Highlights of the Didymellaceae - Studies in Mycology

Notes: This species was isolated twice from Opuntia on the Canary
Isles. Around the time of the second isolation (CBS 347.82), also
Ph. dimorpha sp. nov. was isolated from the same location and
host substrate. This species is described above. A third species
that is found in association with Opuntia is Ph. opuntiae, which is,
however, rather distinct in morphology and phylogeny.
Phoma medicaginis var. macrospora Boerema, R. Pieters
& Hamers, Netherlands J. Pl. Pathol. 99(Suppl. 1): 19. 1993.
Specimens examined: Canada, Saskatchewan, Saskatoon, from seed of Medicago
sativa, 1965, H.W. Mead, CBS 404.65 = IMI 116999. U.S.A., Minnesota, from
Medicago sativa, Sep. 1953, M.F. Kernkamp, holotype CBS H-16487, ex-holotype
culture CBS 112.53.
Phoma medicaginis var. medicaginis Malbr. & Roum. apud
Roumeguère, Fungi Selecti Galliaei Exs. 37: 3675. 1886.
Specimens examined: Czech Republic, from Medicago sativa, CBS 316.90 = CCM
F-187. Italy, Perugia, from a leaf of Medicago sativa, 1963, M. Ribaldi, CBS H-
16483, culture CBS 479.63. The Netherlands, from a leaf of Medicago sativa, 1966,
M.M.J. Dorenbosch, CBS 533.66 = ATCC 16929 = PD 66/370. Turkey, Ankara, from
Medicago sativa, 1942, S. Kuntay, CBS 107.42. U.S.A., Minnesota, from Medicago
sativa, Sep. 1953, M.F. Kernkamp, CBS 110.53; Minnesota, from Medicago sativa,
Sep. 1953, M.F. Kernkamp, CBS 111.53.
Phoma microchlamydospora Aveskamp & Verkley,
Mycologia 101: 374. 2009.
Specimens examined: U.K., from an unknown vegetable plant, 1990, D. Hyall,
CBS 491.90; from leaves of Eucalyptus sp., 1994, A.M. Ainsworth, holotype CBS
H-20147, ex-holotype culture CBS 105.95.
Phoma nebulosa (Pers.) Berk., Outl. Brit. Fung. (London):
314. 1860.
Basionym: Sphaeria nebulosa Pers., Observ. Mycol. 2: 69. 1799.
Specimens examined: Austria, Kaprun, from a stem of Urtica dioica, Jan. 1975,
G.H. Boerema, CBS H-16510, culture CBS 503.75= ATCC 32163 = DSM 63391 =
IMI 194766 = PD 75/4. The Netherlands, from a stem of Mercurialis perennis, 1983,
CBS 117.93 = PD 83/90.
Phoma negriana Thüm., Die Pilze des Weinstockes, Vienna:
185. 1878. Originally described as "Ph. negrianum".
Specimens examined: Germany, Oberdollendorf am Rhein, from Vitis vinifera, July
1969, L. Kiewnik, CBS H-16511, culture CBS 358.71. The Netherlands, from Vitis
vinifera, 1979, PD 79/74; from Vitis vinifera, 1979, PD 79/75; from Vitis vinifera,
1979, PD 79/76.
Phoma nigripycnidia Boerema, Gruyter & Noordel.,
Persoonia 16(3): 356. 1997.
Specimen examined: Russia, from a leaf of Vicia cracca, 1969, M. Ondrej, holotype
L 992.163.150, ex-holotype culture CBS 116.96 = CCMF 243 = PD 95/7930.
Phoma omnivirens Aveskamp, Verkley & Gruyter, Mycologia
101: 375. 2009.
Specimens examined: Belgium, Gembloux, from Phaseolus vulgaris, 1968, L.
Obando, holotype CBS H-20151, ex-holotype culture CBS 341.86. India, Japalbur,
from an unknown substrate, 1977, D.P. Tiwari, CBS 654.77. Papua New Guinea,
Varirata National Park, from soil, Aug. 1995, A. Aptroot, CBS 991.95. Varirata
National Park. From soil, Aug. 1995, A. Aptroot, CBS 992.95. Tanzania, from
Statice sp., 1990, J. de Gruyter, CBS 123397 = PD 90/1555. The Netherlands,
from Chrysanthemum indicum, 1981, J. de Gruyter, CBS 123396 = PD 81/122.
www.studiesinmycology.org
Phoma And relAted pleoSporAleAn generA
Phoma putaminum Speg., Atti Soc. Crittog. Ital. 3: 66. 1881.
Specimens examined: The Netherlands, from a branch of Ulmus sp., 1975, G.H.
Boerema, CBS 372.91 = PD 75/960. Denmark, from the rhizosphere of Malus
sylvestris, Mar. 1968, E. Sønderhousen, CBS 130.69 = CECT 20054 = IMI 331916.
Phoma rhei (Ellis & Everh.) Aa & Boerema apud De Gruyter,
Boerema & Van der Aa, Persoonia 18 (1): 42. 2002.
Basionym: Ascochyta rhei Ellis & Everh., Proc. Acad. Nat. Sci.
Philadelphia 1893: 160. 1893.
Specimen examined: New Zealand, from a leaf of Rheum rhaponticum, CBS
109177 = LEV 15165 = PD 2000/9941.
Phoma selaginellicola Gruyter, Noordel., Aa & Boerema,
Persoonia 15(3): 399. 1993.
Specimen examined: The Netherlands, from a leaf of Selaginella sp., 1977, G.H.
Boerema, CBS 122.93 = PD 77/1049.
Phoma versabilis Boerema, Loer. & Hamers, Persoonia
16(2): 154. 1996.
Specimens examined: Germany, Westfalen, Oberdresselendorf, from stems
of Cardamine impatiens, Oct. 1925, A. Ludwig, holotype L 995.229.369. The
Netherlands, Wageningen, from a stem of Silene sp., 1982, G.H. Boerema, CBS
876. 97 = PD 82/1008; from Stellaria media, 2000, J. de Gruyter, PD 2000/1379.
DISCUSSION
What is Phoma?
According to the generic concept which is applied today, species of
Phoma are relatively simple coelomycetes that are characterised
by the in vitro production of mainly unicellular, hyaline conidia from
monophialidic, doliiform to flask-shaped conidiogenous cells in
pycnidial conidiomata (Boerema & Bollen 1975).
Many species that currently are accommodated in sections
Paraphoma, Pilosa and Plenodomus are phylogenetically basal to the
Didymellaceae, in which most other Phoma taxa, including the type
species are accommodated. These results support the work of Reddy
et al. (1998), who advocated that the genus Plenodomus should be
reinstalled as a separate genus. Torres et al. (2005b) subsequently
made a novel description in this genus, Pl. morganjonesii. A paper
by De Gruyter et al. is in preparation, in which all species of Phoma
section Plenodomus recognised by Boerema et al. (1994, 1996) and
Boerema & De Gruyter (1999), will be taxonomically revised.
However, in the present study, it has become clear that the
phylogenetic boundaries between Phoma and several closely
related genera that are defined on their conidial characters are
ambiguous. Species that produce consistently two-celled hyaline
conidia classified therefore traditionally in the genus Ascochyta
appear to have evolved independently multiple times during
evolution together with typical Phoma taxa, in several lineages of
the pleosporalean tree (Fig. 1). Also other conidial characters, such
as the pigmentation of spores, as formed by Phoma clematidisrectae
(formerly in Coniothyrium) and Microsphaeropsis olivacea,
appear not to be reliable for the delimitation of the genus Phoma.
Thus, based on the trees presented in this study, it can be concluded
that Phoma, as defined by Saccardo (1880, 1884) and emended by
Boerema & Bollen (1975) is highly polyphyletic.
The close relation of Phoma with Ascochyta has often been
observed before, as strains of both genera are often highly similar
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