Erysiphe amphicarpaeicola M. Bradshaw 2025, sp. nov.

Erysiphe amphicarpaeicola M. Bradshaw sp. nov. Fig. 5 Etymology. Epithet composed of the name of the host genus and the Latin-derived suffix “ - cola ” (dweller). Diagnosis. Morphologically distinguished from Erysiphe glycines by having chasmothecia with shorter appendages, up to twice as long as the chasmothecial diameter (versus up to seven times as long as the diameter in E. glycines), and phylogenetically by forming a distant highly supported clade. Type. USA • North Carolina, Ashe County, near West Jefferson, on leaves of Amphicarpaea bracteata, along Bluff Mountain logging road, 36°23'26.9"N, 81°33'21.2"W, 14 September 2024, J. Thompson (NCSLG 25124 — holotype). Ex-holotype sequence: PV 416665 (ITS), PV 472002 (GAPDH), PV 471964 (GS). Description. Mycelium amphigenous, forming effuse, arachnoid, whitish patches; hyphae branched, often at right angles, septate, hyaline, thin-walled, smooth, 3–5 µm wide; hyphal appressoria solitary, nipple-shaped to lobate, 4–10 µm wide; conidiophores 65–80 µm long, septate at base, foot cells 24–42 µm long and 6–8 µm wide, straight to usually somewhat flexuous, sinuous, followed by 1–2 shorter cells, about 15–20 × 7–8 µm conidia formed singly, cylindrical-doliiform, 23–35 × 10–12 µm, germination not seen. Chasmothecia scattered, subglobose to globose, dark brown, 90–154 × 104–157 µm in diameter; peridium cells irregularly polygonal, 6–13 × 10–19 µm; appendages in the lower half of the chasmothecium, number variable, few to numerous, mycelioid, often interwoven with the mycelium and with each other, sometimes poorly developed and hard to distinguish from the mycelial hyphae, length variable (up to two times the diameter of the chasmothecium), thin-walled, smooth, narrow (up to 4 µm wide), septate, hyaline; asci 4–6 per chasmothecium, 63–70 × 38–45 µm, oblong-ellipsoid, short-stalked, 6 - spored; ascospores ellipsoid-ovoid, 20–22 × 11–12 µm, colorless. Additional specimens examined. (all on leaves of Amphicarpaea bracteata): USA • North Carolina, Macon County, Cashiers, along roadside, 35°00'59"N, 83°07'37"W, 2024, June 2024, J. Thompson 100 (NCSLG 25142); • Shortoff Mountain along trail, 35°00'59"N, 83°07'37"W, June 2024, J. Thompson 101. (NCSLG 25141); • Macon County, Highlands, on leaves of Amphicarpaea bracteata along roadside, 16 September 1975, L. F. Grand 2095 (NCSLG 22551). Substrate / host. Amphicarpaea bracteata. Distribution. North America (Canada, USA), probably widespread. Notes. Amano (1986) listed Amphicarpaea bracteata as host of Erysiphe communis from Canada and the United States. Braun and Cook (2012) assigned North American Erysiphe specimens on A. bracteata to E. glycines, an Asian species that occurs on Glycine spp. and Amphicarpaea edgeworthii. This decision was based on the morphological similarity between Asian and North American specimens. Sequences retrieved from Asian collections on Glycine spp. and Amphicarpaea edgeworthii form a strongly supported species clade within the basal Uncinula lineage within Erysiphe (Bradshaw et al. 2023 b). The North American E. amphicarpaeicola clade also clusters in the Uncinula lineage, far from E. glycines (Fig. 2). Based on the examined specimens, chasmothecia on A. bracteata differ from E. glycines chasmothecia in having shorter appendages, up to twice as long as the chasmothecial diameter (versus up to seven times as long as the diameter).