Podosphaera fusca (Fr.) U. Braun & N. Shishkoff

Data Set Maintenance: Data set compiled and standard item. Data set author(s): Kainz C. Data set revised.

Nomenclature: Current taxonomic status: accepted. Taxonomic rank: species. Synonyms: Sphaerotheca fusca (Fr.) S. Blumer; Erysiphaceae Tul. & C. Tul.; Erysiphales.

Type Information: Basionym: Erysiphe fusca Fr.

Taxonomic Literature: Taxonomic notes: +appressoria indistinct, sometimes slightly nipple-

shaped;
+conidiophores foot-cells cylindric, followed by 1-3
shorter
cells;
+ascocarp outer wall cells conspicuous, large,
irregularly
shaped, (10-)15-45(-55) µm diam.;. Braun U., Beih. Nova Hedwigia 89: 1-700 [144-147] (1987); Kiss L., Szentiványi O., New Disease Reports 2 (August 2000 - January 2001).

Biogeography: Nearly cosmopolitan.

Ecology: Biotroph; phytopathogenic; growing on stems and leaves, amphigenous (mycelium at first hyaline, later gradually turning to brown, hardly separable from the cleistothecial appendages; groups of ascocarps, appendages and coloured hyphae often forming dark patches on the leaves or stems). Host or Phorophyte Taxonomy: Acanthaceae, Bignoniaceae, Campanulaceae, Compositae, Cucurbitaceae, Labiatae, Leguminosae-Papilionoideae, Polemoniaceae, Scrophulariaceae, Solanaceae, and Valerianaceae.

Reproduction Strategy: With sexual (and possible asexual) stages. Ascocarps: Cleistothecioid, orbicular, forming independently from the host thallus or mycelium, scattered and gregarious, (.06)-.07-.1-(.12) mm in diam.. Margin: External filaments present; mycelioid (rather coarse, length variable, width irregular), .5-4 µm long, 4-10-(12) µm in diameter, hyaline and pigmented (brown throughout when mature, long appendages often paler or hyaline in the upper half), few (mostly few, less than 10, seldom more), up to 10 per mm², growing all across the lower half of the ascocarp (mostly; 4: occasionally) and on the upper half of the ascocarp, smooth and rough, thin, not ramified and ramified (occasionally), irregularly not branched, septate.

Asci: 1 asci per ascocarp, sub-globose, broadly clavate, or clavate, not stipitate or rarely indistinctly stipitate, 50-80-(100) µm long, 40-70-(80) µm wide; dehiscence unitunicate.

Ascospores: c. 8 (development of the ascospores usually fairly late, asci mostly immature) per ascus, spores 6-8 per ascus, subglobose, broadly ellipsoid, or ovoid, 13-20-(24) µm long, (11)-12.5-16-(18) µm wide; septa absent; wall thin, remaining hyaline, hyaline, not ornamented.

Conidiomata: Present; hyphomycetous (conidiophores erect foot cells cylindric, followed by 1-3 shorter cells).

Conidiophores: Oidium-type; not branched; basal cells (25)-40-80 µm long, 9-14.5 µm wide. Conidium Formation: Conidiogenous cells in chains. Conidia: Ellipsoid, ovoid, or doliiform; macroconidial, not branched, 24-45-(50) µm long, 14-22-(26) µm wide; aseptate; with distintly visible fibrosin body fibrosin bodies.

(report generated 04.Okt.2007)