Diaporthe rhoicola Crous [as 'rhusicola'], in Crous, Groenewald, Shivas, Edwards, Seifert, Alfenas, Alfenas, Burgess, Carnegie, Hardy, Hiscock & Hübe, Persoonia 26: 135 (2011)
Index Fungorum number: IF 827844; Facesofungi number: FoF 02889
Synonym: Diaporthe baccae L. Lombard, G. Polizzi & Crous, Phytopath. Mediterr. 53(2): 93 (2014).
Saprobic on a dead branch of Prunus sp. Sexual morph: Undetermined. Asexual morph: Conidiomata pycnidial in culture on PDA, 416–747 μm (x̄ = 622.4 μm, n = 10) diameter, solitary, scattered, or aggregated, globose to conical, brown to black, surface covered with hyphae, cream to pale luteous conidial mass. Pycnidial wall composed of light brown, thick-walled cells of textura angularis. Alpha conidia 7–13 × 1–4 μm (x̄ = 9.5 × 2.5 μm, n = 40), hyaline, aseptate, smooth-walled, fusoid to ellipsoidal, straight, tapering towards both ends, subobtuse at the apex, subtruncate at base, guttulate. Beta conidia 21–35 × 0.7–3 μm (x̄ = 28.7 × 1.8 μm, n = 40), hyaline, aseptate, smooth-walled, spindle-shaped, strongly curved, truncated base, apex acutely rounded, tapering from the middle towards the apex. Gamma conidia 3–8.5 × 2–5 μm (x̄ = 5.8 × 3.5 μm, n = 40), hyaline, aseptate, smooth-walled, fusoid to ellipsoidal, straight, subobtuse at the apex, subtruncate at base, guttulate.
Culture characteristics: Colonies on PDA reach 80 mm diameter after 14 days at 18 °C, surface initially white, turning cream to smoke-grey, reverse turns from smoke gray to grayish sepia, with flattened, dense and cottony mycelium.
Material examined: ITALY, Forlı`-Cesena Province, Fiumana di Predappo, on dead aerial branch of Prunus sp. (Rosaceae), 19 January 2016, E. Camporesi (MFLU 16-0295), ex-type living culture MFLUCC 16-1393, KUMCC 16-0129.
GenBank: ITS: KY684947, TEF1:KY684946, b-tubulin:KY684945.
Notes: Diaporthe rhusicola has been reported from California and South Africa on several hosts including, Juglans regia, Prunus dulcis, and Rhus pendulina (Crous et al. 2011, Chen et al. 2015). The species was originally described by Crous et al. (2011) from leaves of Rhus pendulina in South Africa. Lombard et al. (2014) introduced another similar Diaporthe species, D. baccae on Vaccinium corymbosum in Italy. However, D. rhusicola was not included in the phylogenetic analysis of Lombard et al. (2014). Based on our phylogenetic analysis of combined ITS, TEF1, and b-tubulin sequence data of Diaporthe species (Hyde et al. 2017), our strain (MFLUCC 16-1393) clustered with the ex-type strain of D. rhusicola (CBS 129528) and ex-type strain of D. baccae (now synonymized as D. rhusicola, CBS 136972) with relatively high support (82%MP/1.00PP and 100%MP/1.00PP respectively). When comparing our isolate with the type specimen of D. rhusicola (CBS 129528), they are similar in morphology. Pycnidia of our strain are slightly larger than that of type specimen. Even though beta and gamma conidia were observed in our specimen, these are not observed in the type specimen. Based on morphology and molecular phylogeny, we synonymize D. baccae under D. rhusicola as the latter is the oldest available name (Hyde et al. 2017).