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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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Neogene Corylopsis seeds from eastern Tennessee
Abstract A new fossil species ofCorylopsis(Hamamelidaceae),C. griseaQuirk & Hermsen sp. nov, based on seeds from the early Pliocene Gray Fossil Site (GFS), eastern Tennessee, USA, is described. The assignment of the seeds to Hamamelidaceae, subfamily Hamamelidoideae, is based on the overall size of the seeds, smooth testa, lack of a seed wing, and the presence of a terminal hilar scar. The assignment to the genusCorylopsisis based on seed size as well as the presence of a hilar facet, in addition to the hilar scar. AlthoughCorylopsispersists only in East Asia today, its fossil record indicates that the genus was widespread across the Northern Hemisphere in the past. Prior to its discovery at GFS,Corylopsiswas only known from the Paleogene in North America. The presence ofC. griseaat GFS extends the fossil record ofCorylopsisin North America to the Neogene and reinforces the interpretation of GFS as a forested refugium that provided a relatively moist, equable environment where subtropical to warm temperate plants could persist during a time of cooling and drying in the continental interior of North America. Its presence provides additional evidence for the biogeographic connection between the GFS paleoflora and the modern flora of eastern Asia.
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- Award ID(s):
- 1829376
- PAR ID:
- 10136780
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Systematics and Evolution
- Volume:
- 59
- Issue:
- 3
- ISSN:
- 1674-4918
- Format(s):
- Medium: X Size: p. 611-621
- Size(s):
- p. 611-621
- Sponsoring Org:
- National Science Foundation
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