Stigmidium epixanthum Hafellner

Data Set Maintenance: Data set compiled. Data set author(s): Cáceres M. Data set not revised; not to be published after submission.

Nomenclature: Current taxonomic status: accepted. Taxonomic rank: species. Stigmidium. Genus incertae sedis: Stigmidium; of unknown placement (incertae sedis).

Taxonomic Literature: Hafellner J., Triebel D., Ryan B. D. & Nash III, T. H., Mycotaxon 84: 293-329 [317-319] (2002).

Biogeography: Northern hemispheric. Continent: Africa, Australasia, Northern America, and Southern America. Region(s): Macaronesia (Cape Verde – Canary Islands – Madeira – Azores), Western Tropical Africa, Australia, South-western U.S.A., South-Central U.S.A., North and Central Mexico, and Northern South America (Guyana). Country or state(s): Canary Islands (Spain), Madeira (Portugal), and Angola; Northern Territory (Australia) and Queensland (Australia); Arizona (USA), Utah (USA), New Mexico (USA), and Northwestern Mexico (Mexico); Venezuela.

Ecology: Biotroph; lichenicolous, endosubstratic; growing on non-calciferous rock or calciferous rock. Host or Phorophyte Taxonomy: Acarospora heufleriana, A. lavicola, A. radicata, A. xanthophana, A. spec. div.

Lichen Photobionts: Primary photobiont absent.

Thallus: Indistinct.

Medulla: Iodine reaction in Lugol's solution negative.

Reproduction Strategy: With sexual (and possible asexual) stages. Ascocarps: Perithecioid, globose or obpyriform, forming inside the thallus or mycelium of the host, within the ascocarp margin of the host or within the ascocarp disks of the host, soon sessile, 120-180 µm wide, 100-140 µm high, with a black surface. Wall: Not carbonized, dimidiate. Margin: Smooth, black, inhomogenously pigmented, 30 µm wide; external filaments absent. Exciple: Carbonized (only the outer layer from ascomata wall), dark brown. Periphyses: Absent. Hymenium: Iodine reaction: Lugol’s negative, not hemiamyloid. Interascal Hyphae: Present, distinctly branched, distinctly anastomosed. Hypothecium: White or pale brown.

Asci: Clavate (calvate to saccate), 40-55 µm long, 12-15 µm wide; tholus not amyloid; ocular chamber present; dehiscence bitunicate (fissitunicate); exoascus not amyloid, not hemiamyloid; ascoplasm not dextrinoid.

Ascospores: Not uniseriate, c. 8 per ascus, spores 8 per ascus, ellipsoid, 13-14.4-16 µm long, 5-5.9-7 µm wide, obtuse; septa present, transversally septate, 1-transversally septate; lumina apically enlarged, constricted at the centre; wall thin, remaining hyaline, hyaline, in Lugol's Solution negative, wall not ornamented.

Conidiomata: Absent resp. not observed.

Secondary Metabolites: Not detected.

(report generated 04.Okt.2007)