Pseudocamarosporium quercinum Wijayaw., Camporesi & K.D. Hyde, sp. nov., Index Fungorum number: IF551300
Etymology: Named after the generic name of the host
Saprobic on dead branches and stems of Quercus pubescens. Sexual morph: Undetermined. Asexual morph: Conidiomata 420–450 μm diam., 250–280 μm high, pycnidial, immersed, erumpent, solitary, globose, unilocular, black, with a long neck. Pycnidial wall 50–70 μm wide, multi-layered, with 3–5 outer layers of brown-walled cells of textura angularis, with inner layer thin, hyaline. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 2–7 × 3–5 μm, blastic, phialidic, discrete, determinate, hyaline, smooth. Conidia 15–18 × 6–7.5 μm (mean = 16.41 × 6.79 μm, n = 20), oblong, mostly straight, occasionally slightly curved, muriform, with 1–4 transverse and 1–2 longitudinal septa, continuous, initially hyaline, later becoming brown to dark brown at maturity, narrowly rounded at both ends, smooth-walled.
Culture characteristics: Colonies on PDA slow growing, reaching 1.5 cm diam. after 1 week at 18 °C, dense mycelium, circular, rough margin white at first, greenish white after 1 week, flat or effuse on the surface. Hyphae septate branched, hyaline, thin.
Material examined: ITALY, Province of Forlì-Cesena [FC], Pian di Spino – Civitella di Romagna, on dead branches of Quercus pubescens (Fagaceae), 2 December 2013, Erio Camporesi, IT 1552 (MFLU 15–0733, holotype), (HKAS 88741, isotype); living cultures MFLUCC 14–0456 = GUCC 54.
Notes: There have been several camarosporium-like taxa reported on Quercus spp. viz. Camarosporium betulinum Died. (14–20 × 5–7.5 μm), C. juglandis Ellis & Barthol. (12–25 × 8–12 μm), C. kursanovii Mekht. (7–16.3 × 7–9 μm), C. quercus Sacc. & Roum. (25–28 × 8–10 μm), C. variabile (Berk. & M.A. Curtis) Sacc. (30–60 μm long) (Ellis & Ellis 1985; Farr and Rossman 2016). Our collection is morphologically distinct from all above taxa and in molecular analyses resides in Didymosphaeriaceae with other Pseudocamarosporium species.
Fig. 2 Pseudocamarosporium quercinum (holotype). a, b. Immersed conidiomata on dead branches of Quercus pubescens. c. Vertical section of pycnidium. d. Vertical section of the neck of pycnidium. e. Conidioma wall. f-i. Developing conidia attach to conidiogenous cells. j-m. Conidia. Scale bars: a = 500 μm, b = 200 μm, c = 50 μm, d = 20 μm, e = 10 μm, f-m = 5 μm.