Highlights of the Didymellaceae - Studies in Mycology

Phoma polemonii Cooke, Grevillea 13(68): 94. 1885.
Specimen examined: The Netherlands, from Polemonium caeruleum, 1983, J. de
Gruyter, CBS 109181 = PD 83/757.
Phoma xanthina Sacc., Michelia 1(4): 359. 1884.
Specimens examined: The Netherlands, Baarn, from leaves of Delphinium sp.,
May 1968, H.A. van der Aa, CBS H-8938, culture CBS 383.68; from Delphinium sp.,
1984, G.H. Boerema, PD 84/407.
Group C:
The species in Group C cluster in two subgroups: One comprising
the Clematis pathogens Ph. clematidina and Coniothyrium
clematidis-rectae, the other subgroup comprising Ph.
aquilegiicola and Ph. glaucii, two pathogens of Ranunculaceae
and Papaveraceae, respectively. All three Phoma species in this
group were morphologically linked to the section Heterospora
(Boerema et al. 1997), but are distinct from the species in clade
S by the absence of conidia that represent the Stagonosporopsis
synanamorph in culture, although smaller septate conidia do occur.
In these species the Stagonosporopsis synanamorph is only known
from in vivo material (Boerema 1993, Boerema et al. 1997).
The several species that were associated with the Ph.
clematidina morphotype have recently been distinguished in a study
of Woudenberg et al. (2009). In the same study, the authors showed
that C. clematidis-rectae is closely related and, based on sequence
analysis, a member of the family Didymellaceae. The major
character on which this species is regarded as distinct from Ph.
clematidina is by the production of pale brown pigmented conidia.
In addition, the conidiogenesis of Coniothyrium is annellidic with
percurrent proliferation, in contrast to the conidiogenesis in Phoma,
which is considered to be solely phialidic with periclinal thickening
(Boerema & Bollen 1975, Sutton 1980). Evidence for the presence
of annellides has, however, not been observed in C. clematidisrectae,
while conidial pigmentation is relatively pale in comparison
to other Coniothyrium species. Pigmented conidia have also been
observed in various Phoma species before (Dorenbosch 1970,
Boerema et al. 2004, Aveskamp et al. 2009a). These features may
indicate that this species is actually a Phoma with early conidial
pigmentation. Therefore C. clematidis-rectae is recombined into
Phoma below.
Phoma aquilegiicola M. Petrov, Acta Inst. Bot. Acad. Sci.
USSR Pl. Crypt. [Trudy Bot. Inst. Akad. Nauk SSSR] Fasc.
1: 281. 1933.
Specimens examined: The Netherlands, from a stem of Aconitum pyramidale,
1973, G.H. Boerema, CBS 107.96 = PD 73/598; from a stem of Aquilegia sp., 1979,
G.H. Boerema, CBS 108.96 = PD 79/611.
Phoma clematidina (Thüm.) Boerema, Verslagen Meded.
Plziektenk. Dienst Wageningen (Jaarboek 1978) 153: 17.
1979. emend. Woudenberg et al., Persoonia 22: 59. 2009.
Basionym: Ascochyta clematidina Thüm., Bull. Soc. Imp.
Naturalistes Moscou 55: 98. 1880.
Specimens examined: Russia, Minussinsk, from leaves of Clematis glaucae,
N. Martianoff, isotype LE 40082; The Netherlands, Spaubeek, from the stem
of Clematis sp., July 1978, G.H. Boerema, epitype CBS H-16193, culture exepitype
CBS 108.79 = PD 78/522; from Clematis sp., I. de Boer, Nov. 1949, CBS
201.49; Boskoop, from Clematis jackmanii, C. Dorsman, Oct. 1962, CBS 195.64;
Wageningen, from Selaginella sp. M.M.J. Dorenbosch, 1966, CBS 520.66; U.K.,
England, from Clematis sp., Jan. 1966, F.T. Last, CBS 102.66.
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Phoma And relAted pleoSporAleAn generA
Phoma clematidis-rectae (Petr.) Aveskamp, Woudenberg &
Gruyter, comb. nov. MycoBank MB515592.
Basionym: Coniothyrium clematidis-rectae Petr., Fungi Polon. 576.
1921.
Pycnidia solitary or confluent, immersed or produced on the agar
surface, globose, glabrous, (80–)85–130(–155) μm diam, in older
cultures pycnidia may become larger and grow after maturation
to 220–250 μm diam. Ostioles 1(–4), wide, non-papillate to
papillate or, in older cultures, on a elongated neck. Pycnidial wall
pseudoparenchymatous, composed of oblong to isodiametric
cells, 4–5 layers, (10–)11–19(–19.5) μm thick, outer 1–2 layers
pigmented. Conidiogenous cells phialidic, hyaline, simple, smooth,
ampulliform to doliiform, measuring 3–4.5(–5) × 2.5–4.5 μm.
Conidia ellipsoidal to cylindrical, thin-walled, smooth, aseptate, (3–)
4–7(–8) × 2–3(–3.5) μm, with (2–)5–12 guttules, initially hyaline,
but mature conidia become slightly brownish pigmented. Conidial
matrix sepia.
Culture characteristics: Colonies on OA 42–52 mm diam after 7
d, margin regular. Immersed mycelium dark brick to sepia or irongrey,
but hyaline near the colony margin. Pycnidia in concentric
rings give the colony an olivaceous tinge. Aerial mycelium absent;
reverse concolourous. Colonies on MEA 27–52 mm diam after 7
d, margin regular. Aerial mycelium incidentally occurs in sectors in
some strains, grey to olivaceous. Immersed mycelium rosy-buff to
rosy-vinaceous with olivaceous and grey tinges; reverse olivaceous
iron-grey to saffron. Application of NaOH did not have any effect.
Specimens examined: The Netherlands, Boskoop, from Clematis sp., 1963, G.H.
Boerema, CBS H-20275, culture CBS 507.63 = PD 07/03486747 = MUCL 9574;
from Clematis sp., 1995, J. de Gruyter, PD 95/1958.
Notes: In congruence with the studies of Woudenberg et al. (2009),
this species was found to be closely related to Ph. clematidina and
other Didymellaceae species. In contrast, it is only distantly related
to the type species of Coniothyrium, C. palmarum. Therefore, a
recombination into Phoma is proposed here. The present species
is clearly distinct from Ph. clematidina by the production of
pigmented conidia, although the level of pigmentation is low, which
distinguishes Ph. clematidis-rectae from the species remaining in
Coniothyrium that produce darker, olivaceous conidia.
Phoma glaucii Brunaud, “Ph. glauci”, Ann. Soc. Sci. Nat. La
Rochelle 1892: 97. 1892.
Specimens examined: The Netherlands, near Lisse, from Dicentra sp., 1979, G.H.
Boerema, CBS 112.96; Wageningen, from a leaf of Chelidonium majus, 1994, G.H.
Boerema, CBS 114.96 = PD 94/888.
Groups D & E – Leptosphaerulina and Macroventuria:
The most remarkable findings in the Didymellaceae are the
Leptosphaerulina and Macroventuria (clade E) teleomorph genera.
The species belonging to these teleomorphs are found amidst the
Didymellaceae, causing the genus Didymella to be paraphyletic.
The species in both genera are closely related to each other, as
was already pointed out by Kodsueb et al. (2006), who, however,
missed the link with Didymella. A phomoid anamorph state has, thus
far, not been recorded for any of the species in these teleomorph
genera.
Leptosphaerulina is morphologically distinct from Macroventuria
and Didymella, although all three genera are known for their hyaline
ascospores (Van der Aa 1971, Von Arx 1981). Leptosphaerulina
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