Fungalpedia – Note 646, Polychaeton
Polychaeton (Pers.) Lév.
Citation when using this data: D. S. Marasinghe et al. 2023 (in prep.) – Fungalpedia, Ascomycota.
Index Fungorum, Facesoffungi, MycoBank, GenBank.
Classification: Capnodiaceae, Capnodiales, Dothideomycetidae, Dothideomycetes, Pezizomycotina, Ascomycota, Fungi
Saprobic on sugary exudates from insects, dark mycelium forming a soot-like coating on the upper surface of leaves. Mycelium superficial hyaline to brown, branched, consisting of smooth, thin-walled, septate hyphae, constricted at septa, with a mucilaginous outer wall layer. Sexual morph: Undetermined. Asexual morph: Conidiomata pycnidial, supported on a black mycelial network, narrow and cylindrical stalks composed of tightly compacted, anastomosed, synnematous cylindrical hyphae, lageniform with a brown oval or ellipsoid part which produces conidia and a long neck. Pycnidium wall composed of 2 or more layers, the outer one being more or less pseudoparenchymatous although the short cells tend to be arranged linearly, indicating their origin from longitudinally fused hypha. Ostiole surrounded by hyaline, subulate, hyphal extensions. Conidia small, oblong to ellipsoid, continuous, aseptate, hyaline, smooth-walled, arranged in a droplet at the apex of pycnidium (Abdollahzadeh et al. 2020).
Notes: Persoon (1822) established Polychaeton as a subgenus in Fumago. Later Léveillé (1847) established Polychaeton as a separate genus to accommodate coelomycetes with rostrate pycnidia with a wider base topped by a fimbriate or smooth rostrum (Inacio and Dianese 1998). It forms a mitosporic centrum within a wide stalk, located from the central to the upper part and Batista and Ciferri (1963b) placed these species under Microxyphium. Hughes (1976) described Polychaeton as stalked pycnidia with an ellipsoidal pycnidial cavity, indistinct swelling with a neck composed of hyaline hyphal extensions and did not follow Batista and Ciferri (1963a). Polychaeton was considered as the asexual morph of Capnodium by Chomnunti et al. (2011). However, Abdollahzadeh et al. (2020) examined an isolate of P. citri from Iran and found it clustered in a distinct clade close to Conidiocarpus and Phragmocapnias. Polychaeton is morphologically similar to the asexual morph of Capnodium by flask-shaped, dark brown to brown, ostiolate, long-necked pycnidia with aseptate, hyaline, ellipsoidal conidia. However, Polychaeton differs from Capnodium by lacking a stalk (Fig. 1).
≡ Fumago sect. Polychaeton Pers., Mycol. eur. (Erlanga) 1: 9 (1822).
Type species: Polychaeton quercinum (Pers.) Kuntze (1891).
Other accepted species: Species Fungorum – search Polychaeton.
Figure 1 – Polychaeton artocarpi. a Bottle shaped pycnidia. b Conidia. Scale bars: a = 50 μm, b = 10 μm. Redrawn from Khodaparast (2006)
References
Batista AC, Ciferri R 1963a – Capnodiales. Saccardoa 2:1–298.
Batista AC, Ciferri R 1963b – The sooty-molds of the family Asbolisiaceae. Quaderno. Laboratorio Crittogamico, Istituto Botanico Della Università Di Pavia 31:23–229.
Chomnunti P, Schoch CL, Aguirre-Hudson B et al 2011 – Capnodiaceae. Fungal Divers 51:103–134.
Hughes SJ 1976 – Sooty moulds. Mycologia 68:693–820.
Inacio CA, Dianese JC 1998 – Some foliicolous fungi on Tabebuia species. Mycol Res 102:695–708.
Entry by
Diana Sandamali Marasinghe, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, 57100, Thailand School of Science, Mae Fah Luang University, Chiang Rai, 57100, Thailand, Mushroom Research Foundation, 128 M.3 Ban Pa Deng T. Pa Pae, A. Mae Taeng, Chiang Mai, 50150, Thailand
Published online 29 August 2023