Walter Gams

Trichoderma species associated with the green mold epidemic of commercially grown Agaricus bisporus

Trichoderma aggressivum sp. nov. and T. aggressivum f. europaeum f. nov. are described. These forms cause the green mold epidemic in commercially grown Agaricus bisporus in North America and Europe, respectively. In the literature they have been reported as T. harzianum biotypes Th 4 and Th 2, respectively. They are strongly separated from their closest relative, T. harzianum, in sequences of the ITS-1 region of nuclear rDNA and an approximately 689 bp fragment of the protein coding translation elongation factor gene (EF-1α). They are distinguished from the morphologically similar T. harzianum and T. atroviride (the latter also known as biotype Th 3) most readily by rate of growth. Of these, only T. harzianum grows well and sporulates at 35 C, while T. atroviride is the slowest growing. Trichoderma aggressivum f. aggressivum and f. europaeum are effectively indistinguishable morphologically although they have subtly different growth rates at 25 C on SNA and statistically significant micromorphological differences. Based on findings of this study, descriptions of T. harzianum and T. atroviride are expanded. A key to Trichoderma species commonly found associated with commercially grown A. bisporus is provided.

Infrageneric Taxa of Aspergillus

The species of Aspergillus fall into distinct clusters, which have been widely accepted. Since Thom and Church (1926), Thom and Raper (1945) and Raper and Fennell (1965), these clusters have been called “groups”, a category without nomenclatural standing. In a few cases “series” were named, which do have a nomenclatural status (when described before 1935 even without a Latin diagnosis), but they do not compete for priority unless at the same rank. For the sake of simplicity in citation, we prefer to introduce new sections rather than new combinations from previous series. In contrast, in Penicillium subgenera and sections were named at the beginning of the century and a complete scheme was formally devised by Pitt (1979).

Phylogenetic and morphotaxonomic revision of Ramichloridium and allied genera

The phylogeny of the genera Periconiella, Ramichloridium, Rhinocladiella and Veronaea was explored by means of partial sequences of the 28S (LSU) rRNA gene and the ITS region (ITS1, 5.8S rDNA and ITS2). Based on the LSU sequence data, ramichloridium-like species segregate into eight distinct clusters. These include the Capnodiales (Mycosphaerellaceae and Teratosphaeriaceae), the Chaetothyriales (Herpotrichiellaceae), the Pleosporales, and five ascomycete clades with uncertain affinities. The type species of Ramichloridium, R. apiculatum, together with R. musae, R. biverticillatum, R. cerophilum, R. verrucosum, R. pini, and three new species isolated from Strelitzia, Musa and forest soil, respectively, reside in the Capnodiales clade. The human-pathogenic species R. mackenziei and R. basitonum, together with R. fasciculatum and R. anceps, cluster with Rhinocladiella (type species: Rh. atrovirens, Herpotrichiellaceae, Chaetothyriales), and are allocated to this genus. Veronaea botryosa, the type species of the genus Veronaea, also resides in the Chaetothyriales clade, whereas Veronaea simplex clusters as a sister taxon to the Venturiaceae (Pleosporales), and is placed in a new genus, Veronaeopsis. Ramichloridium obovoideum clusters with Carpoligna pleurothecii (anamorph: Pleurothecium sp., Chaetosphaeriales), and a new combination is proposed in Pleurothecium. Other ramichloridium-like clades include R. subulatum and R. epichloës (incertae sedis, Sordariomycetes), for which a new genus, Radulidium is erected. Ramichloridium schulzeri and its varieties are placed in a new genus, Myrmecridium (incertae sedis, Sordariomycetes). The genus Pseudovirgaria (incertae sedis) is introduced to accommodate ramichloridium-like isolates occurring on various species of rust fungi. A veronaea-like isolate from Bertia moriformis with phylogenetic affinity to the Annulatascaceae (Sordariomycetidae) is placed in a new genus, Rhodoveronaea. Besides Ramichloridium, Periconiella is also polyphyletic. Thysanorea is introduced to accommodate Periconiella papuana (Herpotrichiellaceae), which is unrelated to the type species, P. velutina (Mycosphaerellaceae).

Eyespot of cereals revisited: ITS phylogeny reveals new species relationships

Four species so far classified in Pseudocercosporella or Ramulispora (hyphomycetes) are associated with eyespot disease symptoms of cereals. Two of these have been linked to teleomorphs that were described in Tapesia. Sequence data derived from the Internal Transcribed Spacer region (ITS1, 5.8S and ITS2) of the rDNA operon showed, however, that the eyespot fungi associated with Tapesia are not congeneric with Ramulispora sorghi, the type of Ramulispora. The genus name Tapesia is now rejected in favour of the conserved name Mollisia, which appears to comprise heterogeneous fungi. Tapesia yallundae is not closely related to the type of Mollisia, M. cinerea, but clusters separately, being more closely allied to species with Cadophora anamorphs. A new holomorph genus, Oculimacula, is therefore proposed for teleomorphs of the eyespot fungi, while the anamorphs are accommodated in Helgardia gen. nov.

Contribution to the taxonomy and pathogenicity of fungicolous Verticillium species. I. Taxonomy

AbstractThe genusVerticillium is divided into four sections (two new) and a residual group. The new sectionNigrescentia comprises the well-known plant-pathogenic and some other saprophytic species with dark resting structures. The new sectionAlbo-erecta is characterized by white (or yellowish) colonies and erect conidiophores and contains mainly fungicolous species. Seven (two new) species and two new varieties are described and keyed out. Three other species have known teleomorphs ofNectriopsis (one new and two new combinations). This genus had been merged withNectria by Samuels, but its retention is justified, as the original and the here described fungicolous (and myxomyceticolous) species are more suitably accomodated inNectriopsis than inHypomyces.The common causal agent of dry bubble inAgaricus bisporus, Verticillium fungicola var.fungicola, is redescribed and defined more narrowly than by Gams (1971) by its maximum growth temperature below 27°C. A similar fungus with a maximum growth temperature near 33°C, causing brown spots inA. bitorquis, is described asV. fungicola var.aleophilum. Isolates from wild agarics with a strongly reduced growth at 24°C and a maximum below 27°C, a yellowish mycelium and inconspicuous sclerotia, are described asV. fungicola var.flavidum. V. biguttatum W. Gams,sp. nov., with cylindrical biguttulate conidia, is a common soil fungus and hyperparasite ofRhizoctonia solani. Gliocladium microspermum (Sacc.) W. Gams,comb. nov., the anamorph ofNectriopsis broomeana (Tul.) W. Gams,comb. nov., which is intermediate betweenGliocladium andVerticillium, is included because of its fungicolous habit.SamenvattingHet geslachtVerticillium wordt onderverdeeld in vier secties (waaronder twee nieuwe) en een restgroep. De nieuwe sectieNigrescentia bevat onder meer de bekende ziekteverwekkende soorten met donkere ruststructuren. De nieuwe sectieAlbo-erecta wordt gekarakteriseerd door witte (of geelachtige) kolonies en rechtopstaande conidioforen en bevat hoofdzakelijk op andere fungi groeiende soorten. Zeven soorten (waaronder twee nieuwe) en twee nieuwe variëteiten worden beschreven en in een sleutel verwerkt. Drie andere soorten bezitten perfecte vormen vanNectriopsis (waaronder één nieuwe en twee nieuwe combinaties). Dit geslacht werd door Samuels metNectria samengevoegd, maar kan gehandhaafd worden en lijkt beter geschikt om de hier beschreven ascomyceten onder te brengen danHypomyces. Verticillium fungicola var.fungicola, de algemene veroorzaker van droge mollen bij de champignon (Agaricus bisporus), wordt beschreven en met zijn temperatuur-maximum beneden 27°C nauwkeuriger gedefiniëerd dan in een vroegere studie (Gams, 1971). Een vergelijkbare schimmel met een temperatuurmaximum van ongeveer 33°C, die bijA. bitorquis bruine vlekken veroorzaakt, wordt beschreven alsV. fungicola var.aleophilum. Isolaten van wilde paddestoelen met een optimum duidelijk beneden 24°C en een maximum beneden 27°C, geelachtig mycelium en onopvallende sclerotiën, worden beschreven alsV. fungicola var.flavidum. V. biguttatum W. Gams, sp. nov., met cilindrische, biguttate conidiën, is een algemene grondschimmel en hyperparasiet vanRhizoctonia solani. Gliocladium microspermum (Sacc.) W. Gams, comb. nov., de imperfecte vorm vanNectriopsis broomeana (Tul.) W. Gams, comb. nov., een tussenvorm tussenGliocladium enVerticillium, wordt opgenomen wegens zijn voorkomen op vruchtlichamen van de dennemoorder.

Togninia (Calosphaeriales) is confirmed as teleomorph of Phaeoacremonium by means of morphology, sexual compatibility and DNA phylogeny.

Petri disease, or black goo, is a serious disease of vines in most areas where grapevines are cultivated. The predominant associated fungus is Phaeomoniella chlamydospora (Chaetothyriales). Several species of Phaeoacremonium (Pm.) also are associated, of which Pm. aleophilum is the most common. Although no teleomorph is known for Phaeoacremonium, the genus Togninia previously has been linked to phaeoacremonium-like anamorphs. To investigate the possible anamorph-teleomorph connection of Phaeoacremonium to Togninia, anamorphs of Togninia minima, T. fraxinopennsylvanica and T. novae-zealandiae morphologically were compared with Pm. aleophilum and some representative cultures were mated in all combinations. Although no interspecies mating proved fertile, matings between isolates of Pm. aleophilum produced a Togninia teleomorph within 3-4 weeks. Certain field isolates of Pm. aleophilum commonly produced the teleomorph, demonstrating that both mating types can occur in the same vine and thus also explaining the genetic diversity observed for this fungus in some vineyards. To elucidate the phylogenetic relationships among these taxa, isolates were subjected to sequence analysis of the nuclear ribosomal internal transcribed spacers (ITS1, ITS2) and the 5.8S rRNA gene, as well as portions of the translation elongation factor 1 alpha (EF-1α) gene. The generic placement of teleomorphs within Togninia (Calosphaeriales) further was confirmed via phylogenetic analyses of 18S small subunit (SSU) DNA. From these sequences, morphological and mating data, we conclude that T. minima is the teleomorph of Pm. aleophilum, and that it has a biallelic heterothallic mating system. An epitype and mating type tester strains also are designated for T. minima.

Plectosporium, a new genus for Fusarium tabacinum, the anamorph of Plectosphaerella cucumerina

AbstractPlectosporium is described as a new genus for Fusarium tabacinum (≡ Cephalosporium tabacinum), the anamorph of Plectosphaerella cucumerina. The genus is characterized by moist colonies, sim...

ITS and β-tubulin phylogeny of Phaeoacremonium and Phaeomoniella species

Based on ITS and β-tubulin sequence data of 33 isolates, the newly introduced genus, Phaeomoniella was confirmed as being distinct from Phaeoacremonium (Pm.). Phylogeny inferred from DNA sequences and cultural characteristics also confirmed the species status of Pm. aleophilum and Pm. angustius , which were recently reduced to synonymy. Pm. aleophilum has an optimum growth rate at 30 °C and the ability to grow at 35°, whereas Pm. angustius has an optimum growth rate at 25 °C and does not grow at 35°. Furthermore, ITS and β-tubulin sequence data showed Pm. viticola to be indistinguishable from Pm. angustius , while a new species, Pm. mortoniae , could be distinguished from this complex.

A revision of the Verticillium fungicola species complex and its affinity with the genus Lecanicillium

Verticillium fungicola, the type species of Verticillium sect. Albo-erecta, and related taxa were studied using morphological and molecular techniques. Sequences of the ITS region and SSU rDNA suggest that V. fungicola is very close to members of the genus Lecanicillium and unrelated to other species that were originally accommodated in the same section. New combinations in Lecanicillium are proposed for Verticillium fungicola and its var. flavidum at species rank, L. f. var. aleophilum is retained as a variety. These taxa can be distinguished from each other by optimum and maximum temperatures for growth, in addition to ITS sequence differences. Morphologically, L. flavidum is also distinct by repeated branching of the conidiophores, whereas the two varieties of L. fungicola have a simple conidiophore axis.

A contribution to the knowledge of nematophagous species of Verticillium

Nine nematophagous species and two varieties ofVerticillium (Verticillium sect.Prostrata), occurring either as parasites of free-living nematodes or as parasites of cysts and eggs, are revised and keyed out.V. catenulatum is reduced to a variety ofV. chlamydosporium A similar fungus is distinguished asV. suchlasporium n. sp. (including a var.catenatum). Spicaria coccospora Drechsler is transferred toVerticillium. All species have been studied in pure culture. Ecological data are reviewed for each species.SamenvattingNegen nematofage soorten en twee variëteiten vanVerticillium (Verticillium sectieProstrata), die óf als parasieten van vrijlevende aaltjes óf als parasieten van cysten en eieren optreden, worden gereviseerd en er wordt een determinatiesleutel van gepresenteerd.V. catenulatum wordt gereduceerd tot een variëteit vanV chlamydosporium. Een hierop lijkende schimmel wordt onderscheiden als.V. suchlasporium n.sp. (incl. een variëteitcatenatum. Spicaria coccospora Drechsler wordt naarVerticillium overgebracht. Alle soorten werden in reincultuur onderzocht. Voor iedere soort worden oecologische gegevens vermeld.