Freshwater Ascomycetes - Species Monograph

Click on the pictures below to view them at their full size.

Genus	Species	Author
Ophioceras	arcuatisporum	Shearer, J.L. Crane & Chen
Class	Order	Family
Sordariomycetes	Inc. sed.	Magnaporthaceae

Synonymy:

Description

Habit:

On submerged herbaceous debris.

Ascomata:

Ascomata superficial to immersed, sometimes horizontal on the substratum, clustered or scattered, globose to elongated globose, 313-324 x 252-340 µm, black with a long erumpent beak.

Peridium:

Ascomal wall 4 to 6 cell layers thick, 20 µm wide, width even throughout, thickened somewhat near base of beak, of globose to elongated globose pseudoparenchyma, walls of outer cells covered with brown amorphous material, of textura angularis in face view.

Beak:

Beak central, cylindrical, undulate, periphysate, wall of textura angularis in face view, of pseudoparenchymatic cells pigmented brown, hairy, up to 800 µm long, 94-162 µm wide.

Hamathecium:

Hamathecium of hyaline, septate paraphyses which are broad at base, tapering toward the apex, shorter than asci.

Ascus:

Asci fusoid to narrowly cylindrical 276-307 x 15-20 µm, with a very small, thimble-shaped apical apparatus staining blue in aqueous cotton blue, astipitate, containing eight ascospores in a single fascicle, separating from the hymenial layer.

Ascospore:

Ascospores narrowly fusoid to cylindrical, falcate, sometimes with one end more broadly rounded than the other, 170-239 (x= 197.7, s= 17.0, n=30) x 4-7 (x= 5.0, s= 0.9, n= 30) µm, 5-12 septate, hyaline to pale orange in transmitted light, orange in mass, apices staining in aqueous cotton blue; ascospores frequently released by deliquescence of basal half of ascus.

Sheath:

Appendage:

Culture:

Colonies on cornmeal agar spreading, floccose, immersed and superficial, dark grey, black in reverse.

Anamorph:

None observed.

Other info

Type & Location:

HOLOTYPE. U.S.A. MINNESOTA: Lake Itasca State Park, Elk Lake, on Typha sp., 22 Oct 1993, JLC, A-167-1, ILLS.

Other Specimens:

U.S.A. MINNESOTA: St. Louis County, Shagawa Lake, on submerged herbaceous debris, 23 Oct 1993, JLC, A-167-2, ILLS; WISCONSIN: Green Bay, on herbaceous debris in the strand line, 13 Sep 1986, CAS, CS-787-1, ILLS, ATCC 66338; CANADA. MANITOBA: Lake Rosabella, on submerged grasses, 25 Jul 1992, CAS & JLC, A-9-1, ILLS.

Substratum:

Typha sp., herbaceous debris.

Habitat:

Lentic (lakes).

Distribution:

Canada (Manitoba); U.S.A. (MN, WI)

Pertinent Literature:

Shearer, C.A., J.L. Crane, and W. Chen. 1999. Freshwater Ascomycetes: Ophioceras species. Mycologia 91: 145-156.

Comments:

Additional Pictures

Peridium in face view
Ascus
Asci and hamathecium
Ascospore

Back