Annulusmagnus J. Campb. & Shearer, Mycologia 96(4):826 (2004)
Index Fungorum number: IF 28870
Sexual morph: Ascomata on wood separate to clustered, immersed to semi-immersed, erumpent or superficial with base slightly immersed, black, coriaceous, roughened on the outside with short setose-like hyphae, oblate to suboblate to globose, ostiolate with a prominent neck, venter 375–660 ´ 400–700 µm. Ascomal wall in longitudinal section 42–50 µm thick, comprised of three layers; outer layer of thick-walled cells occluded with dark brown amorphous material; middle layer of brown, thin-walled, isodiametric to laterally compressed, elongated cells; inner layer of hyaline, laterally compressed, elongated, hyaline cells; in surface view, black, opaque, in upper part of textura angularis covered with short protruding hyphae and in lower part of textura prismatica. Neck central, cylindrical to conical, 88–340 ´ 80–150 µm, black to dark brown, yellow at apex, wall 2-layered, outer layer of dark brown, laterally compressed thick-walled cells occluded with brown amorphous material, thicker at base of neck, inner layer of laterally compressed hyaline cells. In moist chambers, the asci and ascospores accumulate at the apex of the neck. Hamathecium paraphysate; paraphyses numerous, not immersed in gelatinous material, longer than asci, 165–210 µm long, 4–10 µm wide at base, tapering to 2–3 µm at apex, 2–7 septate. Asci functionally unitunicate, cylindrical, pedicellate, (114–)138–283 ´ 7–14 µm, separating from the hymenial layer at maturity (deciduous), expanding an additional 10–30 µm in length on contact with water, discharging ascospores by dissolution of basal one-third to one-half of ascus (backdoor discharge), with prominent, bi-partite, doughnut-shaped apical ring, 2–4 ´ 3–5 µm, tapering 1–2 µm from top to bottom, with a subapical flange that is not visible in glycerin, channel through pore 1–2 µm wide; ascus ring MLZ negative, lower part staining, upper part not staining in aqueous cotton blue and nigrosin. Ascospores hyaline, multi-guttulate, becoming pale straw-colored or pale brown with age, overlapping uni-seriate, becoming uni-seriate in water, fusoid, flattened or occasionally slightly concave on one side, 3-septate, 16–37 ´ 5–10 µm, smooth-walled in transmitted light, rough-walled in SEM, with or without a thin, and pressed gelatinous sheath. Asexual morph: Undetermined.
Notes: Campbell and Shearer (2004) introduced the genus Annulusmagnus for Annulatascus triseptatus based on LSU sequence data. Annulusmagnus triseptatuswas first collected from submerged wood in Brunei (Wong et al.1999a) and subsequently reported from Australia, Canada and the USA, on submerged corticated or decorticated wood in both lotic and lentic habitats (Campbell and Shearer2004). There is only one species reported in this genus (Campbell and Shearer2004).
Type species: Annulusmagnus triseptatus (Wong et al.) J. Campb. & Shearer, Mycologia 96(4): 826 (2004)