Colletotrichum: complex species or species ... - CBS - KNAW

Damm et al.
description is reminiscent of the C. acutatum species complex, but
cultures are not available, we have not seen type material, and the
species was described from a different continent.
There is a number of Gloeosporium species that were described
on Eucalyptus spp. in different countries, but none was described
in Asia, and most differ considerably from C. indonesiense.
Gloeosporium eucalypti was described on E. corynocalyx in
Australia, and forms shorter conidia than C. indonesiense,
measuring 8–10 × 3–4 µm (Saccardo 1906) compared to those
of C. indonesiense that average 12.3 × 3.8 µm and 15.4 × 3.7
µm on SNA and Anthriscus stem, respectively. Gloeosporium
eucalyptorum, described on leaves and twigs of Eucalyptus spp.
in Italy, has larger conidia, measuring 18–26 × 5–6 µm. They have
a different shape, cylindrical to cylindric-clavate, straight to slightly
curved, with both ends obtuse (see Tavola VIII, fig. 5 in Turconi
1924), while conidia of C. indonesiense are straight and cylindrical,
with one acute end when formed on SNA and both ends acute
when formed on Anthriscus stem. Gloeosporium capsularum was
described on Eucalyptus sp. in California, USA; it has longer and
narrower conidia, measuring 18–20 × 2.5 µm. They are straight
and cylindrical with both sides obtuse (Saccardo 1884). Conidia of
Gm. nigricans described from leaves of E. pauciflora in Australia
are ovoid and wider than those of C. indonesiense, measuring 12
× 7 µm (Cooke 1891). Gloeosporium ochrostictum from E. rostrata
in Australia has oblong-clavate, inaequilateral conidia measuring
9–12 × 4–5 µm (Saccardo 1899); conidia of C. indonesiense
are narrower and aequilateral. We have not examined authentic
material of any of these taxa, but bearing in mind that none have
associated cultures and that type material would be too old to yield
multigene sequences, we prefer to leave them in obscurity.
There are Colletotrichum species in the C. boninense species
complex known on Eucalyptus: C. boninense and C. karstii have
both been found on Eucalyptus in South Africa, and C. karstii also
occurs on the related host genus Eugenia in Brazil (Damm et al.
2012, this issue).
Colletotrichum indonesiense is separated from other species
by TUB2, ACT, GAPDH and CHS-1 sequences, and most
effectively with TUB2. With CHS-1 there is only one bp difference
from C. laticiphilum, and the HIS3 sequence is the same as that of
that species. The closest match in a blastn search with the TUB2
sequence of strain CBS 127551 with 99 % identity (6 differences)
was GU246633 from isolate R14 from Capsicum annuum from
South Korea (Sang et al. 2011; identified by us as C. scovillei).
The closest match with the GAPDH sequence (with 97 % identity, 7
bp differences) is isolate OCC95 from an unspecified crop in India
(HQ846719; P. Chowdappa, C.S. Chethana, S. Madhura, unpubl.
data). There are more than 40 ITS sequences in GenBank with
99 % identity (1 bp difference) to the ITS sequence of C.
indonesiense.
Colletotrichum johnstonii Damm, P.F. Cannon & Crous,
sp. nov. MycoBank MB800503. Fig. 14.
Etymology: Named after Peter R. Johnston (Landcare Research),
a major contributor to recent improvements in Colletotrichum
systematics.
Sexual morph not observed. Asexual morph on SNA. Vegetative
hyphae 1–7 µm diam, hyaline, smooth-walled, septate, branched.
Chlamydospores not observed. Conidiomata not developed,
conidiophores formed directly on hyphae. Setae not observed in
type, but present in strain IMI 357027, medium brown, basal cell
sometimes pale brown, smooth-walled, 0–1-septate, 35–55 µm
long, base cylindric-conical, often constricted at septum, 3.5–4
µm diam, the tip ± acute. Conidiophores hyaline, smooth-walled,
septate, branched. Conidiogenous cells hyaline smooth-walled,
cylindrical, sometimes slightly inflated, sometimes lacking a basal
septum and continuous with the conidiophore, some polyphialides
observed, discrete phialides measure 6–27 × 2.5–4 µm, opening
1–2 µm diam, collarette 1–1.5 µm long, periclinal thickening distinct.
Conidia hyaline, smooth-walled, aseptate, straight, cylindrical to
fusiform with one end slightly acute and one end round or slightly
acute, (13.5–)14.5–19(–21.5) × (3.5–)4.5–5(–6) µm, mean ± SD
= 16.7 ± 2.1 × 4.7 ± 0.4 µm, L/W ratio = 3.6. Appressoria sparse,
single or in loose groups, pale to medium brown, smooth-walled,
elliptical to clavate or irregular, the outline undulate or entire, (6–)
8–11.5(–14) × (2–)4–7.5(–10.5) µm, mean ± SD = 9.6 ± 1.7 × 5.8
± 1.9 µm, L/W ratio = 1.7.
Asexual morph on Anthriscus stem. Conidiomata acervular,
conidiophores formed on pale brown, angular, basal cells, 3.5–7.5
µm diam. Setae not observed in type, but present in strain IMI
357027, medium brown, basal cell pale brown, smooth-walled,
0–1-septate, 40–60 µm long, base cylindric-conical to slightly
inflated, 2.5–5 µm diam, the tip ± acute to ± roundish, sometimes
with a constriction. Conidiophores hyaline, smooth-walled, septate,
branched, to 60 µm long. Conidiogenous cells hyaline, smoothwalled,
cylindrical, 11–26 × 2.5–4 µm, opening 1–2 µm diam,
collarette 1 µm long, periclinal thickening distinct. Conidia hyaline,
smooth-walled, aseptate, straight, cylindrical to fusiform with one
end slightly acute and one end round or slightly acute, (14.5–)15.5–
17(–18) × 4.5–5(–5.5) µm, mean ± SD = 16.3 ± 1.0 × 4.9 ± 0.3 µm,
L/W ratio = 3.3.
Culture characteristics: Colonies on SNA flat with entire margin,
hyaline; medium, filter paper and Anthriscus stem partly covered
with thin floccose white to pale grey aerial mycelium and orange
acervuli, reverse hyaline with orange to grey acervuli shining
through; growth rate 23–24.5 mm in 7 d (36–37 mm in 10 d).
Colonies on OA flat to raised, with entire margin; surface covered
with floccose whitish to pale olivaceous grey aerial mycelium and
orange acervuli, reverse rosy buff, olivaceous grey to iron-grey in
the centre; growth rate 22.5–24.5 mm in 7 d (37.5–39 mm in 10 d).
Conidia in mass orange.
Material examined: New Zealand, AK, Auckland, from fruit rot of Solanum
lycopersicum, 29 Feb. 1990, J.M. Dingley, (CBS H-20809 holotype, culture ex-type
CBS 128532 = ICMP 12926 = PRJ 1139.3); Takaka, from fruit rot of Citrus sp., 1989,
collector unknown (deposited in IMI 1993 by P.R. Johnston, No. 1125.5), culture IMI
357027 = PRJ 1125.5.
Notes: Colletotrichum johnstonii is part of clade 4 but has slightly
longer conidia than those of C. godetiae, and can be separated
from other species on the basis of ACT, HIS3, TUB2, and GAPDH
sequences. The gene that performs best as a differential test is
ACT. The GAPDH sequence is only 1 bp different from that of
C. godetiae, while the CHS-1 sequences of both species are the
same. The two C. johnstonii strains from citrus and tomato and a
strain from pear that is newly described here as C. pyricola were
included in C. acutatum group C by Lardner et al. (1999). Two of
their tamarillo strains, also in Lardner’s group C, had near-identical
RAPD banding patterns to that of the ex-type strain of C. johnstonii.
There are two strains from citrus (PJ50 = PRJ 1125.5 and PJ49 =
PRJ 1124.5) and one from tamarillo (Pj18 = PRJ 979.9) from New
Zealand included in the study of Guerber et al. (2003) that have the
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