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

The Colletotrichum acutatum species complex
Fig. 16. Colletotrichum laticiphilum (from ex-holotype strain CBS 112989). A–B. Conidiomata. C–H. Conidiophores. I–L. Appressoria. M–N. Conidia. A, C–E, M. from Anthriscus
stem. B, F–L, N. from SNA. A–B. DM, C–N. DIC, Scale bars: A = 100 µm, C = 10 µm. Scale bar of A applies to A–B. Scale bar of C applies to C–N.
to pale brown, smooth-walled, ampulliform to cylindrical, 9–15 ×
3.5–5.5 µm, opening 1–1.5 µm diam, collarette 0.5–1 µm long,
periclinal thickening visible. Conidia hyaline, smooth-walled,
aseptate, straight, cylindrical with one end round and one end
slightly acute, (10–)12–15(–19.5) × 4–5(–5.5) µm, mean ± SD =
13.6 ± 1.7 × 4.5 ± 0.3 µm, L/W ratio = 3.0.
Culture characteristics: Colonies on SNA flat with entire margin,
hyaline to pale honey, filter paper pale olivaceous grey; growth
rate 22.5 mm in 7 d (33.5 mm in 10 d). Colonies on OA flat with
entire margin; surface white, buff to pale isabelline, covered with
short felty white aerial mycelium, reverse buff to honey; growth
rate 22.5–23 mm in 7 d (32.5–35 mm in 10 d). Conidia in mass
whitish.
Material examined: India, Kerala, Kottayam, Rubber Research Institute campus,
from raised spots on leaf of Hevea brasiliensis, 1999, unknown collector, (CBS
H-20799 holotype, culture ex-type CBS 112989 = IMI 383015 = STE-U 5303 =
CG 6
). Colombia, Meta, Villavicencio, from leaf, anthracnose of Hevea brasiliensis,
14 Aug. 2010, O. Castro, culture CBS 129827 = CH2.
Notes: Colletotrichum leaf disease (CLD) has been considered to be
a major cause of declining yields of Hevea brasiliensis in Southeast
Asia (Brown & Soepena 1994, Jayasinghe et al. 1997, Saha et al.
2002). The pathogen was at first routinely identified as C. heveae
(Petch 1906) and then assumed to be C. gloeosporioides (s. lat.)
(Carpenter & Stevenson 1954, von Arx 1957).
Jayasinghe and colleagues found that the majority of strains
examined from Sri Lanka belonged to C. acutatum (s. lat.), and
Saha et al. (2002) reported this species from India as well; it is likely
that similar strains are widespread in the region. Saha et al. (2002)
revealed that C. acutatum (s. lat.) causes the raised spot symptom,
while C. gloeosporioides (s. lat.) causes both anthracnose and
papery lesions on Hevea leaves in India. In a study from Sri Lanka,
Thambugala & Deshappriya (2009) found that C. acutatum causes
larger lesions and can act synergistically in combination with C.
gloeosporioides to cause CLD. Strain IMI 383015 is one of the
strains causing the raised spots on Hevea leaves in India. It was
included in the study of Saha et al. (2002) and also in the study of
Lubbe et al. (2004), who generated its ITS and TUB2 sequences.
The TUB2 sequence of strain IMI 383015 (AY376556) was also
included in the TUB2 phylogeny by Shivas & Tan (2009); the strain
was identified there as C. simmonsii.
It is necessary to consider the possible conspecificity of C.
laticiphilum with three previously described taxa, all published
by Petch in the same paper (Petch 1906) from collections made
from Hevea in Sri Lanka. These were named as C. heveae,
Gloeosporium heveae [nomenclaturally unrelated to C. heveae]
and Gm. alborubrum. All three species were regarded as synonyms
of C. gloeosporioides by von Arx (1957).
Colletotrichum heveae was described with very wide conidia,
measuring 18–24 × 7.5–8 µm (Petch 1906), larger than any of
the species in the C. acutatum species complex, and possibly
www.studiesinmycology.org
75