Didymella michaelii sp. nov., a new pathogen on Impatiens parviflora DC.
Didymella michaelii sp. nov., ein neues Pathogen an Impatiens parviflora DC.
Journal für Kulturpflanzen, 68 (7). S. 208–210, 2016, ISSN 1867-0911, DOI: 10.5073/JfK.2016.07.03, Verlag Eugen Ulmer KG, Stuttgart
Didymella michaelii sp. nov., a new species collected on Impatiens parviflora DC., differs from other species of Didymella on this host in the diameter of the pycnidia and in length and width of the conidia.
Key words: Didymella michaelii sp. nov., Impatiens parviflora, symptoms, systematics, new species
Didymella michaelii sp. nov., eine neue Art an Impatiens parviflora DC., unterscheidet sich von anderen Arten der Gattung Didymella auf diesem Wirt im Durchmesser der Pyknidien und in Länge und Breite der Konidien.
Stichwörter: Didymella michaelii sp. nov., Impatiens parviflora, Symptome, Systematik, neue Art
On Impatiens parviflora we know three different species of the asexual state of Didymella, as there are Ascochyta impatientis Bres., A. weissiana Allesch., and A. phaseolorum Sacc. On leaves of Impatiens parviflora originating from the littoral zone under trees of a windbreak of the rivulet Lafnitz at Eltendorf in Burgenland an asexual state of Didymella was identified which differs in the diameter of the pycnidia, length and width of conidia to the well-known species on Impatiens parviflora (Table 1).
Table 1. On Impatiens spp. up to now described species of Ascochyta (in chronological order) according to the original descriptions
Species | Host | Synonyms and remarks | Diameter of pycnidia | Length of conidia | Width of conidia | Characteristics of the |
Ascochyta phaseolorum Sacc. | Phaseolus vulgaris | Current name: Boeremia exigua (Desm.) Aveskamp, Gruyter and Verkley (2010) | 100 | 10 | 3 | Hyaline, oblong, rounded at both ends, |
Ascochyta impatientis Bres. | Impatiens parviflora | Diplodina impatientis Bubák and Kabát (1912) | 160–200 | 8–11 | 3–4 | Hyaline, mostly elliptical, only 1-septate. |
Ascochyta weissiana Allesch. (Allescher, 1901) | Impatiens balsamina | 10–16 | 3–4.5 | Hyaline, oblong, rounded at both ends, | ||
1) according to the description in Mel’nik (2000) | ||||||
For the determination of the fungus the usual mycological routine methods of light microscopy were adopted. Pycinidia and conidia of the fungus were stained with Wittmann’s Blue (Wittmann, 1970). Both have been measured using the programme labSens by Olympus.
The conidia of the new species differ in length and width from the above mentioned three species. The diameter of the pycnidia of the new species varies from 75.75–158.72 μm with an average of 101 μm. The ostioles measure 9.73–24.97 μm (average 16.31 μm). The conidia are 6.2–10.2 μm long (average 8.11 μm) and 1.58–3.04 μm wide (average 2.31 μm) and show one septum in the midth of the conidia.
Infected leaves dropped down and later in the year no further infections could be observed.
Didymella michaelii Bedlan sp. nov.
Index Fungorum IF552247
On leaves greyish, roundish or sometimes irregular shaped spots which are dark brown to purple-brown surrounded (Fig. 1). Conidiomata (pycnidia) on the upper side of the leaf spots (Fig. 2). Pycnidia semi-immersed, brown, globose, 75.75–158.72 μm diameter (average 101 μm). The ostioles measure 9.73–24.97 μm (average 16.31 μm). The conidia are hyaline, oblong-cylindrical, rounded at the ends, sometimes bent, 6.2–10.2 μm long with an average of 8.11 μm and 1.58–3.04 μm wide with an average of 2.31 μm and 1 septum in the midth (young conidia aseptate) and few are 2-septate, biguttulate. At the septum sometimes scarcely constricted (Fig. 3).
Fig. 1. Symptoms on upper side of leaf.
Fig. 2. Leaf spot.
Fig. 3. Pycnidia and conidia (stained with Wittmann’s Blue).
On living leaves of Impatiens parviflora DC.
Type: Austria, Eltendorf (Burgenland, district of Jennersdorf), under trees of a windbreak in the littoral zone of the rivulet Lafnitz (N 46° 59.929’, O 16° 12.152’). On living leaves of Impatiens parviflora DC., 12 June 2015, leg. et det. G. Bedlan (holotype, hb W).
The type specimen has been deposited at the department of Botany, Natural History Museum, Vienna (hb W).
Allescher, A., 1901: In: Rabenhorst’s Kryptogamenflora von Deutschland. VI. Abtheilung: Fungi imperfecti: Hyalinsporige Sphaerioideen, p. 647.
Aveskamp, M.M., J. Gruyter de, J.H.C. Woudenberg, G.J.M. Verkley, P.W. Crous, 2010: Highlights of the Didymellaceae: A polyphasic approach to characterise Phoma and related pleosporalean genera. Studies in Mycology 65, p. 37.
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Mel‘nik, V.A., 2000: Key to the fungi of the genus Ascochyta Lib. (Coelomycetes). Mitt. Biol. Bundesanst. Land-Forstwirtsch., Berlin-Dahlem, Heft 379, 192 S.
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Wittmann, W., 1970: Ein neues Rezept zur Herstellung mykologischer Präparate. PflSchber., Bd. 41, Heft 5/6/7, p. 91-94.
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