Freshwater Ascomycetes - Species Monograph

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Genus	Species	Author
Jahnula	sangamonensis	Shearer & Raja
Class	Order	Family
Dothideomycetes	Jahnulales	Inc. sed.

Genbank ID: 435392 MycoBank ID: 01332

Synonymy:

Description

Habit:

Ascomata on submerged wood.

Ascomata:

Ascomata 468 x 345 µm, globose to obpyriform, reddish brown to black, partially immersed in wood, ostiolate, papillate with subtending brown, septate hyphae ca. 160 x 8 µm that attach the base of the ascomata to the wood.

Peridium:

Peridium 40–44 µm thick, textura-angularis in surface view, in longitudinal section, peridial wall 4–6 cell layers wide; inner layer composed of thin walled, narrow, flattened, elongated, subhyaline cells 11–16 x 4–5 µm, outer layer of large, moderately thick-walled isodiametric, brown cells 14–34 x 15–20 µm.

Beak:

Neck 116–120 x 60–65 µm, central, with reddish brown periphyses; wall of the neck composed of chains of elongated cells diverging away from the ostiolar canal.

Hamathecium:

Pseudoparaphyses 2–3 µm wide, septate, hyaline, anastomosing above the asci.

Ascus:

Asci 164–200 x 15–20 µm (mean= 186 x 16 µm, n= 10), fissitunicate, endoascus extending in water to ca. 270–500 µm in length, cylindrical, with an apical chamber, pedicellate, with eight, overlapping uniseriate ascospores.

Ascospore:

Ascospores 20–28 x 10–12 µm (mean= 24 x 11 µm, n=50), broadly ellipsoidal, one-septate, constricted at the septum, dark brown, with or without minute verruculose ornamentation, multiguttulate, without a sheath.

Sheath:

None observed.

Appendage:

None observed.

Culture:

Colonies on PYG agar, diffuse, dark brown in the center, and hyaline towards the periphery; mycelium septate, thick-walled.

Anamorph:

None observed.

Other info

Type & Location:

USA. ILLINOIS: Piatt County, Robert Allerton Park, Sangamon River 40°0'14''N, 88°38'46''W, UTM 16 360584mE 4429466mN, on submerged, decorticated wood, 25 October 1999, CAS, A-402-1. (ILL). HOLOTYPE.

Other Specimens:

USA. ILLINOIS: Piatt County, Robert Allerton Park, Sangamon River, 40° 13' 47"N, 88° 22' 35"W, UTM 16 382895mE 4454176mN, on submerged, decorticated wood. CAS, A482-1 (ILL). ARKANSAS: Poinsett County, St. Francis River, at public boat landing, 35°31'57''N, 90°25'27''W, UTM Zone 15, 733550mE, 3934959mN, water temperature 8C, pH 5, on submerged, partially decorticated wood, 27 December 1993, CAS and JLC, A188-1.

Substratum:

Decorticated or partially decorticated submerged woody debris.

Habitat:

Lotic.

Distribution:

USA (IL, AR, FL)

Pertinent Literature:

Raja, H.A. and C.A. Shearer. 2006. Jahnula species from North and Central America, including three new species. Mycologia 98: 319–332.; Raja 2007

Comments:

Jahnula sangamonensis is morphologically most similar to J. poonythii K. D. Hyde and S. W. Wong. However, J. sangamonensis differs from J. poonythii in ascomal morphology. The ascomata of J. sangamonensis have a short but prominent neck, the inner wall layer of which has reddish-brown periphyses and the outer wall of which is composed of elongated globose to subglobose cells that diverge outwardly. The asci and ascospores of J. sangamonensis are similar to those of J. poonythii except that the ascospores of J. sangamonensis are shorter than those of J. poonythii. Despite the similarity in size, the asci of the two species are different in that the endoascus of J. sangamonensis extends up to 500 µm length in water. This feature has not been reported for the type species by Hyde and Wong (1999) or by Gonzalez and Chavarria (2005), who reported J. poonythii from Mexico.

Additional Pictures

Broad hyphae
Endoascus apex and kissing bridges of pseudoparaphyses
Periphyses within neck
Broad hyphae
Hamathecium of cellular pseudoparaphyses
Endoascus
Fissitunicate asci
Fissitunicate ascus

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