| Davydov, E; Peršoh, D; Rambold, G: Umbilicariaceae (Lichenized Ascomycota) – Trait evolution and a new generic concept, Taxon, 66(6), 1282–1303 (2017), doi:10.12705/666.2 | |
| Abstract: To reconstruct hypotheses on the evolution of Umbilicariaceae, 644 sequences from three independent DNA regions were used, 433 of which were newly produced. The study includes a representative fraction (presumably about 80%) of the known species diversity of the Umbilicariaceae s.str. and is based on the phylograms obtained using maximum likelihood and a Bayesian phylogenetic inference framework. The analyses resulted in the recognition of eight well-supported clades, delimited by a combination of morphological and chemical features. None of the previous classifications within Umbilicariaceae s.str. were supported by the phylogenetic analyses. The distribution of the diagnostic morphological and chemical traits against the molecular phylogenetic topology revealed the following patterns of evolution: (1) Rhizinomorphs were gained at least four times independently and are lacking in most clades grouping in the proximity of Lasallia. (2) Asexual reproductive structures, i.e., thalloconidia and lichenized dispersal units, appear more or less mutually exclusive, being restricted to different clades. Two major ontogenetic types of thalloconidial development (thallobred versus rhizinobred) exist, reflecting their non-homologous origin. Both types of thalloconidial formation were gained multiple times. (3) “Gyrodisc-omphalodisc” apothecia are plesiomorphic in Umbilicariaceae. The apothecial type is a relatively variable trait, because the main types of apothecia switched at least six times in evolution. Multiple evolutionary changes from the gyrodiscs to leiodiscs, by reduction of carbonized hymenial structures, seem likely. (4) Ascospore characters, such as spore number per ascus, spore size, and septation type and degree are strongly correlated. Eight non-septate small ascospores per ascus represent a plesiomorphic trait. The results indicate parallel evolutionary trends from “gyrodisc-omphalodisc” to leiodisc apothecia, from octospory to mono- or bispory and from unicellular to multicellular-muriform ascospores. The other types of apothecia and ascospores evolved multiple times. This suggests that the concept of Umbilicariaceae s.str. has to be refined. The new classification includes eight subgenera in the only genus Umbilicaria: subg. Actinogyra (type: U. muehlenbergii), subg. Agyrophora (type: A. atropruinosa), subg. Floccularia subg. nov. (type: U. deusta), subg. Gyrophora (type: U. vellea), subg. Iwatakia subg. nov. (type: U. esculenta), subg. Lasallia (type: L. pustulata), subg. Umbilicaria (type: U. hyperborea), and subg. Umbilicariopsis subg. nov. (type: Umbilicaria polyrhiza). Furthermore, four new combinations are proposed: Umbilicaria daliensis comb. nov., U. hispanica comb. nov., U. sinorientalis comb. nov., U. xizangensis comb. nov. |
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