Chaetocapnodium polonicum Czachura, Janik & Piątek, 2025

Czachura, Paweł, Janik, Paulina & Piątek, Marcin, 2025, Chaetocapnodium magnum and Chaetocapnodium polonicum from conifer resins disclose an unknown lifestyle in the Capnodiales (Dothideomycetes), MycoKeys 119, pp. 315-333 : 315-333

Chaetocapnodium polonicum Czachura, Janik & Piątek sp. nov.

Figs 4 , 5

Etymology.

The name refers to Poland, where the fungus was collected.

Typus.

Poland • Świętokrzyskie Province, Kielce County, the Świętokrzyski National Park, Psarska Góra , on resin of Abies alba , 15 Oct. 2020, leg. P. Czachura (holotype: KRAM F-60026 ; culture ex-type: CBS 153156 = P 0024 ) .

Description.

Hyphae hyaline, subhyaline, or pale brown, smooth or slightly verruculose, branched, septate, frequently constricted at septa, anastomosing, 2–6 μm wide. Pycnidia globose, subglobose, or pyriform, formed intercalary or terminal on hyphae; peridium composed of pale olivaceous or pale brown pseudoparenchymatous cells arranged in textura angularis, 32.5–113.5 × 25.5–79.5 μm. Setae absent or present, aseptate or 1–3 - septate, brown or deep dark brown, 10–33 μm long. Ostiole absent or present, not well-developed or well-developed. Conidia release from ostiole or by rupture of peridium, hyaline or subhyaline, aseptate, globose or subglobose, smooth, 2.1–3.5 × 1.9–3.1 μm.

Culture characteristics.

Colonies on MEA slightly convex, dark iron grey or greyish white, reaching 14 mm diam. after 2 weeks at 15 ° C and 16 mm diam. after 2 weeks at 25 ° C, margin slightly crenate, reverse dark iron grey. Colonies on OA flat, dark iron grey with greyish white center, reaching 10 mm diam. after 2 weeks at 15 ° C and 19 mm diam. after 2 weeks at 25 ° C, margin entire, reverse dark iron grey. Colonies on PDA convex, dark iron grey, greyish white, or grey olivaceous, reaching 14 mm diam. after 2 weeks at 15 ° C and 19 mm diam. after 2 weeks at 25 ° C, margin lobate, reverse dark iron grey. Colonies on SNA flat, grey olivaceous, reaching 12 mm diam. after 2 weeks at 15 ° C and 17 mm diam. after 2 weeks at 25 ° C, margin nearly entire to slightly fimbriate, reverse grey olivaceous.

Notes.

Chaetocapnodium polonicum is closely related to Chaetocapnodium philippinense and Chaetocapnodium indonesiacum . It is not possible to compare the morphology of Ch. polonicum with Ch. philippinense since the former is known only from its asexual morph and the latter from its sexual morph ( Liu et al. 2015; Abdollahzadeh et al. 2020). However, Ch. polonicum differs from Ch. philippinense in LSU (2 bp), ITS (2 bp), tef 1 (8 bp), and rpb 2 (16 bp) sequences, which is an adequate genetic distance for distinguishing species in the genus Chaetocapnodium (see Discussion). It is also worth noting that, although not directly comparable between asexual and sexual morphs, setae in the sexual morph of Ch. philippinense are up to 90 μm long (measurements taken from illustrations of this species in the original publication: Liu et al. 2015). Thus, they are significantly longer than setae in the asexual morph of Ch. polonicum .

Morphologically, Chaetocapnodium polonicum is significantly different from Ch. indonesiacum ( Abdollahzadeh et al. 2020) . Chaetocapnodium polonicum produces pycnidia (reaching 113.5 μm) and the longest setae (reaching 33 μm long) observed in asexual morphs (pycnidia) of all described Chaetocapnodium species, in contrast to Ch. indonesiacum , which has significantly smaller pycnidia (( 20 –) 25–35 (– 48) μm) and lacks setae. Moreover, Ch. polonicum forms well-developed ostioles (if present), in contrast to Ch. indonesiacum , in which ostioles are not well-developed (if present), and Ch. polonicum produces slightly larger conidia (reaching 3.5 μm) than Ch. indonesiacum (reaching 2.8 μm). Finally, both species significantly differ in growth rate; colonies of Ch. polonicum reached 16 mm diam. after 2 weeks at 25 ° C, in contrast to colonies of Ch. indonesiacum that reached 43 mm diam. in the same conditions.

Figures

Figure 4. Morphology of cultures of Chaetocapnodium polonicum (CBS 153156) after 2 weeks at 25 ° C. A, B. Colony on MEA; C, D. Colony on OA; E, F. Colony on PDA; G, H. Colony on SNA.

Figure 5. Morphology of Chaetocapnodium polonicum (CBS 153156). A. Hyphae; B. Anastomosing hyphae; C, D. Pycnidia formed intercalary on hyphae; E. Pycnidium with setae; G – I. Pycnidia with released conidia through ostioles; J. Well-developed ostiole; K – M. Setae; N. Conidia. Scale bars: 10 μm.