Diplodia crataegicola Dissanayake, Camporesi & K.D. Hyde.
Index Fungorum number: IF551316; Facesoffungi number: FoF00885; Fig. 2
Etymology: Referring to the host Crataegus sp.
Holotype: MFLU 15-1311
Saprobic on dead branch of Crataegus sp. Sexual morph: Undetermined. Asexual morph: Conidiomata 220 – 265 μm high × 260 – 380 μm diam. (x̄ = 245 × 340 μm, n = 10), pycnidial, stromatic, solitary or clustered, immersed in the host, erumpent at maturity, dark brown to black, ostiolate, apapillate. Peridium 25 – 35 μm wide, outer and inner layers composed of dark brown and thin-walled hyaline textura angularis. Conidiogenous cells 10 – 22 μm high × 4 – 6 μm wide, hyaline, thin – walled, smooth, cylindrical, swollen at the base, discrete, producing a single conidium at the apex. Conidia 11 – 16 × 6 – 10 μm (x̄ = 14 × 9 μm, n = 50), aseptate, globose to subglobose, widest in the center, with rounded apex, initially hyaline, becoming dark brown before release from the pycnidia, wall moderately thick, externally smooth, internally roughened. Spermatia rod – shaped with obtuse ends, hyaline, thin – walled, smooth, 3 – 5 × 1.5 – 2 μm.
Cultural characteristics – Conidia germinating on WA within 12 h and germ tubes produced from lower end. Colonies growing on PDA, covering the entire plate in 5 days at 28 °C, mycelium grey to olivaceous black at the surface and olivaceous black from below.
Material examined – ITALY, Province of Forlì – Cesena [FC], Passo del Barbotto – Mercato Saraceno, on dead branch of Crataegus sp. (Rosaceae), 3 November 2012, E. Camporesi, IT 875 (MFLU 15-1311, holotype), ex-type living cultures, MFLUCC 15–0648, KUMCC15-0075, CFTCC15-0002.
Notes – Conidial length of all reported Diplodia species range from 21.5 to 52.5 μm and width vary from 10 to 22 μm (Phillips et al. 2013). The small conidia of Diplodia crataegicola (14 × 9 μm, L/W ratio = 1.55) clearly distinguish this species from all other reported species (Fig. 2). Diplodia crataegicola is phylogenetically most closely related to D. seriata (Fig. 1), and the two species can be separated on the shapes and dimensions of their conidia.
Fig. 1 Phylogram generated from RAxML based on combined ITS, EF and β-tubulin sequenced data for Diplodia species. Maximum likelihood bootstrap support values and Bayesian posterior probabilities greater than 50 % and 0.90 are indicated above the nodes. Only ex-type and voucher strains are used and the new isolates are in blue. The tree is rooted with Endomelanconiopsis endophytica CBS 120397.
Fig. 2 Diplodia crataegicola (holotype) a, b Conidiomata on host substrate c, d Cross section of conidiomata e, g Immature and mature conidia attached to conidiogenous cells h Immature conidium i – k Mature conidia l Germinating conidia m Spermatogenous cells and spermatia. Scale bars: a = 2 mm, b = 500 μm, c = 100 μm, d = 75 μm, e, f = 50 μm, g – m = 15 μm.