Genus delimitation, biogeography and diversification of Choristoneura Lederer (Lepidoptera: Tortricidae) based on molecular evidence
Résumé
Widely known for pest species that include major modulators of temperate
forests, the genus Choristoneura is part of the species-rich tribe Archipini of leafroller
moths (Tortricidae). Delimitation of the genus has remained unresolved because no
phylogeny has included species endemic to Africa and studies have often omitted the
type species of the genus. Further taxonomic confusion has been generated by the
transfer of Archips occidentalis (Walsingham) to Choristoneura, creating a homonym
with Choristoneura occidentalis Freeman, an important defoliator of North American
forests. To define the limits of the genus, we reconstructed a phylogeny using DNA
sequences for mitochondrial cytochrome oxidase subunit I and nuclear ribosomal 28S
genes. Our ingroup included 23 Choristoneura species-level taxa, complemented by a
large sample of outgroups comprising 82 species of Archipini and other Tortricidae.
We generated a time-calibrated tree using fossil and secondary calibrations and we
inferred biogeographic and diversification processes in Choristoneura. Our analysis
recovered the genus as polyphyletic, with Archips occidentalis, Choristoneura simonyi
and Choristoneura evanidana excluded from the main clade. Based on the recovered
phylogenies and a redefinition, we restrict Choristoneura primarily to species with a
northern hemisphere distribution. Our analysis supports A. occidentalis as the sister
group of Cacoecimorpha pronubana, C. simonyi as the sister of ‘Xenotemna’ pallorana,
and C. evanidana as the sister of Archips purpurana. A new combination is proposed:
Archips evanidana comb.n.; the availability of ‘Xenotemna’ as a valid name is discussed
and A. occidentalis is considered as an orphaned name within the Archipini. We
found support for a Holarctic origin of Choristoneura about 23 Ma, followed by early
divergence in the Palearctic region. The main divergence occurred at 16Ma, with one
clade in the Nearctic and another in the Palearctic. Subsequent cladogenetic events
were synchronous and related to herbivorous specialization, with each clade divided
into coniferophagous and polyphagous lineages. Their specialization as conifer feeders
temporally matched the expansion of boreal forest during the Miocene.