Les bases de la systématique moderne des Lichens

Abstract

Résumé.-Jusque vers la fin des années soixante, les critères systématiques utilisés en lichéno-logie, notamment dans les flores, étaient restés proches de ceux employés depuis la deuxième moitié du 19ème siècle: morphologie, structure et réactions colorées du thalle et des ascocarpes, structure, couleur et nombre des ascospores, caractères des conidiophores (endo-ou exo-basidiés) et des conidies. Ré-cemment la prise en considération de critères nouveaux, basés sur les recherches les plus récentes de la lichénologie, notamment en cytologie, anatomie et chimie, a bouleversé les bases de la systématique des lichens : appareil apical des asques, paroi des ascospores, ontogénie des ascocarpes et des pycnides, acides lichéniques. Chacun d'eux est analysé et illustré par des exemples empruntés surtout à des travaux français. L'utilisa;on de méthodes mathématiques élaborées, comme l'analyse multivariable, est abordée et le problème de la hiérarchie des caractères discuté.Summary.-Up to the end of the sixties, the systematic criteria used in lichenology, in particular in fior as, staid near those in use in the second half of the 19th century : morphology, structure and color reactions of thallus and ascocarps, structure, color, number of ascospores, conidia and conidiophores characters (i.e : endo-and exobasidiate). Recently, attention brought to new criteria founded upon the most recent researches, especially in cytology, anatomy and chemistry, overthrew the basis of lichen systematic : ascus apical apparatus, ascospore wall, ontogeny of ascocarps and pycnidia, lichen substances. Each of them is analyzed anJ illustrated by examples mainly chosen in french works. Use of elaborated mathematical methods as multivariable analysis is mentioned and the problem of the hierarchy of the characters is discussed.

Species in lichen-forming fungi: balancing between conceptual and practical considerations, and between phenotype and phylogenomics

“…McCabe's (2021) rationale for the term "Linneon" also essentially corresponds to our current understanding of species hypothesis, although in its original sense, Lotsy (1916Lotsy ( , 1925 defined Linneon as morphologically defined species complexes likely to contain a number of distinct lineages, i.e., cryptic speciation. In our LPR approach (see above), a Linneon in a modern sense would (Ainsworth 1976;Jørgensen 2017) : (1) the use of the microscope to assess anatomical characters, in particular ascospores but later on also ultrastructure (Körber 1853;Roux et al 1986); (2) the assessment of the ontogeny as a taxonomically important character (Letrouit-Galinou 1968;Henssen and Jahns 1973;Eriksson 1982;Honegger 1993;Letrouit-Galinou et al 1994;Döring and Lumbsch 1998) ; (3) the study of secondary chemical compounds eventually using chromatographic methods (Zopf 1903;Culberson and Kristinsson 1970;Huneck and Yoshimura 1996); and (4) the advent of molecular phylogeny.…”

Ascomycete Systematics

“…Many types of ascus apex are known, differing in the morphology, structure and differentiation of their wall layers (Baral, 1987a;Hertel and Rambold, 1988;Pietschmann, 1990;Roux et al, 1987;Spooner, 1987;. Some of the more frequently encountered have been recognized for a long time (operculate, bitunicate, annellasces, archeasces; and used in systematics to define major taxa.…”