Freshwater Ascomycetes - Species Monograph

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Genus	Species	Author
Rivulicola	cygnea	Raja & Shearer
Class	Order	Family
Sordariomycetes	Inc. sed.	Inc. sed.

MycoBank ID: 512706

Synonymy:

Description

Habit:

Ascomata on wood scattered to gregarious, venter horizontal to the host surface, subiculate or not.

Ascomata:

Ascomata on wood 470–680 × 140–170 µm, scattered to gregarious, venter horizontal to the host surface, subiculate or not, hyaline to light brown, membranous; venter globose to subglobose, 150–200 × 140-–160 µm, ostiolate, with a long neck.

Peridium:

Peridium 10–12 µm wide, comprising 4-–5 layers of hyaline to light brown, elongated, flattened cells.

Beak:

Neck 240–500 × 30-–40 µm, hyaline, periphysate, covered with short hyaline, protruding hyphae ca. 10-–15 µm long.

Hamathecium:

Hamathecium composed of paraphyses ca. 3 µm wide, simple, septate, filamentous, attached at the base.

Ascus:

Asci 122–155 × 7-–8 µm, numerous, basal, fasciculate, unitunicate, cylindrical, elongating in water, rounded at the apex, apical wall thick, with a non-amyloid apical ring, tapering to a short pedicel at the base, with eight, overlapping, hyaline, uniseriate ascospores.

Ascospore:

Ascospores 20–24 × 6–7 µm, (mean = 22 × 6 µm, n = 40), three septate, ellipsoidal, multiguttulate, forcibly discharged from the asci, surrounded by a mucilaginous sheath ca. 2–3 µm wide at the sides.

Sheath:

Sheath constricted at the first ascospore septum, staining blue in aqueous nigrosin.

Appendage:

Not present.

Culture:

Not obtained.

Anamorph:

Not observed.

Other info

Type & Location:

UNITED STATES. FLORIDA: Apalachicola National Forest, Unnamed Lake east of Lost Lake, 30°21'48"N, 84°22'56"W, water temperature 35C, pH 7, on submerged decorticated wood, 13 July 2004, Huzefa A. Raja and Christopher Brown, F41-1 (HOLOTYPE: ILL40111).

Other Specimens:

Substratum:

Submerged decorticated wood.

Habitat:

Lentic.

Distribution:

USA (FL).

Pertinent Literature:

Raja, H.A., Ferrer, A. and Shearer C.A. 2009.

Comments:

Additional Pictures

Paraphyses stained with aqueous nigrosin
Ascus apex stained with aqueous nigrosin
Ascospore & sheath stained with aqueous nigrosin.
Discharging ascus.
Empty asci.
Endoascus.
Ascospore with sheath.
Ascus stained with aqueous nigrosin.

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