Phytopathogenic Dothideomycetes - CBS - KNAW

Sizing up Septoria
Fig. 56. Pseudoseptoria obscura (CBS 135103). A, B. Colony sporulating in culture. C. Chlamydospore-like cells developing. D, E. Conidiogenous cells. F–H. Conidia. Scale
bars: B = 250 µm, all others = 10 µm.
in a mucilaginous matrix. Conidiogenous cells subcylindrical to
ampulliform, hyaline, smooth to pale brown, finely verruculose,
18–35 × 3.5–8 µm; apical region with numerous conspicuous
percurrent proliferations, with long, prominent collarettes that
completely enclose and extend above young, developing conidia,
but disintegrating into a mucoid mass with age. Conidia fusiform,
lunate, curved, aseptate, hyaline, smooth, tapering to an subobtuse
to spathulate apex, base truncate (1 µm diam), with a single,
unbranched, eccentric basal appendage, 2–4 µm long; conidia
(from apex to hilum) (24–)26–28(–30) × (2.5–)3 µm.
Culture characteristics: Colonies on PDA flat, round with feathery
margins, lacking aerial mycelium, surface olivaceous-black to rosybuff
for younger tissue, reverse olivaceous-black, to rosy-buff for
younger tissue, after 14 d 1.5 cm diam; on MEA surface olivaceousblack
to buff for younger tissue, reverse olivaceous-black to brick
for younger tissue, after 14 d, 2 cm diam; on OA similar to MEA.
Specimen examined: Iran, Golestan Province, on leaves of Bamboo (Poaceae), 12
May 2009, A. Mirzadi Gohari (holotype CBS H-21302, culture ex-type CBS 135104
= CPC 18119).
Pseudoseptoria obscura Quaedvlieg, Verkley & Crous, sp.
nov. MycoBank MB804434. Fig. 56.
Etymology: Named after the obscure basal appendage that occurs
on some conidia.
On sterile Carex leaves on WA. Conidiomata immersed to
erumpent, globose, dark brown, up to 250 µm diam (smaller than in
18119), unilocular, opening via central ostiole; wall of 3–6 layers of
brown textura angularis. Conidiophores reduced to conidiogenous
cells. Conidiogenous cells subcylindrical to doliiform, hyaline,
smooth to pale brown, finely verruculose, 6–12 × 2–5 µm; apical
region with numerous inconspicuous to conspicuous percurrent
proliferations; collarettes absent to prominent. Conidia fusiform,
lunate, curved, aseptate, hyaline, smooth, tapering to an subobtuse
apex; base truncate, rarely with a single, unbranched, eccentric
basal appendage, 1–2 µm long; conidia (from apex to hilum) (8–)
12–14(–15) × (2–)2.5(–3) µm.
Culture characteristics: Colonies on PDA flat, undulate with
feathery margins, lacking aerial mycelium, surface concentric rings
of fuscous-black to pale purplish grey to fuscous-black, reverse
concentric rings of greyish-sepia to fawn to fuscous-black, after 14
d, 2 cm diam; on MEA similar to PDA; OA flat, undulate, lacking
aerial mycelium, surface fuscous-black to purplish grey for the
younger tissue, reverse greyish-sepia to vinaceous-buff for the
younger tissue.
Specimen examined: Iran, Golestan Province, on leaves of Bamboo (Poaceae), 12
May 2009, A. Mirzadi Gohari (holotype CBS H-21303, culture ex-type CBS 135103
= CPC 18118).
Notes: Species of the genus Aphanofalx occur on members of
Poaceae, presumably as saprobes. The genus is characterised
by having taxa with pycnidial conidiomata, and percurrently
proliferating conidiogenous cells, and hyaline, aseptate conidia
with a basal, excentric appendage. In contrast, species of
Pseudoseptoria are known to occur on members of Poaceae
as plant pathogens. The genus is also characterised by having
taxa with pycnidial conidiomata, and percurrently proliferating
conidiogenous cells, and hyaline, aseptate conidia that lack basal
appendages. During this study we also investigated three strains
identified as P. donasis (CBS 291.69, 313.68 and 417.51), the
type species of Pseudoseptoria. Much to our surprise they formed
a monophyletic lineage (results not shown) with the two strains
described here (which have basal appendages), suggesting that
Pseudoseptoria represents an older name for Aphanofalx, and that
the basal appendage is a species-specific character, as also found
in other groups of coelomycetes (Crous et al. 2012b).
Aphanofalx is presently known from two species, A. mali (conidia
26–33 × 2–2.5 µm), and A. irregularis (conidia 12–28(–31) × (2–)2.5–
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