Allocucurbitaria ulmi (Jaklitsch & Voglmayr.) M. Mehrabi-Koushki & Eisvand, in Eisvand, Mehrabi-Koushki & Crous, Mycol. Progr. 23(no. 14): 7 (2024)
Index Fungorum number: IF 823021; MycoBank number: MB 823021, Facesoffungi number: FoF 15893
Basionym: Seltsamia ulmi Jaklitsch & Voglmayr, Stud. Mycol. 90: 113. 2017.
Etymology – For its occurrence on Ulmus.
Description – Ascomata (480–)524–760(–870) μm diam (n = 14), pyriform, black, immersed singly or in valsoid groups of up to ca. 10 individuals, upright or oblique, usually with ostiolar necks convergent to a common centre, surrounded by subiculum, slightly lifting the bark forming bumps, becoming visible through bark fissures. Ostiolar necks forming more or less stout papillae 150–300 μm diam, when young whitish to yellowish inside. Peridium leathery, black, ca. 40–160 μm thick, consisting of a narrow opaque outer layer of dark brown thick-walled cells (4.8–)8–14.5(–17) μm diam (n = 60), a median brown t. angularis of thin-walled and similarly sized cells, and an inner layer of brown compressed cells. Subicular hyphae originating on the ascoma surface, densely woven, making measurement of peridial thickness difficult, dark brown, thick-walled, 3–8 μm wide. Hamathecium consisting of 1–3.5(–4) μm wide, agglutinated, branched ?paraphyses. Asci (310–)346–419(–457) × (30–)35–44(–52.5) μm (n = 32), cylindrical, with a distinct ocular chamber, a slightly elongated stipe and a simple base, containing 8 uni- to partly biseriately arranged ascospores. Ascospores (52.5–)58.5–67(–71.5) × (16–)18.8–22.5(–26) μm, l/w (2.5–)2.8–3.3(–3.7) (n = 85), fusoid to subclavate, with the upper part slightly widened, first yellow, with 3 main septa, later brown, finally with numerous, ca. 17–25 transverse and 3–7 longitudinal septa, surrounded by a sheath around each hemisphere, quickly swelling and losing contours in water. (Jaklitsch et al. 2018)
Cultures – Mycelium filling a 90 mm Petri dish on MEA, when centrally inoculated, after 36 d at room temperature. Colony dense, dark olive-brown, odour indistinct, no asexual morph detectable.
Habitat – On Hapalocystis bicaudata on corticated Ulmus glabra.
Distribution – Only known from the holotype in Norway.
Typus – Norway, Aust-Agder, Froland kommune, Ytre Lauvrak, associated with Hapalocystis bicaudata on corticated twigs of Ulmus glabra (Oleaceae), 3 Oct. 2014, H. Voglmayr & W. Jaklitsch (holotype, WU 36957, ex-holotype culture CBS 143002 = L150).
Notes – Seltsamia was published on 21 Nov. 2017, with the type species Seltsamia ulmi (CBS 143002) isolated from corticated Ulmus glabra in Norway (Jaklitsch et al. 2018). The sexual morph is exceptional among the members of the Cucurbitariaceae because of swollen ascospore sheath.
Figure 1 – Allocucurbitaria ulmi (WU 36957). A. Horizontal section at the ostiolar level. B. Horizontal section at the ascomatal level. C, D. Ascoma in vertical section. E. Peridium in vertical section showing remnants of subicular hyphae. F–H. Asci (young in F). I. Ascus apex showing ocular chamber. J–Q. Ascospores (showing swelling sheath in J and K). E, J. in 3 % KOH. Scale bars: A–C = 200 μm; D = 100 μm; E–H, K = 25 μm; I = 10 μm; J, L–Q = 15 μm.