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Abstract The terrestrial isopod genusLigidiumincludes 58 species from Europe, Asia, and North America. In Eastern North America four species are recognized:L. floridanumandL. mucronatum, known just from their type localities in Florida and Louisiana respectively,L. blueridgensis, endemic to the southern Appalachians, andL. elrodii, widespread from Georgia to Ontario. The genus shows a marked morphological conservatism, and species are differentiated mostly by small morphological differences; it is not always easy to determine if such variability represents inter‐ or intraspecific variation. Here, we explore the diversity ofLigidiumfrom the southern Appalachian Mountains, exploring the congruence of morphologically defined groups with multilocus phylogenetic reconstructions and molecular species delimitation methods. We have studied a total of 130 specimens from 37 localities, mostly from the southern Appalachians, and analysed mtDNA (Cox1) and nuclear (28S, NaK) sequences. Morphologically, we recognized eight morphotypes, most of them assignable to current concepts ofL.elrodiiandL.blueridgensis. Phylogenetic analyses supported the evolutionary independence of all morphotypes, and suggest the existence of 8–9 species, including limited cryptic diversity. Single‐locus delimitation analyses based on mtDNA data suggest the existence of a much higher number of species than the multilocus analyses. The estimated age of the ancestors of sampled lineages indicates a long presence of the genus in eastern North America and old speciation events through the Miocene. Our results indicate a higher diversity than previously thought among theLigidiumpopulations present in the southern Appalachian Mountains, with several species to be described.
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Species delimitation and invasion history of the balsam woolly adelgid, Adelges ( Dreyfusia ) piceae (Hemiptera: Aphidoidea: Adelgidae), species complex
Abstract TheAdelges(Dreyfusia)piceae(Ratzeburg) species complex is a taxonomically unstable group of six species. Three of the species are cyclically parthenogenetic [Ad.nordmannianae(Eckstein),Ad.prelli(Grossmann), andAd.merkeri(Eichhorn)] and three are obligately asexual [Ad.piceae,Ad.schneideri(Börner), andAd.nebrodensis(Binazzi & Covassi)]. Some species are high‐impact pests of fir (Abies) trees, so stable species names are needed to communicate effectively about management. Therefore, to refine species delimitation, guided by a reconstruction of their biogeographic history, we genotyped adelgids from Europe, North America, and the Caucasus Mountains region with 19 microsatellite loci, sequenced the COI DNA barcoding region, and compared morphology. Discriminant analysis of principal components of microsatellite genotypes revealed four distinct genetic clusters. Two clusters were morphologically consistent withAd.nordmannianae. One of these clusters consisted of samples from the Caucasus Mountains and northern Turkey, and the other included samples from this region as well as from Europe and North America, whereAd.nordmannianaeis invasive. A third cluster was morphologically consistent withAd.piceae, and included individuals from Europe, where it is native, and North America, where it is invasive. In North America, the majority ofAd.piceaeindividuals were assigned to two geographically widespread clones, suggesting multiple introductions. The fourth cluster included individuals morphologically consistent withAd.prelliorAd.merkeri. However, based on genetic assignments, hybrid simulations, and approximate Bayesian computation, we find it likely that these are contemporary hybrids betweenAd.nordmannianaeandAd.piceaethat arose independently in Europe and North America, so we propose thatAd.prelliandAd.merkeriare invalid. Finally, we synonymiseAd.schneideri(syn.n.)withAd.nordmannianaeand designateAd.nebrodensisas subspeciesAd.piceae nebrodensis(stat.n.). Our revised taxonomy therefore recognises two species:Ad.nordmannianaeandAd.piceae, which we estimate to have diverged recently, during one of the last two interglacial periods. Finally, we comment on this species complex being in the midst of transition between sexual and asexual reproduction, a pattern that is probably common in Adelgidae.
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- Award ID(s):
- 1655182
- PAR ID:
- 10381612
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Systematic Entomology
- Volume:
- 46
- Issue:
- 1
- ISSN:
- 0307-6970
- Format(s):
- Medium: X Size: p. 186-204
- Size(s):
- p. 186-204
- Sponsoring Org:
- National Science Foundation
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