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2. Taxonomic part 46
conspicuous, usually clearly separated from proper exciple, rarely not clearly separated
(Topeliopsis-type), up to c. 20-45 µm long, predominantly clear, but sometimes also
interspersed. True columella or columellar structures absent. Epihymenium (moderately) thin
to (very) thick, predominantly hyaline, rarely pale yellowish or ±brownish, with fine to coarse
granules.
Asci 1-8-spored, non-amyloid, clavate, ascus walls unthickened (fide Frisch 2006
distinctly thickened ascus walls in C. eitenii and C. zahlbruckneri), tholus predominantly
present, in C. lamellifera absent, in younger stages predominantly thin to thick, becoming thin
or not visible at maturity, rarely remaining distinctly thickened throughout development.
Ascospores uni- to quadriseriate, very small to very large, 9-190 x 2-50 µm, predominantly
transversely septate to more rarely (eu)muriform. Cell walls thin to moderately thick, more
rarely distinctly thick, smooth to rarely crenate, in muriform ascospores endospore thin to
moderately thick, non-halonate to distinctly halonate, especially in younger stages, thin to
very thick, sometimes ±distinctly irregular. Ascospores hyaline to sometimes slightly
yellowish or grayish at late maturity, rarely distinctly brown, non-amyloid to strongly
amyloid. Oblong to ellipsoid or fusi- to claviform, rarely bacillar to bacillar-fusiform with
roundish to acute ends, straight to more rarely ±bent, with 3-35 loci in transversely septate
ascospores, with 8-18 x 1-6 or multiple loci in muriform ascospores, solitary end cells
hemispherical to conical, loci small to large, roundish to angular, ±irregular, subglobose,
oblong or lentiform, more rarely ± cuboid, transverse septae thin to ±distinctly thickened,
regular to irregular, in densely muriform ascospores often distinct only younger stages,
becoming indistinct and vanishing with age.
PYCNIDIA – Only found in C. lordhowensis, see there for description.
CHEMISTRY – Secondary compounds present or absent, if present, then predominantly of
the stictic acid, rarely the protocetraric acid chemosydrome.
ECOLOGY AND DISTRIBUTION – The Chapsa species in Australia predominantly occur on
tree bark, rarely on dead wood, mosses, soil, siliceous rock, debris or on leaves in altitudes
ranging between sea level and 1250 m. The greatest diversity of species is found in
rainforests, rarely wet sclerophyll forests and monsoon forests, in tropical to sub-tropical
climates of north-western Northern Territory, Pacific Queensland and northern New South
Wales and on Lord Howe Island. Fewer species were found in rainforests, rarely wet
sclerophyll forests and (sub)alpine heathlands, in warm- to cool-temperate climates in Pacific
southern New South Wales, in southern Victoria and on Tasmania. At present state of
knowledge, amongst the 19 species known in Australia, seven are endemic (C. halei, C.
lassae, C. lordhowensis, C. megaphlyctidioides, C. niveocarpa, C. pulchra, C. tibellii), four
are subantarctic (C. asteliae, C. lamellifera, C. megalophthalma, C. minor), two are
paleotropical to paleotemperate (C. indica, C. subpatens) and six are pansubtropical to
pantropical (C. alborosella, C. astroidea, C. leprieurii, C. leprocarpa, C. phlyctidioides, C.
platycarpa).
NOTES – This genus was recently resurrected (Frisch, 2006) to accommodate taxa formerly
grouped in Chroodiscus and Thelotrema, here in particular the members of the ‘Thelotrema
platycarpum-group’ (Salisbury, 1972b) and Thelotrema subgen. Asteristion (Matsumoto,
2000). The genus name was introduced by Massalongo in 1860 and was neglected ever since.
The taxa in Chapsa are characterized by a predominantly corticolous, thin thallus, typically
large, chroodiscoid ascomata with fused to indistinctly free proper exciple (except C.
platycarpa, which has a distinctly free proper exciple), un-branched, discoid to rarely slightly
cupular hymenia and the presence of lateral paraphyses. The most similar genera are