Freshwater Ascomycetes - Species Monograph

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Genus	Species	Author
Annulusmagnus	triseptatus	(S.W. Wong, K.D. Hyde et E.B.G. Jones) J. Campb. et Shearer
Class	Order	Family
Sordariomycetes	Sordariales	Annulatascaceae

Genbank ID: 194178

Synonymy:

Basionym: Annulatascus triseptatus S.W. Wong, K.D. Hyde et E.B.G. Jones. Mycol. Res. 103: 563. 1999.

Description

Habit:

Ascomata separate to clustered, immersed, partly immersed or superficial on submerged wood.

Ascomata:

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 x 400–700 µm.

Peridium:

Peridium 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.

Beak:

Beak central, cylindrical to conical, 88–340 x 80–150 mm, 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:

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.

Ascus:

Asci functionally unitunicate, cylindrical, pedicellate, (114–) 138–283 x 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 1/3 to 1/2 of ascus (back-door discharge), with prominent, bipartite, doughnut shaped apical ring, 2–4 x 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.

Ascospore:

Ascospores hyaline, multiguttulate, becoming pale straw colored or pale brown with age, overlapping uniseriate, becoming uniseriate in water, fusoid, flattened or occasionally slightly concave on one side, 3 septate, 16–37 x 5–10 µm, smooth walled in transmitted light, rough walled in SEM, with or without a thin, adpressed gelatinous sheath.

Sheath:

Sheath present or absent, thin and adpressed when present.

Appendage:

Not present.

Culture:

Colonies on peptone-yeast-glucose (PYG) agar immersed, brown, spreading, comprised of brown, septate, branched hyphae.

Anamorph:

None observed.

Other info

Type & Location:

AUSTRALIA: Koah, Clohesy River, on submerged wood, 31 Dec 1991, K.D. Hyde, HKU 889 (Neotype).

Other Specimens:

Additional specimens examined were collected from Canada (Ontario and Manitoba), the USA (AR, IL, ME, MI, MN, NC, NH, NY, OR, TN, VA, WI) and Venezuela. Detailed collection information has been deposited with the herbarium specimens (ILL).

Substratum:

Submerged corticated or decorticated wood in both lotic and lentic habitats; causes soft-rot cavities on balsa wood in culture.

Habitat:

Lentic and lotic habitats.

Distribution:

Widespread.

Pertinent Literature:

Wong et al. 1999; Campbell & Shearer 2004.

Comments:

Additional Pictures

Asci, ascospores, back door discharge
Back door discharge
Ascospores mounted in glycerin under oil immersion
Ascus
Ascus stained in aqueous cotton blue

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