Freshwater Ascomycetes - Species Monograph

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Genus	Species	Author
Jahnula	aquatica	Jahnula aquatica (Plöttner and Kirschst.) Kirschst., Ann. Mycol. 34: 196. 1936
Class	Order	Family
Dothideomycetes	Jahnulales	Inc. sed.

Genbank ID: 435389 MycoBank ID: 257114

Synonymy:

≡ Amphisphaeria aquatica Plöttner and Kirschst., Verh. Bot. Ver. Prov. Brandenb. 48: 52. 1906.
≡ Melanopsamma aquatica (Plöttner and Kirschst.) Kirschst., Krypt. Fl. Brandenb. 7: 226. 1911.

Description

Habit:

On submerged wood.

Ascomata:

Ascomata 345–380 x 265–330 µm, hyaline when young, becoming translucent black with age, membranous, globose to subglobose, ostiolate, papillate, superficial to partially immersed in wood, scattered, attached to adjacent ascomata by broad, brown, superficial, stoloniferous hyphae

Peridium:

Peridium 20–30 µm wide, of textura angularis in surface view, in longitudinal section peridial wall 3–4 cell layers wide, composed of an outermost layer of large, moderately thick-walled brown cells, and an inner layer of elongated, flattened, thin-walled hyaline cells

Beak:

Neck 60–95 x 74–80 µm, periphysate; periphyses short, hyaline

Hamathecium:

Pseudoparaphyses septate, narrow, 1.5–2 µm wide, hyaline, filiform, branched and anastomosing above the asci

Ascus:

Asci 105–215 x 10–20 µm, fissitunicate, cylindrical, pedicellate, with an apical chamber and eight, overlapping uniseriate ascospores

Ascospore:

Ascospores 30–40 x 10–12 µm, brown to dark brown, ellipsoidal-fusiform, one-septate, constricted at the septum, upper cell broader than basal cell, multiguttulate,

Sheath:

None observed.

Appendage:

None observed.

Culture:

Colonies on peptone yeast extract glucose agar growing slowly, dark brown to black, effuse; hyphae thick-walled, septate and constricted at the septa; cells of the hyphae cylindrical to subglobose

Anamorph:

None observed

Other info

Type & Location:

Jahnula aquatica (Plöttner and Kirschst.) Kirschst., Ann. Mycol. 34: 196. 1936. Germany, Havelland, Hohennauener See, on Salix wood in water in a ditch, 12 June 1904, W. Kirschstein (B, lectotype, selected by Hawksworth 1984)

Other Specimens:

USA. ILLINOIS: Salt Fork Association Lake (SFA Lake), a man- made private lake located about 16 miles east of Urbana, 40°05'00"N, 87°48'50"W, UTM 16 435946E, 4992530N, water temperature 16.5 C, pH 7, on submerged, decorticated wood, 15 Oct 2002, HAR, R68-1. TENNESSEE: Hamilton County, Tennessee River, Tennessee River Gorge Trust, 15 miles west of Chattanooga, 35°08'95''N, 85°39'97''W, UTM 16 620500mE, 3891557mN, water temperature 18 C, pH 6.5, on submerged, decorticated wood, 29 March 2005, HAR, JLC, and ANM, F75-1; Great Smoky Mountains National Park, Cades Cove, 11 mile loop, Abrams Creek, 35°35'36"N, 83°50' 42"W, UTM Zone 17 242232mE, 3942559mN, water temperature 17 C, pH 5, on soft, decorticated, submerged wood, 21 June 2005, HAR and ANM, R68-2.

Substratum:

Submerged wood

Habitat:

Lentic and lotic freshwater habitats

Distribution:

Germany, Hong Kong, South Africa, Thailand, USA (IL, TN)

Pertinent Literature:

1. Raja, H.A. and C.A. Shearer. 2006. Jahnula species from North and Central America, including three new species. Mycologia 98: 319–332. 2. Hyde, K.D. and S.W. Wong. 1999. Tropical Australian Freshwater Fungi. XV The ascomycete genus Jahnula, with five new species and one new combination. Nova Hedwigia 68: 489–509. 3. Hawksworth, D.L. 1984. Observations on Jahnula Kirschst., a remarkable aquatic pyrenomycete. Sydowia 37: 43–46.

Comments:

Additional Pictures

Ascoma in surface view with broad attached hyphae
Longitudinal section of ascoma
Longitudinal section of ascoma
Discharged ascus
Ascus apices

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