Fig 4. Valsaria ostryae: Asexual morph (MFLU 17–0837).

a-c Culture characteristics and mycelium. d,e hyphae with denticles and conidia (partly budding). f-j Phialides. j-o Conidia. Scale bars: c = 1000 μm, d = 20 μm, e = 10 μm, f-j = 10 μm, j-o = 10 μm. Notes–Valsaria ostryae resembles V. insitiva (type species), in having pseudostromatic stromata, pseudoparenchymatous ectostroma, bitunicate asci containing short cylindrical ring and ellipsoid, dark brown ascospores. However, V. ostryae differs from V. insitiva in having narrower pseudoparaphyses (2–3 μm vs. 1.5–5 μm), guttule number in each ascospore cell (0 vs. 2–3) and in ornamentation and constriction of the ascospores. The ascospores are deeply constricted at septum and finely warted to reticulate in V. ostryae while those of V. insitiva are not or hardly constricted at the septum and finely tuberculate. Our multi-gene phylogeny suggests that V. ostryae is related to V. lopadostomoides and V. rudis but phylogenetically segregated from them with strong bootstrap support (100% ML, 100% MP, 1.00 PP). Valsaria ostryae has smaller stromata (500–800 μm high, 1000–1500 μm diam v.s 1200–1400 μm high, 1700–2500 μm diam), shorter asci (82–131 × 9–12 μm v.s (112–)115–128(–136)×(10.5–)11.0–14(–15.5) and have different ascospore ornamentation (finely warted to reticulate v.s distinctly warted, reticulate or spotted). Our new taxon is also morphologically different from V. rudis in having smaller stromata1000–1500 μm diam v.s 1200–1700 μm high, 1200–2500 μm diam) and smaller ascomata (277–479 μm high, 284–603 μm diam, v.s 3000–6000 μm high, 2000–5000 μm diam), Furthermore, a comparison of 600 nucleotides across the ITS (+5.8S) gene regions between V. ostryae and V. rudis reveals 5.31% base pair differences and that of V. ostryae and V. lopadostomoides reveals 6.60% base pair differences respectively. Hence, V. ostryae is introduced as a new species in the genus Valsaria.