Crous & Quaedvl., Persoonia 26: 153. 2011. Fig. 54.
Classification: Sordariomycetes, Sordariomycetidae, Magnaporthales, Pyriculariaceae.
Type species: Utrechtiana roumeguerei (Cavara) Videira & Crous, basionym: Scolicotrichum roumeguerei Cavara = Utrechtiana cibiessia Crous & Quaedvlieg. Holotype and ex-type strain of Utrechtiana cibiessia: CBS H-20594, CBS 128780.
DNA barcodes (genus): LSU, ITS.
|Species||Isolates1||GenBank accession numbers2||References|
|Utrechtiana arundinacea||CPC 33994ET||MG934461||MG934468||MG934542||MG934473||Present study|
|U. roumeguerei||CBS 128780T||JF951153||KM485163||KM485232||KM485047||Crous et al., 2011a, Klaubauf et al., 2014|
CBS: Westerdijk Fungal Biodiversity Institute, Utrecht, the Netherlands; CPC: Personal collection of Pedro Crous housed at the Westerdijk Fungal Biodiversity Institute. T and ET indicate ex-type and ex-epitype strains, respectively.
ITS: internal transcribed spacers and intervening 5.8S nrDNA; act: partial actin gene; cal: partial calmodulin gene; rpb1: partial RNA polymerase II largest subunit gene.
Mycelium internal, consisting of septate, smooth, hyaline, branched hyphae. Conidiophores predominantly solitary, erect, straight to flexuous, unbranched, 1-septate, medium brown to dark brown, subcylindrical with swollen basal cell. Conidiogenous cells integrated, terminal, cylindrical or subcylindrical, smooth or finely verruculose, thick-walled with thin-walled, clavate, bluntly rounded apex, with truncate, flattened scar, holoblastic; conidiophores rejuvenating percurrently. Conidia solitary, obpyriform or ellipsoid, pale brown, guttulate to granular, finely verruculose, 1–2-septate, thin-walled, apex bluntly to acutely rounded, base obtusely rounded with a flattened, darkened and thickened hilum that has a central pore. Synasexual morph selenosporella-like present or absent. Microconidiophores arranged in rosettes, branched, septate, pale brown, smooth, subcylindrical. Microconidiogenous cells pale brown, smooth to finely roughened, phialidic, terminal and lateral, fusoid-ellipsoid to ampulliform. Microconidia hyaline, smooth, aseptate, subcylindrical, straight to curved, ends obtuse.
Culture characteristics: Colonies flat, spreading, with moderate aerial mycelium and even smooth margins. On MEA surface dirty white, sometimes turning grey olivaceous when fertile; reverse luteous or olivaceous grey in centre and luteous in outer region. On OA olivaceous grey to iron-grey or dirty white.
Optimal media and cultivation conditions: On OA at 25 °C under dark, or autoclaved barley seeds placed on SNA at 25 °C under near-ultraviolet light (12 h light, 12 h dark).
Distribution: America, Asia, Australia and Europe.
Hosts: Phragmites spp (Poaceae).
Disease symptoms: Leaf spot.
Notes: The genus Utrechtiana was described by Crous et al. (2011a) to accommodate the type species named Utrecthiana cibiessia, which is a foliar pathogen of Phragmites. However, this genus was considered synonymous with Deightoniella by Seifert et al. (2011) because of the morphology of the conidiophores (solitary, brown, with percurrent rejuvenation) and conidia (brown and septate). Moreover, U. cibiessia was demonstrated to be a synonym of Deightoniella roumeguerei, which Klaubauf et al. (2014) showed to belong to Pyriculariaceae, a family containing numerous cryptic fungal genera on Poaceae.
However, Deightoniella has been shown to represent a polyphyletic genus. For example, Deightoniella torulosa, which is a foliar pathogen of Musa, proved to be a species of Corynespora (Crous et al. 2013), while a similar fungus occurring on leaf spots of Phragmites in South Africa was placed in Neodeightoniella (Crous et al. 2013). In a recent study, Videira et al. (2017) considered Utrechtiana and Deightoniella based on the type species Deightoniella africana to be different genera based on morphological characteristics. Utrechtiana lacks torsive to flexuous conidiophores with prominent conidiophore swellings, and its conidia are also pale brown, smooth to finely roughened, with prominent thickened, darkened scars. In contrast, conidia in Deightoniella are medium brown, verruculose, and obpyriform with prominent apical taper. In order to clarify the phylogenetic relationships between both genera, fresh material of Deightoniella africana is needed.
Utrechtiana arundinacea (Corda) Crous, Quaedvl. & Y. Marín, comb. nov. MycoBank MB824141. Fig. 54.
Basionym: Helminthosporium arundinaceum Corda, as “Helmisporium”, Icon. fung. (Prague) 3: 10, tab. 2, fig. 25. 1839.
Synonyms: Napicladium arundinaceum (Corda) Sacc., Syll. fung. 4: 482. 1886.
Deightoniella arundinacea (Corda) S. Hughes, Mycol. Pap. 48: 29. 1952.
Causing blight-like amphigenous lesions along leaves of Phragmites, medium brown with red-purple margins and yellow halo, extending across breadth of leaf, up to 7 mm diam, and along length, up to 20 cm long. Macroconidiophores 30–50 × 9–12 μm, amphigenous, predominantly solitary, but at times in fascicles of up to three, straight to flexuous, unbranched, 1-septate, medium brown, smooth, subcylindrical with swollen basal cell, 10–15 μm diam. Macroconidiogenous cells 20–35 × 7–9 μm, integrated, terminal, cylindrical, thick-walled with thin-walled apex, holoblastic; conidiophores proliferate percurrently. Macroconidia (22–)37–42(–45) × (17–)19–20(–21) μm, solitary, obpyriform, pale brown, guttulate, finely verruculose, (1–)2-septate, with distinct dark brown hilum, 3–4 μm. A selenosporella-like synasexual morph develops in culture, with microconidiophores arranged in rosettes, 15–40 × 3–6 μm, branched, 3–6-septate, pale brown, smooth, subcylindrical. Microconidiogenous cells 5–14 × 3–4 μm, pale brown, smooth to finely roughened, phialidic, terminal and lateral, fusoid-ellipsoid to ampulliform. Microconidia 7–10 × 1.5–2 μm, hyaline, smooth, aseptate, subcylindrical, straight to curved, ends obtuse. Macroconidiophores in culture up to 6-septate, 100 μm tall. Macroconidia 23–50 × 11–15 μm, slender, pyriform, prominently verrucose, medium brown.
Culture characteristics: Colonies flat, spreading, with moderate aerial mycelium and even smooth margins. On MEA surface dirty white; reverse olivaceous grey in centre, luteous in outer region. On OA olivaceous grey to iron-grey.
Materials examined: Czech Republic, Prague, on living leaves of Phragmites sp. (Poaceae), 1838 (holotype in PRM missing, but slide ex-holotype, DAOM 19793). The Netherlands, on leaves of Phragmites sp. (Poaceae), 2 Jun. 2017, A. Mulder (epitype of Helminthosporium arundinaceum designated here CBS H-23402, MBT380884, culture ex-epitype CPC 33994).
Notes: Utrechtiana arundinacea is a commonly encountered European taxon treated in Deightoniella in previous studies (Constantinescu, 1983, Mel'nik and Shabunin, 2011, Ghosta and Abrinbana, 2016). Morphologically, U. arundinacea and U. constantinescui appear to be related.
Macroconidia of U. arundinaceum exhibit a strange phenomenon where a third septum develops 3–5 μm from the apex. The conidium body is prominently guttulate, except for this terminal chamber, which is smooth, pale brown, and lacks any guttules. This strange conidial apex is also visible in conidia of U. constantinescui (Mel’nik & Shabunin 2011), and apparently plays some role in infection/attachment, probably exuding a mucoid droplet, as is also seen in some genera in the Pyriculariaceae (Klaubauf et al. 2014). Furthermore, Mel’nik & Shabunin (2011) illustrate a selenosporella-like synasexual morph in both species, which has not been seen in U. roumeguerei, the type species of the genus.
Utrechtiana roumeguerei was considered conspecific with U. arundinacea (Ellis 1957) until Constantinescu (1983) demonstrated that they are distinct species based on morphology and pathogenicity. Utrechtiana arundinacea often produces percurrently proliferating conidiogenous cells and obclavate 2-septate conidia, while U. roumeguerei is characterised by rarely percurrent conidiogenous cells and ovate to broadly ellipsoidal, 1-septate conidia. Moreover, U. arundinacea produces systemic infection in the host issues, whereas U. roumeguerei induces a local infection with limited development. In the present study, the DNA data support the placement of both taxa in the same genus (Fig. 28).
The holotype specimen of Helminthosporium arundinaceum could not be located in PRM, and is presumed missing. However, a slide from the original material was preserved in DAOM. Due to the lack of living culture of that species, a specimen isolated from the same host and region is here designated as epitype.
(Melnik & Shabunin) Crous & Y. Marín, comb. nov. MycoBank MB824142.
Basionym: Deightoniella constantinescui Melnik & Shabunin, Mikol. Fitopatol. 45: 257. 2011.
Notes: The new combination U. constantinescui is designated here based on the morphology of its macro- and microconidial morphs. Fresh material should be recollected to verify this placement. As we mentioned above, this species is morphologically related to U. arundinacea. Both species can be distinguished based on the shape of their macroconidia (obpyriform in U. arundinacea vs. barrel-shaped in U. constantinescui) and the position of the conidial septa in U. constantinescui, 7–13 μm apart.
Authors: Y. Marin-Felix, W. Quaedvlieg & P.W. Crous