Colletotrichum spaethianum (Allesch.) Damm, P. F. Cannon & Crous

Colletotrichum spaethianum (Allesch.) Damm, P. F. Cannon & Crous , Fungal Diversity 39: 74 (2009)

Fig. 9 View Figure 9

Description.

Associated with brown leaf spot of edible canna (Canna indica ). Sexual morph not observed. Conidiomata acervulus, immersed or semi-immersed. Conidiophores formed directly on hyphae, hyaline, septate, and branched, up to 60 μm long. Conidiogenous cells enteroblastic, hyaline, cylindrical, slightly inflated, 8–18 × 2–3 μm. Conidia hyaline, smooth-walled, aseptate, slightly curved, 13–22 × 3.5–4 μm (mean = 17 × 3.6 μm, n = 20). Appressoria single or in loose groups, dark brown, irregular in shape, sometimes slightly lobed, smooth-walled 7–19 × 5–7.5 μm (mean = 13 × 6 μm, n = 30). Chlamydospores and Setae are absent.

Culture characteristics.

Colonies on PDA reach 60 mm in diameter after 7 days of growth at 25 ° C in the dark, circular, with dull surfaces and entire margins. The upper view is cottony with medium density, greyish-white in the center, flat, fluffy, and pinkish-white in other parts. The reverse has dark grey to orange pigmentation in the center and primrose in other parts.

Material examined.

Thailand • Muang Chiang Mai, Mushroom Research Center , on edible canna (Canna indica ), 19 February 2023, Maryam Fallahi, dried culture MF 140-1 ( MFLU 24-0242 ), living culture, MFLUCC 24-0236 .

Notes.

Based on the phylogenetic tree generated in this study, strain MFLUCC 24-0236 grouped with Colletotrichum spaethianum (CBS 167-49, ex-epitype) in the C. spaethianum species complex by 100 % ML, 100 % MP bootstrap support, and 1.0 BYPP (Fig. 8 View Figure 8 ). The base pair differences between C. spaethianum strains MFLUCC 24-0236 and CBS 167-49 revealed no difference in ITS, gapdh, chs- 1, act, and tub 2. Colletotrichum spaethianum ( MFLUCC 24-0236 ) is similar to C. spaethianum (CBS 167-49). However, it produced slightly larger conidiogenous cells with an L / W ratio = 6 (8–18 × 2–3 μm in C. spaethianum ( MFLUCC 24-0236 ) vs. 6–16 × 3–4 μm (L / W ratio = 5.4) in C. spaethianum (CBS 167–49 )) and bigger appressoria (7–19 × 5–7.5 μm (L / W ratio = 2.2) in C. spaethianum ( MFLUCC 24-0236 ) vs. 7–9.5 × 5–7.5 μm (L / W ratio = 1.3) in C. spaethianum (CBS 167-49 )) ( Damm et al. 2009). Also, unlike C. spaethianum (CBS 167-49), setae were not observed in C. spaethianum ( MFLUCC 24-0236 ) ( Damm et al. 2009). In our phylogenetic analysis, C. spaethianum (CBS 167-49) clustered in a well-supported subclade with C. guizhouensis ( CGMCC 3.15112, ex-type), C. lilii ( CBS 109214 ), and C. bicoloratum (NN 055229). Colletotrichum spaethianum is similar to the other three species in conidial shape and differs in setae, which usually have an acute tip and a cylindrical to conical base in C. spaethianum . The appressoria of C. spaethianum have an irregular outline that is more or less lobed ( Damm et al. 2009). Colletotrichum spaethianum was first reported on dead stems of Funkia univittata from Germany ( Damm et al. 2009). It usually causes leaf spots and anthracnose on various hosts ( Liu et al. 2020; Ma et al. 2020; Sun et al. 2020). This study provided the first host record for C. spaethianum on edible canna in Thailand.