Heterosphaeria patella (Tode) Grev., Scott. crypt. fl. 1: pl. 103 (1824)
Saprobic on dead stems of Malva sp. (Malvaceae). Sexual morph: see Leuchtmann (1987). Asexual morph: Conidiomata 100–200 µm diam., 100–150 µm high, black, discoid in outline, solitary to gregarious or occasionally confluent, pycnidial, globose to subglobose in section view, semi-immersed to superficial, unilocular, lacking obvious setae, with brown to dark brown hyphae developing from conidiomatal base on substrate. Ostiole absent. Conidiomatal wall 20–30 µm wide, composed of thick-walled, dark brown cells of textura globulosa at outer part, gradually merging with thin-walled, pale brown to hyaline cells of textura angularis lining the cavity. Conidiophores lining the base and sides of the conidiomatal cavity, hyaline, septate and branched, smooth, invested in mucus. Conidiogenous cells 10–20 × 2–5 µm, hyaline, holoblastic, sympodial, cylindrical to subcylindrical, terminal to integrated, indeterminate, smooth, with 2 to several, small, indistinct protuberant conidiogenous loci towards the apices. Conidia 18–26 × 2.5–4 µm ( = 21 × 3 µm; n = 30), hyaline, fusiform, 1–2-septate, slightly constricted at the septa, guttulate, smooth, thick-walled, without appendage, basal cell long obconic with a truncate base, apical cell shortly rostrate.
Material examined: Italy, Province of Forlì-Cesena, Bagno di Romagna, near Lago Pontini, on dead aerial stems of Malva sp. (Malvaceae), 1 July 2015, Erio Camporesi, IT2551 (MFLU 15-2272), (KUN, HKAS 93632).
Notes: Our collection is considered as the asexual morph of Heterosphaeria patella with sequence similarities between MFLU 15-2272/IT2551, and H. patella (MF196187) of 100% (734/734) in LSU and 99% (479/482) in ITS. The asexual morph of H. patella differs from asexual morph of H. linariae in the form of conidiomata and conidia. Heterosphaeria patella has brown to dark brown hyphae developing from the conidiomatal base, while this character is absent in H. linariae. In addition, Heterosphaeria linariae has 3–4-septate conidia bearing appendages at each end, whereas H. patella has 1–2-septate conidia without appendages. The differences between H. linariae and H. patella may correlate with protein gene sequence (e.g., rpb2). We found that there are 55 base pairs differences in rpb2 sequence between MFLU 15-2272/IT2551 and MFLU 19-2866/IT1847. Hence it is necessary to include higher resolution protein coding genes to better understand the taxonomy of species in Heterosphaeria.
Heterosphaeria patella (asexual morph, MFLU 15-2272) a Herbarium specimen. b, c Appearance of black coniodiomata on the host. d, e Vertical section of conidiomata. f Section of peridium. g–i Conidiophores, conidiogenous cells and developing conidia. j–m Conidia. Scale bars d–e = 100 µm, f = 20 µm, g–j = 10 µm, k–m = 5 µm.
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.