DNA extraction, amplification and sequencing

Total genomic DNA was extracted from fresh colonies using the Wizard® Genomic DNA Purification Kit (Promega Corporation, Madison, WI, USA), following the manufacturer's protocol. The internal transcribed spacer (ITS) regions and the 5′ end of the 28S nrRNA gene (LSU) were amplified and sequenced with the primer pairs ITS5/ITS4 (White et al. 1990) and LR0R/LR5 (Vilgalys and Hester, 1990, Vilgalys and Sun, 1994), respectively. Fragments of the translation elongation factor 1-alpha (TEF1-α) and RNA polymerase II second largest subunit (RPB2) genes were amplified with the primer sets EF1-983F/EF1-2218R (Rehner & Buckley 2005) and RPB2-5F2/RPB2-7cR (Liu et al. 1999), correspondingly. In addition, fragments of actin (ACT), elongation factor (EF) and tryptophan synthase (TS) were amplified for Verticillium species with the following primer sets: VActf/VActR for ACT, VEFf/VEFr for EF and VTs3f/ VTs3r for TS (Inderbitzin et al. 2011b). Polymerase chain reaction (PCR) protocols followed Zuccaro et al., 2004, Inderbitzin et al., 2011b and Grum-Grzhimaylo et al. (2013). The program SeqMan v. 12.1.0 (DNASTAR, Madison, WI, USA) was used to obtain consensus sequences of each isolate.

Phylogenetic analysis

Sequences of each locus were aligned through MAFFT v. 7 (Katoh et al. 2017), using the default parameters, and were manually corrected in MEGA v. 6.06 (Tamura et al. 2013). Phylogenetic reconstructions were based on Maximum Composite Likelihood (ML) and were performed on the CIPRES Science Gateway portal (Miller et al. 2012) using RAxML v. 8.2.9. The selection of the best-fit nucleotide substitution model for each locus was calculated with MrModelTest v. 2.3 (Nylander 2004). For ML analyses, the default parameters were used, and bootstrap support (BS) was carried out using the rapid bootstrapping algorithm with the automatic halt option. A BS value ≥70 % was considered as statistically significant. Each partition was assessed for incongruence before being concatenated by checking individual phylogenies for conflicts between clades with significant ML support (Mason-Gamer and Kellogg, 1996, Wiens, 1998). All novel DNA sequences generated in this study were deposited in GenBank and the European Nucleotide Archive (ENA) (Table 1), while the alignments and the resulting trees were accessioned in TreeBASE (http://www.treebase.org) and the taxonomic novelties in MycoBank (http://www.MycoBank.org, Crous et al. 2004).

Clade I

Gibellulopsis Bat. & H. Maia, Anais Soc. Biol. Pernambuco 16: 153. 1959.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae. Conidiophores arising from submerged or superficial hyphae, more or less erect, mostly terminal, usually 1–2 times branched, bearing one or two verticillate branches at a node. Conidiogenous cells enteroblastic, monophialidic, terminal, lateral, subulate or cylindrical, hyaline, with inconspicuous collarette and distinct periclinal thickening at the conidiogenous locus. Conidia elongate ellipsoidal to cylindrical, 1- or 2-celled, hyaline, smooth-walled, produced in slimy heads. Chlamydospores lateral, terminal or intercalary, singly or in chains, pale to dark brown, smooth- and thick-walled. Sexual morph unknown (modified from Zare et al. 2007).

Type species: Gibellulopsis serrae (Maffei) Giraldo & Crous (= Gibellulopsis piscis Bat. & H. Maia).

Gibellulopsis aquatica Giraldo López & Crous, sp. nov. MycoBank MB828033. Fig. 3.

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Fig. 3

Gibellulopsis aquatica (ex-type CBS 117131). A. Colony on PDA after 14 d at 25 °C. B–F. Conidiophores. G, H. Chlamydospores. I. Conidia. Scale bars: B, C = 20 μm; D–H = 10 μm; I = 5 μm.

Etymology: From the Latin aquaticus, in reference to the freshwater habitat of the fungus.

Mycelium consisting of branched, septate, smooth, hyaline and thin-walled hyphae, up to 2 μm wide. Conidiophores arising from submerged or superficial hyphae, erect, up to 4 septa at the base, simple or poorly branched, bearing 1–6 levels with 1–2 phialides per node, ca. up to 104 μm long, 1.5–2.5 μm wide at the base, hyaline, smooth-walled, with cell walls usually thicker than those of the vegetative hyphae. Phialides terminal, lateral, cylindrical, hyaline, thick- and smooth-walled, often borne on short cylindrical subtending cells; 19–48.5 μm long, 1.5–2 μm wide at the base, with inconspicuous collarette and periclinal thickening at the conidiogenous locus. Conidia cylindrical with rounded ends or ellipsoidal, sometimes with a slightly truncate base, 1-celled, hyaline, thin- and smooth-walled, 3.9–6.1 × 1.6–2.5 μm, arranged in slimy heads. Chlamydospores intercalary, in single or branched chains, subglobose to elongated, olivaceous brown, smooth- and thick-walled, 3.2–9.1 × 3.9–6.9 μm. Sexual morph not observed.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 68‒70 mm diam, flat, floccose at centre, glabrous at periphery, entire margin, dirty white, reverse uncoloured. On OA reaching 57‒59 mm diam, flat, dusty, entire margin, white, reverse uncoloured.

Specimen examined: France, from cloud water, unknown date, M. Sancelme (holotype CBS H-23649, culture ex-type CBS 117131).

Notes: The type culture of Gibellulopsis aquatica is placed in a single branch which is sister to the clade (90 % BS) harbouring G. serrae, G. catenata and G. nigrescens. Although G. aquatica produces branched chains of chlamydospores as does G. catenata, the production of these structures remained scarce after 14 d, becoming profuse after 21 d. Only 1-celled conidia were observed in all media tested.

Gibellulopsis catenata Giraldo López & Crous, sp. nov. MycoBank MB828035. Fig. 4.

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Fig. 4

Gibellulopsis catenata (ex-type CBS 113951). A. Colony on PDA after 14 d at 25 °C. B–D. Conidiophores. E, F. Chlamydospores. G. Conidia. Scale bars = 10 μm.

Etymology: Named after the production of chlamydospores in chains.

Mycelium consisting of branched, septate, smooth, hyaline and thin-walled hyphae, up to 2 μm wide. Conidiophores arising from submerged or superficial hyphae, (sub-)erect, simple or poorly branched, bearing 1–2 levels with 2–3 phialides per node, ca. up to 96 μm long, 1.5–2.5 μm wide at the base, hyaline, smooth-walled, with cell walls usually thicker than those of the vegetative hyphae. Phialides terminal, lateral, cylindrical or acicular, hyaline, thick- and smooth-walled, 29–61 μm long, 1.5–2 μm wide at the base, with inconspicuous collarette and periclinal thickening at the conidiogenous locus, occasionally with a percurrent proliferation. Conidia cylindrical with rounded ends, 1- or 2-celled, hyaline, thin- and smooth-walled, 4.1–12.9 × 1.5–2.8 μm, arranged in slimy heads. Chlamydospores terminal, lateral or intercalary, mostly in single or branched chains, subglobose or ellipsoidal, pale brown, smooth- and thick-walled, 5.3–9 × 3.9–6.9 μm. Sexual morph not observed.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 48 mm diam, flat, woolly, entire margin, fuscous black at centre and white at periphery, reverse fuscous black. On OA reaching 44‒45 mm diam, flat, dusty, entire margin, white, reverse uncoloured.

Specimen examined: Germany, from cervical swab of mare, unknown date and collector (holotype CBS H-23650, culture ex-type CBS 113951).

Notes: Gibellulopsis catenata is represented by a single isolate, which is placed in a single branch basal to the main clade (86 % BS) containing G. serrae, G. aquatica and G. nigrescens. Gibellulopsis catenata can be morphologically distinguished from the other species of the genus by the production of long branched chains of chlamydospores and by formation of 2-celled conidia.

Gibellulopsis fusca (Thirum. & Sukapure) Giraldo López & Crous, comb. et stat. nov. MycoBank MB828038. Fig. 5.

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Fig. 5

Gibellulopsis fusca (ex-type CBS 560.65). A. Colony on OA after 14 d at 25 °C. B–D. Conidiophores. E–G. Chlamydospores. H. Conidia. Scale bars = 10 μm.

Basionym: Cephalosporium serrae var. fuscum Thirum. & Sukapure, Mycologia 58: 360. 1966.

Synonyms: ? Cephalosporium apii M.A. Smith & Ramsey, Bot. Gaz.112: 399. 1951.

? Acremonium apii (M.A. Smith & Ramsey) W. Gams, Cephalosporium-artige Schimmelpilze 136. 1971.

Mycelium consisting of branched, septate, smooth, hyaline and thin-walled hyphae, 1.5–2.5 μm wide. Conidiophores arising from submerged or superficial hyphae, erect or slightly curved, simple or poorly branched, up to 65 μm long, 1.5–2 μm wide at the base, hyaline, smooth-walled, with cell walls usually thicker than those of the vegetative hyphae. Phialides lateral, cylindrical or subulate, hyaline, thick- and smooth-walled, occasionally borne on short cylindrical subtending cells; 32–65 μm long, 1.5–2 μm wide at the base, with inconspicuous collarette and periclinal thickening at the conidiogenous locus, occasionally with a percurrent proliferation. Conidia cylindrical with rounded ends, 1- or 2-celled, hyaline, thin- and smooth-walled, 6.9–13.7 × 2.5–4 μm, arranged in slimy heads. Chlamydospores lateral or intercalary, single or in pairs, with or without intermittent hyaline cells, subglobose, ellipsoidal or obpyriform, brown, smooth- and thick-walled, 6.5–10 × 4.7–6.7 μm. Sexual morph not observed.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 40‒42 mm diam, flat, velvety, white, reverse becoming grey to black with age. On OA reaching 57‒59 mm diam, flat, felty, white, reverse becoming grey with age. On PCA reaching 34‒38 mm diam, flat, scarce aerial mycelium, white, reverse uncoloured. On MEA reaching 51‒53 mm diam, raised, cottony, white, reverse dark brown to black.

Specimens examined: Germany, Giessen, from Apium graveolens, unknown date and collector, CBS 308.38. India, Banaras, from soil, Dec. 1962, M.J. Thirumalachar (holotype CBS H-19291, culture ex-type CBS 560.65 = ATCC 16090 = HACC 149 = IMI 112791). Iran, Mashad, from Beta vulgaris, unknown date and collector, CBS 120818. Netherlands, Baarn, from Aegopodium podagraria, unknown date, H.A. van der Aa, CBS 402.80; from Apium graveolens, unknown date and collector, CBS 747.83.

Notes: This clade contains two isolates from Apium graveolens (CBS 308.38 and CBS 747.83), one from Beta vulgaris (CBS 120818), one from Aegopodium podagraria (CBS 402.80) and one from plant debris (CBS 560.65); which form a basal clade (82 % BS) to the remaining species from the genus. Since this clade includes the ex-type strain of Cephalosporium serrae var. fuscum (CBS 560.65, Sukapure & Thirumalachar 1966), which we have demonstrated is a different species from C. serrae (treated here as Gibellulopsis serrae), the new combination Gibellulopsis fusca is proposed. Strains CBS 560.65 and CBS 120818 were also studied by Zare et al. (2007), who demonstrated their genetic differences from G. nigrescens and G. piscis (treated here as G. serrae) in ITS and TEF1-α sequences, as well as their different growth patterns at 27 °C and 33 °C.

Cephalosporium apii (currently Acremonium apii) was described from Apium graveolens based on the strain CBS 130.51 (= ATCC 10837 = IMI 92629), as the causal agent of brown spot of celery (Smith & Ramsey 1951). The species is morphologically similar to G. fusca in the chlamydospore's shape and colour, and in the production of cylindrical septate conidia, which was also noticed by Gams (2017). According to Zare et al. (2007) and Summerbell et al. (2011) the LSU and ITS sequences derived from CBS 130.51 falls with Verticillium albo-atrum, being considered as synonym of this species.

We have sequenced three different batches of CBS 130.51 from the culture collection, obtaining the same molecular results as Zare et al. (2007) and Summerbell et al. (2011). However, the examination of the culture led us to conclude that the strain was swapped at some point before or after it was deposited, since the micromorphology does not match that what was originally described and illustrated as Acremonium apii (Gams 1971).

Gibellulopsis nigrescens (Pethybr.) Zare et al., Nova Hedwigia 85: 477. 2007. Fig. 6.

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Fig. 6

Gibellulopsis nigrescens (ex-neotype CBS 120949). A. Colony on PDA after 14 d at 25 °C. B–D. Conidiophores. E. Chlamydospores. F. Conidia. Scale bars: B = 20 μm; C–F = 10 μm.

Basionym: Verticillium nigrescens Pethybr., Trans. Brit. Mycol. Soc. 6: 177. 1919.

Synonym: Verticillium dahliae f. zonatum J.F.H. Beyma, Antonie van Leeuwenhoek 6: 43. 1940.

Mycelium consisting of branched, septate, smooth, hyaline and thin-walled hyphae, up to 2 μm wide. Conidiophores arising from submerged or superficial hyphae, (sub-)erect, mostly irregularly branched, bearing 1–4 levels with 1–3 phialides per node, ca. up to 100 μm long, 1.5–2.5 μm wide at the base, hyaline, smooth-walled, with cell walls usually thicker than those of the vegetative hyphae. Phialides terminal, lateral, aculeate, hyaline, thick- and smooth-walled, 21–44 μm long, 1–2 μm wide at the base, with conspicuous collarette and a distinct periclinal wall thickening at the conidiogenous locus. Conidia cylindrical with rounded ends, sometimes with a slightly protuberant basal end, 1-celled, hyaline, becoming pale brown with age, thin- and smooth-walled, 4.1–5.6 × 1.6–2.3 μm, arranged in slimy heads. Chlamydospores terminal, lateral or intercalary, mostly single, globose to subglobose, olivaceous brown, smooth- and thick-walled, 4.1–6.1 × 3.7–4.6 μm. Sexual morph not observed.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 47‒53 mm diam, flat, finely floccose, olivaceous black with a smoke-grey mycelium at centre and white towards the periphery, reverse olivaceous grey to black. On OA reaching 38‒40 mm diam, flat, membranous, surface and reverse greenish black. On PCA reaching 18‒19 mm diam, flat, glabrous, surface and reverse greenish black. On MEA reaching 30‒33 mm diam, radially folded, felty, with white, buff and grey concentric rings, reverse iron grey.

Specimens examined: Denmark, Klippinge, from Linum usitatissimum, 1964, A. Jensen CBS 469.64. Finland, from moisture damaged building insulator wool, unknown date, VTT, CBS 123176. France, from Medicago sativa, idem., A. Jensen, CBS 470.64. Israel, Kerem-Shalom, from Solanum tuberosum, 1994‒1996, N. Korolev, CBS 100829, CBS 100844; Lahav, from soil, idem., CBS 100832, CBS 10833. Netherlands, Baarn, from soil under lawn, Feb. 2007, W. Gams (neotype of Verticillium nigrescens CBS-H 19845, culture ex-neotype CBS 120949, designated in Zare et al. 2007); Kwade Hoek, from sandy soil, 2002, F.X. Prenafeta-Boldú, CBS 110719; Rotterdam, from wrapping material, unknown date and collector (holotype of Verticillium dahliae f. zonatum CBS 179.40 culture permanently preserved in a metabolically inactive state) culture ex-type CBS 179.40 = MUCL 9783; from nail, unknown date, A. van Duin, CBS 119666. UK, soil under Humulus lupulus, idem., I. Isaac, CBS 577.50; from Solanum tuberosum, idem., I. Isaac, CBS 455.51 = MUCL 9790.

Notes: This species was originally described as Verticillium nigrescens from potato tubers in England (Pethybridge 1919) and later on, neotypified with a soil isolate (CBS 120949) from the Netherlands (Zare et al. 2007). However, Zare et al. (2007) demonstrated that it is not congeneric with Verticillium s. str., being conspecific with the type species of Gibellulopsis, G. piscis. As a consequence, the new combination Gibellulopsis nigrescens, was introduced. The isolates studied by Zare et al. (2007) were phenotypically and genetically variable, clustering in different subclades according to partial TEF1-α sequences. One of them comprised the ex-types of Cephalosporium serrae CBS 290.30 and G. piscis CBS 892.70, and other one held the neotype of G. nigrescens. The authors did not consider those differences significant enough to justify renaming those clades and they treated all isolates as G. nigrescens. According to our multilocus phylogenetic analyses and morphological examination, these subclades correspond to G. serrae and G. nigrescens, respectively (Fig. 1).

Gibellulopsis serrae (Maffei) Giraldo López & Crous, comb. nov. MycoBank MB828040. Fig. 7.

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Fig. 7

Gibellulopsis serrae. B, D, G. CBS 892.70. A, C, E, F. CBS 101221. H. CBS 565.78C. A. Colony on OA after 14 d at 25 °C. B–D. Conidiophores. E, F. Chlamydospores. G, H. Conidia. Scale bars = 10 μm.

Basionym: Cephalosporium serrae Maffei, Atti Ist. Bot. Pavia. Ser. 4: 196. 1930.

Synonyms: Verticillium serrae (Maffei) F.H. Beyma, Antonie van Leeuwenhoek 6: 40. 1939.

Hyalopus serrae (Maffei) Barbosa, Subsidios para o Estudo parasitologico do Genero Hyalopus. Thesis, Recife: 19. 1941.

Verticillium amaranthi Verona & Ceccar., Phytopathol. Z. 8: 373. 1935 (as ‘amaranti’).

Gibellulopsis piscis Bat. & H. Maia, Anais. Soc. Biol. Pernambuco 16: 156. 1959.

Mycelium consisting of branched, septate, hyaline, smooth- and thin-walled hyphae, up to 2 μm wide. Conidiophores arising from submerged or superficial hyphae, (sub-)erect, simple or branched, bearing 1–2 levels with 2–3 phialides per node, ca. up to 300 μm long, 2.5–3 μm wide at the base, hyaline, smooth-walled, with cell walls usually thicker than those of the vegetative hyphae. Phialides terminal, lateral, cylindrical or aculeate, hyaline, thick- and smooth-walled, 23–72 μm long, 1.5–2 μm wide at the base, with inconspicuous collarette and a distinct periclinal thickening at the conidiogenous locus. Conidia ellipsoidal to cylindrical with rounded ends, 1-celled, hyaline, thin- and smooth-walled, 3.5–7.4 × 1.7–2.3 μm, arranged in slimy heads. Chlamydospores mostly intercalary, singly or in pairs, globose to subglobose with a truncate base, pale brown, smooth- and thick-walled, 5–5.5(–7) × 2(–2.5)–5 μm. Sexual morph not observed.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 50‒65 mm diam, flat, felty or floccose, completely white or pale mouse grey at centre and colourless to the periphery, reverse uncoloured or dark mouse grey. On OA reaching 42‒50 mm diam, flat, felty at centre, glabrous or membranous at periphery, slightly zonate, entire margin, white, reverse uncoloured. On PCA reaching 30‒42 mm diam, flat, glabrous or membranous to finely floccose, entire margin white, reverse uncoloured. On MEA reaching 28‒30 mm diam, raised, felty to downy, entire margin, white, reverse uncoloured. In cultures older than 20 d the reverse becomes more or less dark grey due to formation of chlamydospores.

Specimens examined: Argentina, Buenos Aires, from seed, unknown date and collector, CBS 493.82B, CBS 493.82D; Chaco, idem., CBS 493.82C; Misiones, from soil, unknown date and collector, CBS 493.82A. Brazil, Recife, from granuloma in goldfish (Carassius auratus), 28 Jul. 1957, Batista (holotype of Gibellulopsis piscis I.M.U.R. 891, culture ex-type CBS 892.70 = ATCC 16168 = IFO 6653). Canada, Quebec, from Beta vulgaris var. altissima, unknown date and collector, CBS 383.66. Cuba, Santiago de Las Vegas, from seed of Abelmoschus esculentus, unknown date, R.F. Castañeda, CBS 392.89 = INIFAT C88-362. Germany, from Solanum tuberosum, idem., K.H. Schramm, CBS 175.75 = BBA 12362. Greece, Thessaloniki, from human blood, idem., E. Roilides, CBS 109724. India, Bangoan, from leaf of Musa sp., unknown date and collector, CBS 120008; unknown, substrate, date and collector, CBS 416.76. Israel, Ein-Shemer, from soil, 1994‒1996, N. Korolev, CBS 100830, CBS 100831; from soil in cotton field, idem., CBS 101221; Gilat, from Solanum tuberosum, idem., CBS 100826; Ramat-David, from soil in cotton field, idem., CBS 100827. Italy, from human eye, unknown date, G.M. Serra (holotype of Cephalosporium serrae CBS 290.30 culture permanently preserved in a metabolically inactive state) culture ex-type CBS 290.30 = MUCL 7973; from Amaranthus tricolor, unknown date, O. Verona (holotype of Verticillium amaranthi CBS H-19312, culture ex-type CBS 387.35 = MUCL 9784). Japan, from Solanum tuberosum, unknown date and collector, CBS 120177 = NBRC 32001. Moldavia, from Cercospora beticola, idem., CBS 565.78B = VKM F-481. New Zealand, Havelock North, from soil, idem., CBS 125.79. Russia, Astrakhan, from Erysiphe sp., idem., CBS 565.78C = VKM F-241; Odessa, from Oidium sp., idem., CBS 565.78A = VKM F-53. Sweden, from wood pulp, idem., CBS 345.39.

Notes: Most of the isolates in this clade were previously identified as Gibellulopsis nigrescens. However, the neotype of that species falls in a different clade, and therefore, these isolates represent a species distinct from G. nigrescens. This clade harbours the ex-types of Cephalosporium serrae CBS 290.30, G. piscis CBS 892.70 and Verticillium amaranthi CBS 387.35, which were previously considered as synonyms of G. nigrescens (Zare et al. 2007). Since C. serrae is the oldest epithet, we propose G. serrae comb. nov. for the isolates included in this clade. Although the isolates in this clade are genetically heterogeneous we were not able to separate them and we prefer to keep them as a single species until more studies are performed.

Clade II

Furcasterigmium Giraldo López & Crous gen. nov. MycoBank MB828041.

Etymology: From the Latin furcatus, meaning fork, and modern Latin, from Greek stērigma, meaning support. In reference to the forked-like appearance of the conidiogenous cell characteristically formed by these fungi.

Mycelium consisting of branched, septate, hyaline and thick-walled hyphae. Conidiophores erect, unbranched or poorly branched, often proliferating sympodially, showing conidiogenous cells as short lateral and cylindrical asymmetrical projections. Conidiogenous cells enteroblastic, mono- and polyphialidic, terminal, lateral, subulate, hyaline, with conspicuous collarette and periclinal thickening at the conidiogenous locus. Conidia ellipsoidal, 1-celled, hyaline, smooth-walled, arranged in slimy heads. Sexual morph unknown.

Type species: Furcasterigmium furcatum (W. Gams) Giraldo López & Crous.

Furcasterigmium furcatum (W. Gams) Giraldo López & Crous, comb. nov. MycoBank MB828042. Fig. 8.

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Fig. 8

Furcasterigmium furcatum (ex-type CBS 122.42). A. Colony on MEA after 14 d at 25 °C. B–F. Conidiophores. G, H. Slimy heads. I. Conidia. Scale bars = 10 μm.

Basionym: Acremonium furcatum W. Gams, Nova Hedwigia 18: 3. 1969.

Synonym: Cephalosporium furcatum Moreau & R. Moreau, Rev. Mycol. 6: 65. 1941. Nom. inval., Art. 39.1 (Melbourne).

Mycelium consisting of branched, septate, hyaline and thick-walled hyphae, 2–2.5 μm wide. Conidiophores erect, unbranched or proliferating sympodially, showing conidiogenous cells as short lateral and cylindrical asymmetrical projections, up to 36 μm long, 2.5 μm wide at the base, hyaline, smooth-walled. Phialides lateral, terminal, subulate, hyaline, thick- and smooth-walled, 18‒36 μm long, 2–2.5 μm wide at the base, with cylindrical collarette and conspicuous periclinal thickening at the conidiogenous locus, polyphialides with up to three conidiogenous loci commonly present. Conidia ellipsoidal, sometimes with a slightly apiculate base, 1-celled, hyaline, thick- and smooth-walled, 2.7–3.8 × 1.5–2.1 μm, arranged in slimy heads. Sexual morph unknown.

Culture characteristics: After 14 d at ca. 25 °C: On OA reaching 35‒41 mm diam, flat, dusty, dirty white, reverse uncoloured. On MEA reaching 26‒35 mm diam, radially folded, hairy at the centre, floccose at periphery, entire margin, dirty white, reverse uncoloured.

Specimens examined: France, Normandie, Pointe du Siège, from young dunes under Calystegia soldanella, unknown date and collector (holotype of Cephalosporium furcatum CBS 122.42 culture permanently preserved in a metabolically inactive state) culture ex-type CBS 122.42 = IAM 14647 = MUCL 9745. Germany, from Loamy löss soil, unknown date, A. von Klopotek, CBS 299.70C; Kr. Plön, Schüttbrehm, from Gymnopilus sp., unknown date and collector CBS 299.70F; Lübeck, from moist house, unknown date, R.A. Samson, CBS 116550. Iran, from Vitis vinifera, Aug. 2004, T. Gräfenhan & R. Zare, CBS 116548. Italy, Turin, from agricultural soil, unknown date and collector, CBS 299.70A.

Notes: Twenty isolates labelled as Acremonium furcatum were included in this study. They were genetically heterogenous and were distributed in different clades along the tree (Fig 1). Six of them, including the ex-type CBS 122.42, formed a monophyletic lineage (100 % BS) within clade II which is proposed here as the new monotypic genus, Furcasterigmium. The remaining isolates were placed in the clades representing the genera Chordomyces, Theobromium and Phialoparvum, which will be discussed below.

Furcasterigmium furcatum was originally described as Cephalosporium furcatum from young dunes in France (Moreau & Moreau 1941), but invalidly published because of the lack of a Latin diagnosis. The species was validated by Gams (Gams & Domsch 1969) and transferred to the genus Acremonium as one of the species from the section Nectrioidea (Gams 1971). Among the species in that section, A. furcatum resembles A. hyalinulum in the production of schizophialides, but the conidia of the latter species are arranged in chains. According to Gams (1971), A. furcatum sometimes produces synnemata in culture, linking the species with Tilachlidium. However, no synnemata were observed by us among the representative isolates of Furcasterigmium.

Summerbellia Giraldo López & Crous, gen. nov. MycoBank MB828043.

Etymology: In honour of Richard Summerbell, who made a huge contribution towards the modern taxonomy of Acremonium species.

Mycelium consisting of branched, septate, hyaline and thick-walled hyphae. Conidiophores erect or (sub-)erect, unbranched or poorly branched. Conidiogenous cells enteroblastic, monophialidic, terminal, lateral, sub-cylindrical, hyaline, with minute cylindrical collarette, and an inconspicuous periclinal thickening at the conidiogenous locus. Conidia ellipsoidal or cylindrical, 1-celled, hyaline, smooth-walled, arranged in slimy heads. Chlamydospores terminal or intercalary, mostly in chains, pale to dark brown, smooth- and thick-walled. Sexual morph unknown.

Types species: Summerbellia oligotrophica Giraldo López & Crous.

Summerbellia oligotrophica Giraldo López & Crous, sp. nov. MycoBank MB828044. Fig. 9.

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Fig. 9

Summerbellia oligotrophica (ex-type CBS 657.94). A. Colony on MEA after 14 d at 25 °C. B–D. Conidiophores. E. Chlamydospores. F, G. Conidia. Scale bars: B–D, F, G = 10 μm; E = 5 μm.

Etymology: Referring to the oligotrophic nature of the fungus.

Mycelium consisting of branched, septate, hyaline and thick-walled hyphae, up to 2 μm wide. Conidiophores erect or (sub-)erect, simple or poorly branched, up to 50 μm long, 2 μm wide at the base, hyaline, smooth-walled. Phialides terminal, lateral, sub-cylindrical, hyaline, thin- and smooth-walled, often borne on short cylindrical subtending cells; 13–50 μm long, 1.5–2 μm wide at the base, with minute cylindrical collarette, and an inconspicuous periclinal thickening at the conidiogenous locus. Conidia ellipsoidal or cylindrical, 1-celled, hyaline, thin- and smooth-walled, 2.3–4.3 × 1.2–2 μm, arranged in slimy heads. Chlamydospores, terminal or intercalary, mostly in chains, subglobose, light to dark brown, smooth- and thick-walled, 3–4 × 3–4 μm.

Culture characteristics: After 14 d at ca. 22 °C: On OA attaining 40‒44 mm diam, flat, dusty, dirty white, reverse slightly buff. On MEA attaining 35‒38 mm diam, raised, radially folded, hairy, diffuse margin, buff, uncoloured reverse.

Specimens examined: Australia, New South Wales, unknown substratum, date and collector, CBS 620.76. Indonesia, from alkaline soil, unknown date, K. Nagai (holotype CBS-H-23648, culture ex-type CBS 657.94). USA, Florida, from grapefruit juice can, unknown date and collector, CBS 299.70G = QM 2995; from bath towel, idem., CBS 299.70H = QM 3222.

Notes: The genus Summerbellia is proposed here for a group of isolates clustering in a well-supported monophyletic lineage in clade II (Fig. 1). All isolates were previously identified as Gliocladium cibotii based on morphological characters. However, the ex-type strain of this species falls in a phylogenetically distant clade (named here Brunneochlamydosporium). In addition, G. cibotii differs by having a faster growth rate on OA and MEA, frequently branched conidiophores, and larger conidia and chlamydospores than those of S. oligotrophica.

Among the isolates included in Summerbellia, CBS 657.94 and CBS 299.70H were also treated by Zare et al. (2007), who found them to be genetically different from the ex-type strain of G. cibotii. However, the authors could not correlate the molecular difference with any phenotypic feature.

Musidium Giraldo López & Crous gen. nov. MycoBank MB828045.

Etymology: From Latin Musa, meaning banana, the most frequent host.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae. Conidiophores erect, unbranched or poorly branched. Conidiogenous cells enteroblastic, monophialidic, terminal, lateral, subulate, hyaline, with short cylindrical collarette, and with a distinct periclinal thickening at the conidiogenous locus. Conidia cylindrical or ellipsoidal, 1-celled, hyaline, smooth-walled, arranged in slimy heads. Stromatic hyphae branched or unbranched, dark olivaceous, incrusted or smooth and thick-walled, produced on the bottom of plate cultures or at the edge of agar slants. Sexual morph unknown.

Type species: Musidium stromaticum (W. Gams & R.H. Stover) Giraldo López & Crous.

Musidium stromaticum (W. Gams & R.H. Stover) Giraldo López & Crous, comb. nov. MycoBank MB828046. Fig. 10.

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Fig. 10

Musidium stromaticum (ex-type CBS 863.73). A. Colony on PDA after 14 d at 25 °C. B–D. Poorly branched conidiophores with percurrent proliferations. E, F. Stromatic hyphae. G. Conidia. Scale bars = 10 μm.

Basionym: Acremonium stromaticum W. Gams & R.H. Stover, Trans. Brit. Mycol. Soc. 64: 400. 1975.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae, 2–2.5 μm wide. Conidiophores erect, lateral, unbranched or basitonously branched, up to 59 μm long, 2.5 μm wide at the base, hyaline, smooth-walled, with cell walls usually thicker than those of the vegetative hyphae. Conidiogenous cells lateral, subulate, hyaline, thick- and smooth-walled, 23–55 μm long, 2–2.5 μm wide at the base, with cylindrical collarette, and with a distinct periclinal thickening at the conidiogenous locus, commonly with a percurrent proliferation. Conidia cylindrical with rounded ends or ellipsoidal, 1-celled, hyaline, thin- and smooth-walled, 4.2–6.2 × 1.4–2.3 μm, arranged in slimy heads. Stromatic hyphae branched, dark olivaceous, smooth- and thick-walled, produced on the bottom of plate cultures or at the edge of agar slants. Sexual morph unknown (Adapted from Gams 1975).

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 70‒71 mm diam, flat, felty, fimbriate margin, dirty white, reverse uncoloured. On OA reaching 69‒72 mm diam, flat, membranous with scarce aerial mycelium, dirty white, reverse uncoloured. On MEA reaching 28‒42 mm diam, flat, wrinkled, woolly to cottony, filiform margin, dirty white, reverse gradually becoming dark grey by the stromatic tissue.

Specimens examined: Colombia, Turbo, from Musa sp., unknown date, R.H. Stover, CBS 135.74D. Costa Rica, Coto valley, idem., CBS 132.74, CBS 133.74. Honduras, Lula valley, idem., unknown date, R.H. Stover, CBS 134.74, CBS 135.74C; from Musa sapientum root lesions, Dec. 1962, R.H. Stover (isotype IMI 185381, culture ex-type CBS 863.73 = ATCC 32187). Panama, Changumola, from Musa sp., unknown date, R.H. Stover, CBS 135.74A. Philippines, Mindanao, from rhizosphere of Musa sp., idem., R.H. Stover, CBS 135.74F. Tanzania, from Musa sp., 1953, G.B. Wallace, CBS 135.74H. UK, England, Kew, Royal Botanical Gardens, from leaf of Musa sp. (in a greenhouse), 1969, W. Gams, CBS 135.74G.

Notes: The monotypic genus Musidium is established here to accommodate a group of isolates previously classified as Acremonium stromaticum, which was described based on isolates from Musa sp. in Honduras (Gams 1975). The genus formed a well-supported clade (99 % BS), closely related (Fig. 1) to Sayamraella, Summerbellia and Theobromium (94 % BS), but morphologically differentiable by the production of branched stromatic hyphae. All the isolates in this clade are from root and rhizome lesions from banana growing in the tropics, specially from Central America, except CBS 135.74G which comes from Europe and is placed in a separate branch, basal to the clade containing the tropical isolates. All the isolates included in Musidium stromaticum were studied by Stover (1966), who treated them as Cephalosporium sp. Stover (1966) commonly recorded the isolates in lesions produced by the nematode Rodopholus similis, and stated that they can constitute up to 50 % of the isolates in such lesions in some areas. Attempts to grow the species are not always successful, since the host material (roots and rhizomes) must to be macerated before plating (Gams 1975).

Sayamraella Giraldo López & Crous, gen. nov. MycoBank MB828047.

Etymology: Name derived from the combination of Sayam and Ra; in Thai meaning Thailand and fungus, respectively; where this fungus was first discovered.

Mycelium consisting of branched, septate, hyaline and thick-walled hyphae. Conidiophores erect, unbranched or poorly branched, often proliferating sympodially, showing conidiogenous cells as short lateral and cylindrical asymmetrical projections. Conidiogenous cells enteroblastic, mono- and polyphialidic, terminal, lateral, subulate, hyaline, with minute cylindrical collarette, and an inconspicuous periclinal thickening at the conidiogenous locus. Conidia ellipsoidal, 1-celled, hyaline, smooth-walled, arranged in slimy heads. Sexual morph unknown.

Type species: Sayamraella subulata Giraldo López & Crous.

Sayamraella subulata Giraldo López & Crous, sp. nov. MycoBank MB828048. Fig. 11.

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Fig. 11

Sayamraella subulata (ex-type BCC 78964). A. Colony on PDA after 14 d at 25 °C. B–D. Simple conidiophores. E, F. Polyphialides. G. Phialide with minute collarette. H. Conidia. Scale bars = 10 μm.

Etymology: Referring to the subulate shape of its phialides.

Mycelium consisting of branched, septate, hyaline and thick-walled hyphae, 2–2.5 μm wide. Conidiophores erect, unbranched or poorly branched, often proliferating sympodially, showing conidiogenous cells as short lateral and cylindrical asymmetrical projections, up to 74 μm long, 3 μm wide at the base, hyaline, smooth-walled. Phialides terminal, lateral, subulate, hyaline, thin- and smooth-walled, 20.3–73.7 μm long, 2.1–3 μm wide at the base, with minute cylindrical collarette, and an inconspicuous periclinal thickening at the conidiogenous locus, polyphialides with up to two conidiogenous loci commonly present. Conidia ellipsoidal, 1-celled, hyaline, thin- and smooth-walled, 3.6–4.7 × 1.7–2.4 μm, arranged in slimy heads. Sexual morph unknown.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 60‒64 mm diam, flat, floccose to woolly, dirty white, reverse uncoloured, strong geosmin odour. On OA reaching 49‒50 mm diam, flat, floccose at centre with concentric rings at periphery, dirty white, reverse uncoloured.

Specimen examined: Thailand, Lopburi province, Wang Kan Lueang waterfall, from soil around Hopea odorata, 14 Jul. 2015, A. Giraldo (holotype BCC 78964 culture permanently preserved in a metabolically inactive state) culture ex-type BCC 78964.

Notes: Sayamraella subulata is introduced as a monotypic genus for a fungus isolated from soil collected around roots of Hopea odorata in Thailand. The isolate clustered in a single branch within clade II, separated from, but related to, Summerbellia, Musidium and Theobromium (Fig. 1).

Theobromium Giraldo López & Crous, gen. nov. MycoBank MB828049.

Etymology: From Latin Theobroma, meaning cacao, the source of isolation of the ex-type strain.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae, becoming light brown and thick-walled with age. Conidiophores erect, unbranched or poorly branched, often proliferating sympodially, showing conidiogenous cells as short lateral and cylindrical asymmetrical projections. Conidiogenous cells enteroblastic, mono- and polyphialidic, lateral, subulate, hyaline, with minute cylindrical collarette, and an inconspicuous periclinal thickening at the conidiogenous locus. Conidia cylindrical or ellipsoidal, 1-celled, hyaline, smooth-walled, arranged in slimy heads. Sexual morph unknown.

Type species: Theobromium fuscum Giraldo López & Crous.

Theobromium fuscum Giraldo López & Crous, sp. nov. MycoBank MB828050. Fig. 12.

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Fig. 12

Theobromium fuscum (ex-type CBS 112271). A. Colony on MEA after 14 d at 25 °C. B. Simple conidiophore. C. Conidiophores with percurrent proliferation. D. Polyphialides. E, F. Hyphae. G. Conidia. Scale bars = 10 μm.

Etymology: From Latin fuscus, meaning brownish. Referring to the production of brownish pigmented hyphae.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae, 2–2.5 μm wide, becoming pale brown (especially at the septa) and thick-walled with age, 2.4–4 μm wide. Conidiophores erect, unbranched or basitonously branched, bearing up to two phialides, commonly proliferating sympodially, showing conidiogenous cells as short lateral and cylindrical asymmetrical projections, up to 57 μm long, 3 μm wide at the base, hyaline, smooth-walled. Phialides lateral, subulate, hyaline, thin- and smooth-walled, 23–38 μm long, 2–3 μm wide at the base, with minute cylindrical collarette, and an inconspicuous periclinal thickening at the conidiogenous locus, commonly with a percurrent proliferation, polyphialides with up to two conidiogenous loci. Conidia cylindrical or ellipsoidal, 1-celled, hyaline, thin- and smooth-walled, 2.7–4.1 × 1.3–2 μm, arranged in slimy heads. Sexual morph unknown.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 38‒44 mm diam, flat, floccose at centre, diffuse margin, dirty white, reverse uncoloured. On OA reaching 38‒40 mm diam, flat, felty at the inoculation point, membranous at the periphery, dirty white, reverse uncoloured. On MEA reaching 31‒34 mm diam, raised, radially folded, felty to powdered, dirty white to pale luteous, with an amber exudate and strong geosmin odour.

Specimen examined: Ecuador, Pichincha province, Vicente Maldonado, from Theobroma sp., unknown date, H.C. Evans & K.A. Holmes (holotype CBS H-23657, culture ex-type CBS 112271).

Notes: The monotypic genus Theobromium is proposed here to accommodate a single strain, isolated from Theobroma sp., that is phylogenetically related (94 % BS) with Summerbellia, Musidium and Sayamraella. Theobromium fuscum resembles Sayamraella subulata in the production of polyphialides and conidial morphology. However, the former species has phialides with percurrent proliferation, shorter conidiophores and conidia, and a slower growth rate than Sayamraella subulata.

Clade III

Chordomyces Bilanenko et al., Fungal Diversity 76: 55. 2016.

Mycelium consisting of septate, hyaline, thin- and smooth-walled hyphae. Conidiophores erect, solitary or forming synemata, unbranched or branched. Synnemata when present sometimes branched, indeterminate, fimbriate, hyaline. Conidiogenous cells enteroblastic, mono- or polyphialidic, tapering towards the apex, hyaline, often proliferating sympodially. Conidia subglobose, limoniform, ellipsoidal to cylindrical, rounded at the apex, sometimes with protuberant hilum, 1(‒2)-celled, hyaline, smooth-walled, arranged in slimy heads. Sexual morph unknown. Description adapted from that of Giraldo et al. 2017.

Type species: Chordomyces antarcticus Bilanenko et al.

Chordomyces albus Giraldo et al., Mycol. Progr. 16: 359. 2017.

Specimens examined: Belgium, Heverlee, from garden soil, 1964, G.L. Hennebert, CBS 741.69. France, Grignon from agricultural soil, unknown date and collector, CBS 299.70E. Germany, Kiel, Botanical Garden, from moist wall, 1965, W. Gams, CBS 206.70; Bottsand, from rhizosphere soil of Ammophila arenaria, idem., CBS 205.70; Kitzeberg, from dead stem of Angelica archangelica, idem., CBS 204.70. Ireland, from peat, unknown date, C.H. Dickinson, CBS 742.69. Luxembourg, Hautecharage, on Hypogymnia physodes, Dec. 1987, G. Marson (holotype CBS H-8083, culture ex-type CBS 987.87 = FMR 10886). Netherlands, Baarn, on dead leaf of Canna indica, 21 May 1968, W. Gams, CBS 409.70; from forest humus soil, 1964, G.L. Hennebert, CBS 508.65; Wageningen, from soil, unknown date, J.H. van Emden, CBS 743.69. UK, England, Egham, on leaf litter of Viscum album, unknown date, T. Gräfenhan & W. Gams, CBS 580.97.

Notes: Chordomyces albus is the second species described in the genus, from a lichen in Luxembourg (Giraldo et al. 2017). In our study, all the isolates placed in C. albus clade (CBS 204.70, CBS 205.70, CBS 206.70, CBS 299.70E, CBS 409.70, CBS 508.65, CBS 580.97, CBS 741.69, CBS 742.69 and CBS 743.69) were formerly identified as Acremoniun furcatum, which is treated here as Furcasterigmium furcatum. Both species share the conidial morphology and the production of polyphialides. However, in C. albus the polyphialides have up to two conidiogenous loci, while in F. furcatum they have maximum three conidiogenous loci.

The distribution of C. albus seems to be restricted to Europe and the USA, commonly being isolated from soil, but also found in Canna indica (Cannaceae), Viscum album (Santalaceae) and Angelica archangelica (Apiaceae). Only one isolate is presently known from human sources; it was isolated from sputum in the USA (Giraldo et al. 2017).

Chordomyces antarcticus Bilanenko et al., Fungal Diversity 76: 57. 2016.

Description and illustrations: Grum-Grzhimaylo et al. (2016).

Specimens examined: Kazakhstan, from Suaeda salsa on the coast of the Aral lake, Dec. 2003, F.V. Sapozhnikov, CBS 137610 = A141. Mongolia, North Gobi, Bayan-Zag area, from soda soil, Aug. 2003, I.A. Yamnova, CBS 120042 = M10 = VKM FW-3039. Portugal, Lisboa, from cork, unknown date and collector, CBS 610.69. Russia, Altai, Kulunda steppe, from soda soil at the edge of Berdabay lake, Aug. 2005, D.Y. Sorokin, CBS 137607 = A135; at the edge of Bezimyannoe lake, Aug. 2002, D.Y. Sorokin, CBS 137630 = V213; at the edge of Karakul Lake, Nov. 2002, M. Georgieva (holotype CBS H-21956, culture ex-type CBS 120045 = VKM FW-3041); at the edge of Petuchovskoe lake, Aug. 2002, D.Y. Sorokin, CBS 137606 = A134; at the edge of Solyonoe lake, idem., CBS 120047 = M31 = VKM FW-3906; at the edge of Uzkoe lake, idem., CBS 120046 = M30 = VKM FW3042.

Notes: The genus Chordomyces was introduced by Grum-Grzhimaylo et al. (2016) based on C. antarcticus as type species, isolated from soda soils of Russia. The genus was recently emended by Giraldo et al. (2017) to include species with subglobose to limoniform conidia. The majority of isolates of C. antarcticus were recovered from soils with a pH ranging from 8.9 to 10.1, and were alkalitolerant according to Grum-Grzhimaylo et al. (2016).

Clade IV

Plectosphaerella Kleb., Phytopathol. Z. 1: 43. 1930.

Ascomata perithecial, solitary or gregarious, superficial, subglobose to pyriform, dark-brown in the basal part, paler at the neck, with or without sparse setae around the base of the neck, surface with textura angularis. Setae cylindrical with wider base, rounded to pointed ends, golden brown, thick- and smooth-walled. Asci unitunicate, cylindrical, clavate, thin-walled, lacking an apical differentiation, 8-spored. Ascospores ellipsoidal, 2-celled, hyaline, smooth to slightly warted. Conidiophores simple and poorly branched, hyaline, smooth, thin-walled. Conidiogenous cells enteroblastic, mono- and polyphialidic, terminal, lateral, cylindrical, tapering gradually towards the apex, hyaline, with cylindrical collarette and conspicuous periclinal thickening at the conidiogenous locus. Conidia cylindrical 1- or 2-celled, hyaline, smooth-walled, arranged in slimy heads (adapted from Uecker, 1993, Domsch et al., 2007 and Zare et al. 2007).

Type species: Plectosphaerella cucumerina (Lindf.) W. Gams.

Plectosphaerella cucumerina (Lindf.) W. Gams, Persoonia 5: 179. 1968. Fig. 13.

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Fig. 13

Plectosphaerella cucumerina. A–E. Sexual morph (ex-neotype CBS 131739). F–K. Asexual morph (CBS 137.37). A–C. Sporulating ascomata on OA. D, E. Details of the ostiolar region and peridium, respectively. F–H. Monophialides (note the microcyclic conidiation on F). I. Polyphialide. J, K. Septate and aseptate conidia. Scale bars = 10 μm.

Basionym: Venturia cucumerina Lindf., Meddn. CentAnst. FörsVäs. JordbrOmrad., Stockholm 193/17: 7. 1919.

Synonyms: Monographella cucumerina (Lindf.) Arx, Trans. Brit. Mycol. Soc. 83: 374. 1984.

Plectosphaerella cucumeris Kleb., Phytopathol. Z. 1: 43. 1930.

Micronectriella cucumeris (Kleb.) C. Booth, The genus Fusarium: 39. 1971.

Cephalosporium tabacinum J.F.H. Beyma, Zentralbl. Bakteriol., 2 Abt. 89: 240. 1933.

Fusarium tabacinum (J.F.H. Beyma) W. Gams, Persoonia 5: 179. 1968.

Microdochium tabacinum (J.F.H. Beyma) Arx, Trans. Brit. Mycol. Soc. 83: 374. 1984.

Plectosporium tabacinum (J.F.H. Beyma) M.E. Palm, W. Gams & Nirenberg, Mycologia 87: 399. 1995.

Cephalosporium ciferrii Verona, Studio sulle cause microbiche che dannegiano la carte ed I libri, Roma: 30. 1939.

Cephalosporiopsis imperfecta Moreau & R. Moreau, Rev. Mycol. 6: 67.1941. Nom. inval., Art. 39.1 (Melbourne).

Descriptions and illustrations: Domsch et al., 2007, Carlucci et al., 2012.

Specimens examined: Belgium, Heverlee, from Nicotiana tabacum rootlet in greenhouse, unknown date and collector, CBS 286.64. Canada, from Solanum lycopersicon, unknown date and collector, CBS 400.58; Alberta, from leaf and stem of Galium spurium, unknown date, W. Zhang, CBS 101958. Egypt, from Viola odorata, unknown date and collector, CBS 367.73 = IMI 151458. Italy, Foggia, Borgo Cervaro, from collar of Cucumis melo, 2004, A. Carlucci (neotype of Venturia cucumerina designated here CBS H-20896, MBT383650, culture ex-neotype CBS 131739 = Plect 11); unknown locality, from paper, unknown date, O. Verona, (holotype of Cephalosporium ciferri CBS 137.37 culture permanently preserved in a metabolically inactive state) culture ex-type CBS 137.37 = MUCL 9704. Netherlands, from root of Viola tricolor, idem., T. van Eek, CBS 355.36. Switzerland, Basel, from leaf of Pyrus malus, 3 Oct 1974, F. Stadelmann, CBS 619.74; unknown locality, from Arabidopsis sp., unknown date, B. Mauch-Mani, CBS 632.94; from Arabidopsis thaliana, idem., CBS 101014. USA, unknown origin and date, M.A. Pisano, CBS 139.60. USSR, from unknown fungus, unknown date and collector, CBS 567.78 = VKM F-156. UK, England, Bristol, from Nicotiana tabacum, unknown date, Jollyman (neotype of Cephalosporium tabacinum CBS H-7656, culture ex-neotype CBS 137.33, designated in Palm et al. 1995).

Notes: Plectosphaerella cucumerina, the type species of Plectosphaerella was originally described as Venturia cucumerina from Cucumis sativus (Cucumeris sativae, in the protologue) in Sweden, based on the sexual morph (Lindfors 1919). The genus Plectosphaerella was established 10 yr later by Klebahn (1929), based on P. cucumeris, also obtained from Cucumis sativus in Germany. Elbakyan (1970) regarded both species as conspecific, but the formal combination, Plectosphaerella cucumerina was only later introduced by Gams (Domsch & Gams 1972). A detailed development study of P. cucumerina was carried out by Uecker (1993), based on isolate CBS 101607 (= ATCC 96328 = G.J.S. 84-531), recovered from Nicotiana tabacum in New Zealand. This isolate was then designated as neotype for both Plectosphaerella cucumeris and Venturia cucumerina (Rossman et al. 1999).

The asexual morph was described as Cephalosporium tabacinum from Nicotiana tabacum (van Beyma 1933), and was then transferred to Fusarium and Microdochium as F. tabacinum (Gams & Gerlagh 1968) and M. tabacinum (von Arx 1984), respectively. Finally, Palm et al. (1995) introduced the genus Plectosporium, based on P. tabacinum with the ex-neotype CBS 137.33. After the abolishment of dual nomenclature, the name Plectosphaerella took priority over Plectosporium.

In our phylogeny, the isolates of P. cucumerina clustered in a single clade (95 % BS), including the ex-type of Plectosporium tabacinum CBS 137.33 and Cephalosporium ciferri CBS 137.37; while the neotype of Venturia cucumerina CBS 101607 falls in the P. plurivora clade (Fig. 1). In order to stabilize the species epithet, which is very important to the plant pathology community, the selection of a new neotype that correctly represents the species is necessary. Among the isolates included in the P. cucumerina clade, CBS 131739 was able to produce the sexual morph in culture (Fig. 13), morphologically matching the protologue of V. cucumerina. Thus, we have selected CBS 131739, from Cucumis melon, grown in Italy, as the neotype of this taxon.

Plectosphaerella humicola Giraldo López & Crous, sp. nov. MycoBank MB828052. Fig. 14.

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Fig. 14

Plectosphaerella humicola (ex-type CBS 423.66). A. Colony on PDA after 14 d at 25 °C. B–D. Monophialides. E–H. Adelophialides. I, J. Polyphialides. K, L. Septate and aseptate conidia, respectively. Scale bars = 10 μm.

Etymology: Name refers to the substrate from which this fungus was isolated, soil.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae. 1.5–2 μm wide. Conidiophores solitary, unbranched or rarely branched, hyaline, smooth, thin-walled, sometimes radiating out from sterile coils formed by the mycelium. Phialides terminal, lateral, cylindrical, sub-cylindrical or ampulliform, hyaline, thick- and smooth-walled, 11–41 μm long, 2.3–3.3 μm wide at the base, with cylindrical collarette and conspicuous periclinal thickening at the conidiogenous locus, adelophialides 2.8–13.7 × 1.5–4 μm, polyphialides with up to two conidiogenous loci commonly present. Septate conidia cylindrical or ellipsoidal, with obtuse apices and apiculate bases, 2-celled, hyaline, thick- and smooth-walled, 7.5–11 × 2.5–3.5 μm, arranged in slimy heads. Aseptate conidia cylindrical or ellipsoidal, acute at apex and base, 1-celled hyaline, thick- and smooth-walled, 5–8 × 2.1–3.3 μm, arranged in slimy heads.

Culture characteristics: After 14 d at ca. 25 °C: On PDA attaining 74–75 mm diam, flat, floccose at centre, membranous at periphery, surface and reverse dirty white. On OA attaining 56–70 mm diam, flat, glabrous, entire margin, pale luteous with ochraceous shades.

Specimen examined: Zaire, Katanga, from soil, unknown date, M. Lanneau (holotype CBS H-23655, culture ex-type CBS 423.66 = DSM 62443 = NRRL 20448.)

Notes: The isolate CBS 423.66 is nestled in the same clade (100 % BS) as P. pauciseptata and P. plurivora. The species can be morphologically distinguished by the colony colour on PDA being buff or pink in P. pauciseptata and P. plurivora, and dirty white in P. humicola. This strain was examined by Gams & Gerlagh (1968), being one of the isolates of P. cucumerina able to produce perithecia in culture. However, the sexual morph was not observed in our study.

Plectosphaerella plurivora A.J.L. Phillips et al., Persoonia 28: 44. 2012. Fig. 15.

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Fig. 15

Plectosphaerella plurivora sexual morph (CBS 101607). A, B. Sporulating ascomata on OA. C. Ascoma releasing the asci. D. Details of the ostiolar region and peridium. E, F. Asci. G. Ascus stained with Melzer’s reagent. H, I. Ascospores. Scale bars: C, D = 20 μm; E–I = 10 μm.

Synonym: Plectosphaerella niemeijerarum L. Lombard, Persoonia 39: 459. 2017.

The description of the sexual morph complements the previous species concept based on the asexual morph (Carlucci et al. 2012), thus providing a holomorphic species concept.

Ascomata perithecial solitary or gregarious, superficial, subglobose to pyriform, dark brown in the basal part, paler at the neck, 100.3–209 × 86–156 μm, without setae around the neck, textura angularis. Asci unitunicate, clavate, thin-walled, lacking iodine reaction, 8-spored, 31.4–43 × 6.2–8.2 μm. Ascospores biseriate, ellipsoidal, 1- or 2-celled hyaline, smooth-walled, 6.1–13.2 × 2.4–3.7 μm. Descriptions and illustrations of the asexual morph: Carlucci et al. (2012).

Specimens examined: Australia, New South Wales, from Lolium perenne, unknown date, M. Priest, CBS 101.87. Belgium, from soil, unknown date and collector, CBS 642.63. Germany, from soil, unknown date, H. Nirenberg, CBS 260.89; idem., CBS 261.89. Italy, Apulia, Borgo Cervaro, on asparagus apex turion, 2006, A. Carlucci (holotype CBS H-20899, culture ex-type CBS 131742); Rignano Garganico, from Solanum lycopersicum, unknown date, A. Carlucci, CBS 131860. Netherlands, Haren, from Solanum tuberosum, unknown date and collector, CBS 406.85; Nieuwegein, from garden soil, Feb. 2017, F. & R. Niemeijer, CBS 143233 = JW 5012 (ex-type of Plectosphaerella niemeijerarum); Oostelijk Flevoland, from agricultural soil, unknown date and collector, CBS 215.84; from wheat field soil, May 1966, W. Gams, CBS 386.68; from soil, 1966, M. Gerlagh, CBS 292.66; from soil, unknown date, G.J. Bollen, CBS 757.68. New Zealand, Auckland, from Nicotiana tabacum, Oct. 1984, G.J. Samuels, CBS 101607 = ATCC 96328 = G.J.S. 84–531. UK, Scotland, Lona, from Solanum tuberosum, unknown date and collector, CBS 417.81. USA, Tennessee, from Solanum tuberosum, unknown date, Wollenweber, CBS 291.38 = ATCC 13425.

Notes: Plectosphaerella plurivora was described from Asparagus by Carlucci et al. (2012), based on the production of the asexual morph. In our study, among the isolates examined, only CBS 101607 from Nicotiana tabacum and CBS 101.87 from Lolium perenne were able to produce the sexual morph in culture. This finding makes P. plurivora the second holomorphic species described in the genus. Strain CBS 101607 was designated by Rossman et al. (1999) as neotype of P. cucumerina, a placement that is rejected by us based on our phylogenetic results (Art. 9.18 Shenzhen Code, see notes under P. cucumerina). Morphologically, the ascomata of Plectosphaerella plurivora are wider, have a darker peridium and a shorter neck than those of P. cucumerina. Although we have not seen setae in these isolates, according to the observations of Uecker (1993) and Palm et al. (1995) a few golden-brown setae were present at the base of the neck of some ascomata formed by those strains. At the same time Palm et al. (1995) stated that the production of setae did not appear to be a stable character.

According to our phylogeny the isolates CBS 101.87, CBS 215.84, CBS 260.89, CBS 261.89, CBS 291.38, CBS 292.66, CBS 386.68, CBS 406.85, CBS 417.81, CBS 642.63, CBS 757.68 and CBS 101607, previously identified as P. cucumerina, are re-identified here as P. plurivora. Among these isolates, CBS 292.66 and CBS 386.68 were examined by Gams & Gerlagh (1968), who found that they were able to produce perithecia in culture at that time.

Plectosphaerella niemeijerarum was recently described from soil in the Netherlands, based on ITS, LSU, TEF1-α and beta-tubulin sequences (Crous et al. 2017). However, the multilocus sequence analysis performed in this study shows this species falls within the range of variation accepted for P. plurivora (Fig. 1).

Brunneochlamydosporium Giraldo López & Crous, gen. nov. MycoBank MB828053.

Etymology: From Latin brunneus = brown, referring to the brownish chlamydospores produced by species in this genus.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae, often becoming pigmented and thick-walled with age. Conidiophores erect, lateral, simple or poorly branched. Conidiogenous cells enteroblastic, monophialidic, sometimes polyphialidic, terminal, lateral, (sub)cylindrical to subulate, hyaline, with conspicuous collarette and a periclinal thickening at the conidiogenous locus. Conidia ellipsoidal, cylindrical, 1-celled, hyaline, smooth-walled, arranged in slimy heads. Chlamydospores lateral, terminal, intercalary, solitary, in pairs or short chains, 1–2-celled, pale to dark brown, smooth- and thick-walled. Sexual morph unknown.

Type species: Brunneochlamydosporium nepalense (W. Gams) Giraldo López & Crous

Brunneochlamydosporium cibotii (J.F.H. Beyma) Giraldo López & Crous, comb. nov. MycoBank MB828054. Fig. 16.

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Fig. 16

Brunneochlamydosporium cibotii (ex-isotype CBS 109240). A. Colony on OA after 14 d at 25 °C. B–C. Conidiophores. D. Adelophialide. E. Hyphae. F. Chlamydospores. G. Conidia. Scale bars = 10 μm.

Basionym: Gliocladium cibotii J.F.H. Beyma, Antonie van Leeuwenhoek 10: 47. 1944.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae, becoming green-brown to brown-black and thick-walled with age, up to 2 μm wide, forming bundles. Conidiophores arising from submerged, erect, simple or poorly branched hyphae, bearing 2‒3 phialides at the middle, up to 84 μm long, 2–2.5 μm wide at the base, hyaline, smooth-walled. Phialides terminal, lateral, cylindrical, hyaline, thick- and smooth-walled, 13–58 μm long, 2 μm wide at the base, with cylindrical to flared collarette and a distinct periclinal thickening at the conidiogenous locus, adelophialides commonly present, up to 7.5 μm long. Conidia ellipsoidal, 1-celled, hyaline, thin- and smooth-walled, 2.9–4.5 × 1.6–2.2 μm, containing two guttules, arranged in slimy heads. Chlamydospores mostly terminal, intercalary, solitary, rarely in pairs, subglobose or obovoid, sometimes 2-celled, pale brown, smooth- and thick-walled, 3.9–6.2 × 2.6–4.3 μm.

Culture characteristics: After 14 d at ca. 25 °C: On OA reaching 60‒65 mm diam, flat, dusty, with concentric rings, buff, reverse isabelline. On MEA reaching 59‒62 mm diam, wrinkled, radially folded, membranous, isabelline at centre and buff at periphery, becoming fuscous black with age, reverse uncoloured. Strong geosmin odour in both media.

Specimen examined: Netherlands, Delft, from Cibotium schiedei, unknown date and collector (isotype CBS H-12850, culture ex-isotype CBS 109240 = DSM 2529 = MUCL 7576).

Notes: Brunneochlamydosporium cibotii was originally described as Gliocladium cibotii by van Beyma (1944) from Cibotium schiedei (Mexican tree fern) in the Netherlands. However, this species is not congeneric with the type species of Gliocladium, G. penicillioides (currently Sphaerostilbella, Lombard et al. 2015), which belongs to Hypocreaceae (Hypocreales, Sordariomycetes). According to our phylogenetic inference the ex-type of G. cibotii CBS 109240 falls in a fully supported clade (100 % BS) together with the ex-isotype of Acremonium nepalense CBS 971.72, and therefore the new genus Brunneochlamydosporium is proposed here to accommodate these taxa. Both species are easily distinguished by their colony colour on OA at 14 d, which is dark grey to almost black with the reverse becoming dark grey in B. nepalense and buff in B. cibotii. In addition, the conidiophores and phialides of B. cibotii are longer than those of B. nepalense.

In the protologue of G. cibotii, van Beyma (1944) described and illustrated the conidiophores as dichotomously bifurcated, arising from pigmented hyphae grouped in bundles, just as we observed here. However, no mention was made of the production of chlamydospores. These structures were observed in the present study after 14 d in all media tested.

Brunneochlamydosporium macroclavatum Giraldo López & Crous, sp. nov. MycoBank MB828055. Fig. 17.

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Fig. 17

Brunneochlamydosporium macroclavatum (ex-type CBS 101249). A. Colony on OA after 14 d at 25 °C. B–C. Conidiophores. D. Polyphialide. E. Adelophialide (arrow). F. Ropes of hyphae. G–H. Chlamydospores. I. Conidia. Scale bars: B, C, F–I = 10 μm. E, F = 5 μm.

Etymology: From Latin macro, meaning large, and clavatus meaning clavate, i.e., club-shaped. Referring to the large and clavate chlamydospores produced by this fungus.

Mycelium consisting of branched, septate, hyaline and thin-walled hyphae, becoming dark brown and thick-walled with age, up to 2 μm wide, forming bundles. Conidiophores arising from submerged, erect, simple or poorly branched hyphae, bearing 2‒3 phialides at the middle, up to 113 μm long, 2–2.5 μm wide at the base, hyaline, smooth-walled. Phialides terminal, lateral, (sub)cylindrical to subulate, hyaline, thick- and smooth-walled, 27–66 μm long, 2–2.5 μm wide at the base, with cylindrical to flared collarette and a distinct periclinal thickening at the conidiogenous locus, adelophialides up to 3 μm long, polyphialides with up to two conidiogenous loci sometimes present. Conidia ellipsoidal, 1-celled, hyaline, thin- and smooth-walled, 4–5.2 × 2–2.5 μm, containing one or two guttules, arranged in slimy heads. Chlamydospores terminal, intercalary, solitary, in pairs or in short chains, subglobose, clavate or pyriform, 1-celled, pale to dark brown, smooth- and thick-walled, 4.6–10 × 3.3–6 μm.

Culture characteristics: After 14 d at ca. 25 °C: On PDA reaching 78‒80 mm diam, flat, floccose to woolly, dirty white with fuscous black shades, reverse fuscous black. On OA reaching 75‒77 mm diam, flat, woolly at centre, floccose at periphery, pale luteous with pale mouse grey shades, reverse mouse grey to fuscous black. On MEA reaching 57‒58 mm diam, flat, wrinkled, radially folded, downy, buff, reverse with fuscous black shades. Strong geosmin odour in all media.

Specimens examined: India, Bangalore, from Salvinia auriculata, unknown date, T. Sankaran, CBS 823.73. Mauritius, from a Pteridophyte, S.P.B. Madhu (holotype CBS H-23658, culture ex-type CBS 101249 = IMI 296138). Switzerland, from Aphelandra sp., unknown date, P. Petrini, CBS 372.93; idem., CBS 373.93.

Notes: The four isolates included in this species were previously identified as Gliocladium cibotii (CBS 823.73) and Verticillium sp. (CBS 372.93, CBS 373.93 and CBS 101249). The tropical strains CBS 823.73 and CBS 101249 were isolated from fern, while the European ones (CBS 372.93 and CBS 373.93) come from a flowering plant in the family Acanthaceae, which is native to tropical regions of the Americas.

Morphologically, B. macroclavatum resembles B. nepalense in conidial morphology and in the production of chlamydospores in short chains along with pigmented ropes of hyphae. However, in B. macroclavatum the conidia are longer (4–5.2 μm vs. 3.2–4.7 μm), and the chamydospores are larger (4.6–10 × 3.3–6 μm vs. 4.4–5 × 3.5–3.6 μm) than those of B. nepalense.