic features also cause misidentification for several species (Mostert et al. 2005). Therefore, molecular data is necessary to deeply understand these species.

Molecular based identification and diversity

Presently, Phaeoacremonium has been reported to represent a monophyletic group of taxa (Gramaje et al. 2015). There have been studies done to investigate phylogenetic relationships among a large number of species. Mostert et al. (2006) provided a rapid identification method for 22 species of Phaeoacremonium with 23 species-specific primers. It facilitates the understanding of indiscernible species in a plant as well as in human disease, however, is the key still needs to be validated. Phylogenetic analysis based on individual LSU and SSU sequence data have good performance in the study of generic placement. Analyses showed that Phaeoacremonium species form a distinct clade within Sordariomycetes and have a close affinity with Diaporthales and Calosphaeriales species (Mostert et al. 2003; Damm et al. 2008; Gramaje et al. 2015; Crous et al. 2016). Herewith, we update the phylogenetic relationship of Phaeoacremonium species by analysing the concatenated alignment of TUB2 and ACT sequence data. Molecular data of three species are not included in the phylogenetic analysis; for P. aquaticum and P. leptorrhynchum only ITS is available, for P. inconspicuum no ex-type culture or DNA sequence data exist (Gramaje et al. 2015). In the phylogenetic tree, three distinct clades were observed, and the topological structure is in accordance with Silva et al (2017).

Recommended genetic markers (genus level) – SSU, LSU

Recommended genetic markers (species level) – ACT, TUB2

Multigene phylogeny gives a deeper understanding of the phylogenetic relationships of Phaeoacremonium species. For example, combined ITS- TEF1-α – regions (Mostert et al. 2003), combined ITS-TUB2-ACT-TEF1-α dataset (Úrbez-Torres et al. 2014) and combined ACT-TUB2 regions can resolve intraspecific identification; of which ACT-TUB2 sequence data analysis was frequently used for the investigation of taxonomy and diversity among Phaeoacremonium as it provides topologies with greater resolution and well supported (Damm et al. 2008, Essakhi et al. 2008, Gramaje et al. 2015, Silva et al. 2017, Spies et al. 2018).

Accepted number of species: There are 65 species epithets in Index Fungorum (2018) under this genus. However, only 62 are accepted. This is because P.aleophilum and P. mortoniae were treated as basionym of P. minimum and P. fraxinopennsylvanicum, respectively (Gramaje et al. 2015). Phaeoacremonium chlamydosporum was transferred to a new genus, Phaeomoniella (Gams and Crous 2000).

References: Crous et al. 1996 (morphology and a key for Phaeoacremonium species), Mostert et al. 2005 (morphology, phylogeny and a key for Phaeoacremonium species), Úrbez-Torres et al. 2014 (detection, morphology, phylogeny and pathogenicity), Gramaje et al. 2015, Maharachchikumbura et al. 2016 (morphology and phylogeny).


Table  Phaeoacremonium Details of the isolates used in the phylogenetic analyses. Ex-type (ex-epitype) strains are in bold and marked with an * and voucher strains are in bold.

Species Isolate TUB2 Actin
Phaeoacremonium africanum CBS 120863=STE-U 6177 * EU128100 EU128142
P. album BS 142688= STE-U 8379 = PMM1938 * KY906885 KY906884
CBS 142689 = STE-U 8378 = PMM2275 KY906925 KY906924
P. aleophilum = P. minimum CBS 246.91 * AF246811 AY735497
CBS 100397 AF246806 AY735498
P. alvesii CBS 110034 * AY579301 AY579234
CBS 729.97 AY579302 AY579235
P. amstelodamense CBS 110627 * AY579295 AY579228
P. amygdalinum CBS 128570=Psp-3 * JN191307 JN191303
Psp-1 JN191305 JN191301
P. angustius CBS 114992 * DQ173104 DQ173127
CBS 114991 DQ173103 DQ173126
P. argentinense CBS 777.83 * DQ173108 DQ173135
P. armeniacum ICMP 17421 * EU596526 EU595463
P. aureum CBS 142690 = STE-U 8374 = CSN1322 KY906799 KY906798
CBS 142691 = STE-U 8372 = CSN23 * KY906657 KY906656
P. australiense CBS 113589 * AY579296 AY579229
CBS 113592 AY579297 AY579230
P. austroafricanum CBS 112949 * DQ173099 DQ173122
CBS 114994 DQ173102 DQ173125
P. bibendum CBS 142694 = STE-U 8365 = CSN894 * KY906759 KY906758
P. canadense PARC327 * KF764651 KF764499
P. cinereum CBS 123909=Pm5 * FJ517161 FJ517153
Pm4 FJ517160 FJ517152
P. croatiense CBS 123037=113Pal * EU863482 EU863514
P. fraxinopennsylvanicum=P. mortoniae CBS 110212 DQ173109 DQ173136
P. fraxinopennsylvanica CBS101585 * KF764684 DQ173137
P. fuscum CBS 120856=STE-U 5969 * EU128098 EU128141
P. gamsii CBS 142712= STE-U 8366 = CSN670 * KY906741 KY906740
P. geminum CBS 142713= STE-U 8402 = C741 = CSN1944 * KY906649 KY906648
CBS 142717 = STE-U 8367 = C631 = CSN1945 KY906647 KY906646
P. globosum ICMP 16988 * EU596525 EU595466
ICMP 16987 EU596527 EU595459
P. griseo-olivaceum CBS 120857 =STE-U 5966 * EU128097 EU128139
P. griseorubrum CBS 111657 * AY579294 AY579227
CBS 566.97 AF246801 AY579226
P. hispanicum CBS 123910=Pm8 * FJ517164 FJ517156
P. hungaricum CBS 123036=90Pal * EU863483 EU863515
P. inflatipes CBS 391.71 * AF246805 AY579259
CBS 113273 AY579323 AY579260
P. iranianum CBS 101357 * DQ173097 DQ173120
CBS 117114 DQ173098 DQ173121
P. italicum CBS 137763=Pm19 * KJ534074 KJ534046
CBS 137764=Pm20 KJ534075 KJ534047
P. junior CBS 142695 = STE-U 8398 = CSN13 KY906651 KY906650
CBS 142697= STE-U 8397 = CSN273* KY906709 KY906708
CBS 142698 = STE-U 8396 = PMM2445 KY906943 KY906942
P. krajdenii CBS 109479 * AY579330 AY579267
CBS 110118 AY579324 AY579261
P. longicollarum CBS 142699 = STE-U 8393 = CSN84* KY906689 KY906688
CBS 142700 = STE-U 8395 = PMM1900 KY906879 KY906878
STE-U 8394 = CSN655 KY906733 KY906732
P. luteum CBS 137497=A16 * KF823800 KF835406
P. meliae CBS 142709 = STE-U 8391 = CSN256 KY906705 KY906704
CBS 142710 = STE-U 8392 = PMM975 * KY906825 KY906824
P. novae-zealandiae CBS 110156 * DQ173110 DQ173139
CBS 110157 DQ173111 DQ173140
P. occidentale ICMP 17037 * EU596524 EU595460
P. oleae CBS 142701 = STE-U 8381 = CSN403 KY906719 KY906718
CBS 142704= STE-U 8385 = PMM2440 * KY906937 KY906936
P. pallidum CBS 120862=STE-U 6104 * EU128103 EU128144
P. parasiticum CBS 860.73 * AF246803 AY579253
CBS 514.82 AY579306 AY579240
P. paululum CBS 142705 = STE-U 8389 = PMM1914 * KY906881 KY906880
Phaeoacremonium pravum CBS 142686 = STE-U 8363 = CSN3 * KY084246 KY084248
  CBS 142687 = STE-U 8364 = CSN11 KY084245 KY084247
Phaeoacremonium proliferatum CBS 142706 = STE-U 8368 = PMM2231 * KY906903 KY906902
  CBS 142707 = STE-U 8369 = PMM990 KY906827 KY906826
P. prunicola STE-U 5967, CBS 120858, Ex-type EU128095 EU128137
STE-U 5968 EU128096 EU128138
P. pseudopanacis CPC 28694=CBS 142101 * KY173609 KY173569
P. roseum PARC273* KF764658 KF764506
P. rosicola CBS 142708= STE-U 8390 = PMM1002 * KY906831 KY906830
P. rubrigenum CBS 498.94 * AF246802 AY579238
CBS 112046 AY579305 AY579239
P. santali CBS 137498 =A28 * KF823797 KF835403
P. scolyti CBS 112585, CCF 3266 AY579292 AY579223
CBS 113597, STE-U 3092* AF246800 AY579224
P. sicilianum CBS 123034=48Pal* EU863488 EU863520
CBS 123035=49Pal EU863489 EU863521
P. spadicum CBS 142711= STE-U 8386 = PMM1315* KY906839 KY906838
CBS 142714 = STE-U 8388 = CSN49 KY906667 KY906666
P. sphinctrophorum CBS 337.90* DQ173113 DQ173142
CBS 694.88 DQ173114 DQ173143
P. subulatum CBS 113584* AY579298 AY579231
CBS 113587 AY579299 AY579232
P. tardicrescens CBS 110573* AY579300 AY579233
P. tectonae MFLUCC 13-0707* KT285563 KT285555
P. theobromatis CBS 111586* DQ173106 DQ173132
P. tuscanicum CBS 123033=1Pal* EU863458 EU863490
P. venezuelense CBS 651.85* AY579320 AY579256
CBS 113595 AY579319 AY579255
P. vibratile CBS 117115 DQ649063 DQ649064
P. viticola CBS 101738=LCP 93 3886* AF192391 DQ173131
CBS 113065 DQ173105 DQ173128
Pleurostomophora richardsiae CBS 270.33* AY579334 AY579271 
Wuestineaia molokaiensis CBS 114877=STE-U3797* AY579335 AY579272


Fig.  Phylogenetic tree generated by maximum likelihood analysis of combined TUB2 and ACT sequence data of Phaeoacremonium species. Sequences were obtained from GenBank. Ninety-seven strains are included in the analyses, which comprise 815 characters including gaps. Single gene analyses were carried out to compare the topology of the tree and clade stability. The tree was rooted with Wuestneia molokaiensis (CBS 114877) and Pleurostomophora richardsiae (CBS 270.33). Tree topology of the Bayesian analysis was similar to the RAxML. The best scoring RAxML tree with a final likelihood value of -14544.681166 is presented. The matrix had 591 distinct alignment patterns, with 4.52% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.225480, C = 0.307476, G = 0.225692, T = 0.241352; substitution rates AC = 1.148614, AG = 4.470582, AT = 1.079312, CG = 0.984112, CT = 4.144633, GT = 1.000000; gamma distribution shape parameter α = 1.818569. RAxML support values greater than 50% (left), Bayesian posterior probabilities greater than 0.90 (middle) and MP bootstrap value higher than 50% (right) are indicated near the nodes.. The scale bar indicates 0.08 changes. The ex-type strains are in bold.

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