Freshwater Ascomycetes - Species Monograph

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

Genus	Species	Author
Gnomonia	petiolorum	(Schw. :Fries) Cooke, Grevillea 7: 54. 1878.
Class	Order	Family
Sordariomycetes	Diaporthales	Valsaceae

Synonymy:

≡ Sphaeria petiolorum Schw. : Fries, Syst. Mycol. 2: 518. 1823.
≡ Gnomoniella amoena var. petiolorum (Schw.) Sacc., Syll. Fung. 1: 414. 1882.

Description

Habit:

Immersed on submerged, decomposed Acer rubrum leaves.

Ascomata:

Ascomata 630–904 x 310–340 µm, immersed, scattered, mostly globose or depressed globose, membranous, brown, occurring on petioles near major veins and at the base of the leaf blade.

Peridium:

Peridium 22–30 µm thick, 4–5 layers wide, composed of two distinct cell layers; outer cell layer pseudoparenchymatic and much broader and less compressed than inner wall layers, 10–16 x 6–10 µm; inner cell layers of polygonal, fusoid, compressed, thin walled cells, 12–28 x 3–6 µm; cells in surface view pseudoparenchymatic 16–50 x12–24 µm.

Beak:

Beak 416–744 x 24–40 µm, protruding from the epidermis, with crystalline amorphous material at the base, periphysate, central, with distinct cells of textura porrecta in surface view, with hyaline mass at the tip, 24–31 x 32–39 µm, containing hyphal-like filaments that are hyaline

Hamathecium:

Paraphyses absent.

Ascus:

Asci 30–36 x 6–8 µm, broadly clavate, becoming slightly narrower or cylindrical or sometimes truncate at the apex, with tapered fusoid stipe, extremely abundant, loosening from subhymenium and lying freely in the ascomal cavity, unitunicate, provided with a refractive apical apparatus, MLZ-, with 8 ascospores.

Ascospore:

Ascospores (11-) 12–14 x 2–2.5 µm, hyaline, ellipsoid to broadly fusoid, with a single median septum, mostly straight, at times allantoid, mostly in single to occasionally two overlapping fascicles in ascus, with bipolar appendages 4–6 µm long.

Sheath:

Absent.

Appendage:

Hyaline bipolar appendages 4–6 µm long.

Culture:

Anamorph:

Other info

Type & Location:

Other Specimens:

Substratum:

1. Submerged, decomposed Acer rubrum leaves.

Habitat:

1. Lotic habitats.

Distribution:

1. USA (WI)

Pertinent Literature:

1. Fallah & Shearer 2001.

Comments:

1. It is likely that G. petiolorum is carried into the aquatic habitat on leaves from riparian vegetation.

Additional Pictures

Back