Highlights of the Didymellaceae - Studies in Mycology

AveSkAMp et al.
Fig. 9. Boeremia exigua var. gilvescens (CBS 101150). A–C. Fourteen-day-old colonies on OA (A), MEA (B) and CHA (C). D. Pycnidia. E. Chains of wollen cells. F. Conidia.
Scale bars: D = 100 μm; E = 100 μm; F = 10 μm.
Culture characteristics: Colonies on OA 75–80 mm diam after
7 d, margin regular or irregular. Immersed mycelium sparsely
visible due to coverage by the aerial mycelium, hyaline or black
to greenish olivaceous, with many pycnidia; reverse mouse-grey
to olivaceous. Colonies on MEA 70–75 mm diam after 7 d, margin
regular or irregular. Immersed mycelium completely covered by a
compact aerial mat, which is smoke-grey with some mouse-grey
zones; reverse black. Colonies on CHA at least (75–)80 mm diam
after 7 d, but often the agar surface is completely covered, margin
regular or somewhat crenate. Immersed mycelium completely
covered by a compact smoke-grey mat of aerial mycelium, or, in
some zones floccose, olivaceous with white tufts; reverse shows
a dendritic leaden-black zone around the colony centre, with black
zones near the colony border. Application of NaOH did not have
any effect.
Pycnidial and conidial shapes and sizes fit within the Ph. exigua
species concept. Conidial matrix yellowish or pale luteous. Brown
pigmented swollen cells occur in chains in the agar and in the aerial
mycelium, measuring (11.5–)12.5–27.5(–31) × (5.5–)7.5–14.5(–18)
μm.
Specimens examined: Philippines, from Solanum tuberosum,1990, L.J.
Turkensteen, CBS 101156 = PD 90/731; The Netherlands; from a graft of Ulmus,
1961, H.M. Heybroek, CBS 373.61; Baarn, from leaves of Dactylis purpurea, 1970,
H.A. van der Aa, holotype designated here CBS H-16281, culture ex-holotype
CBS 761.70; Lisse, from Dahlia, 1982, J. de Gruyter, CBS 101151 = PD 82/1022.
Notes: This novel variety of B. exigua, distinguished from other B.
exigua varieties on basis of DAF analysis (Aveskamp et al. 2009b),
is closely related to B. exigua var. exigua, but different in the colour
of its conidial matrix (yellowish) and absence of a positive reaction to
38
NaOH. This variety may be identical to Ph. exigua var. inoxydabilis
Boerema & Vegh, but as the type culture has been lost (Van der
Aa et al. 2000) a proper comparison of the varieties cannot be
made. Additionally, Ph. exigua var. inoxydabilis was originally only
known from periwinkle (Vinca minor, Vegh et al. 1974), whereas
the strains associated to the present taxon are isolated from a wide
range of host plants.
Boeremia exigua var. heteromorpha (Schulzer & Sacc.)
Aveskamp, Gruyter & Verkley, comb. nov. MycoBank
MB515627.
Basionym: Phoma heteromorpha Schulzer & Sacc., Hedwigia 23:
107. 1884.
≡ Phoma exigua var. heteromorpha (Schulzer & Sacc.) Noordel. &
Boerema, Verslagen Meded. Plziektenk. Dienst Wageningen 166:
109.1989.
Specimens examined: France, Antibes, from Nerium oleander, 1979, CBS 101196
= PD 79/176. Italy, Perugia, from Nerium oleander, 1994, A. Zazzerini, CBS 443.94.
Boeremia exigua var. lilacis (Sacc.) Aveskamp, Gruyter &
Verkley, comb. nov. MycoBank MB515628.
Basionym: Phoma herbarum f. lilacis Sacc., Michelia 2(1): 93. 1880.
Specimen examined: The Netherlands, Wageningen, from a twig of Syringa
vulgaris, June 1976, G.H. Boerema, CBS H-163131, culture CBS 569.79 = PD
72/741.
Notes: Although in the present study this variety clusters outside
the B. exigua cluster, it is phylogenetic affiliation is ambiguous. In
previous studies in which fingerprint markers and actin sequences
were applied to delineate this species complex (Abeln et al.