Erysiphe pakistanica Afshan, Riaz & Khalid, 2022

Afshan, Najam-Ul-Sehar, Riaz, Maria, Liaqat, Nida, Majeed, Javeria, Jabeen, Muhammada, Niazi, Abdul Rehman, Khalid, Abdul Nasir, Zafar, Irsa & Afzal, Saliha, 2022, Erysiphe pakistanica (Erysiphaceae), a new species on Indian willows (Salix tetrasperma) from Pakistan, Phytotaxa 545 (1), pp. 57-68 : 63-66

Erysiphe pakistanica Afshan, Riaz & Khalid sp. nov. ( Figs 3 , 4 ) MycoBank no. 837810

Etymology:— pakistanica refers to Pakistan, from where the type specimen was collected.

Holotype:— PAKISTAN. Khyber Pakhtunkhwa Province: Hazara division, District Abbottabad, Thandiani 2,750 m a. s. l., on Salix tetrasperma Roxb. , 13 August 2018, Najam-ul-Sehar Afshan & Nida Liaqat ZM17 ( LAH 36170). GenBank no.: MW 183140 ( ITS), MZ 340364 ( LSU).

Description:— Mycelium amphigenous, filicolous, dispersed covering almost whole leaf, evanescent to persistent, white; hyphae hyaline, thin, smooth-walled. Hyphal appressoria solitary, nipple-shaped, 4–5 µm diam. Conidiophores arising from superficial hyphae, erect, straight to slightly curved, 44–100 µm long (including conidia), 8–14 µm wide, composed of short foot cell, constricted at basal septum, followed by 1–2 shorter cells, 21–24 µm long. Conidia cylindrical, subcylindrical or doliiform, with fibrosin bodies, 19–27 × 9–14 µm. Germ tube terminal, aseptate, short, ending with swollen appressorium. Chasmothecia scattered to gregarious, brown to black, 116–140 µm diam. Peridium cells conspicuous, polygonal to sub-circular, thick-walled, 24–39 × 15–30 µm. Appendages 20–35 per chasmothecium, straight, arising both polar and equatorial sides, rough from bottom, smooth towards apex, mostly hyaline but rarely pigmented towards base, with single basal septum, apex uncinate-circinate, 5–8 × 198–230 µm. Asci 7–8 per chasmothecium, mostly stalked, rarely sessile, hyaline, globose, subglobose or ellipsoidal, 27–43 × 57–74 µm, 3–5 spored. Ascospores hyaline, ellipsoidal to ovoid, 12–19 × 23–30 µm.

Additional material examined:— PAKISTAN. Khyber Pakhtunkhwa:Abbottabad District, Khanspur, 2250 m. a. s. l., on Salix tetrasperma with teleomorphic stage, 30 October 2018, Najam-ul-Sehar Afshan & Javeria Majeed (LAH 36140), GenBank no.: MW183121 (ITS); with anamorphic stage, ibid., 7 September 2020, Najam-ul-Sehar Afshan IMH06 (LAH36955), GenBank no.: MZ336462 (ITS), MZ340365 (LSU); Khyber Pakhtunkhwa:Abbottabad District, Thandiani, 2,750 m. a. s. l., on S. tetrasperma , with anamorphic stage, 9 September 2020, Najam-ul-Sehar Afshan IMH16 (LAH 36956), GenBank no.: MZ363672 (ITS); Khyber Pakhtunkhwa: Abbottabad District, Khanspur, 2410 m. a. s. l., on S. tetrasperma , with anamorphic stage, 16 August 2020, Najam-ul-Sehar Afshan PM22 (LAH 37013), GenBank no.: OM417199 (ITS); Azad Jammu Kashmir, Bagh, 1676, m. a. s. l., on S. tetrasperma , with teleomorphic stage, 7 December 2021, Najam-ul-Sehar Afshan AJK02 (LAH 37011), GenBank no.: OM403469 (ITS).

Figures

FIGURE 3. A. Infected leaves of Salix tetrasperma (LAH 36170, holotype). B. LAH 36140. C. Infection under stereomicroscope. D. Chasmothecial appendages. E. Chasmothecia. F.Asci with ascospores. G. Conidiophore. H. Appressorium. I. Germinating conidium. J, K. Conidia. Scale bars:A, B = 5 cm, C = 5 mm, D–F = 50 µm G, H = 20 µm, I–K = 10 µm. Photos by Maria Riaz.

FIGURE 4. Line drawings of A. Chasmothecium. B. An Ascus with ascospores. C. Chasmothecial appendages. D. A Conidiophore. E. Conidia. Scale bars:A–C = 50 µm, D = 20 µm, E = 10 µm. Drawings by Maria Riaz.