Diamorpha

Abstract: Most of the Piedmont Physiographic Province of the southeastern United States is covered with mixed mesophytic forest of oaks, hickories, and pines. Within this “sea”, however, are “islands” of exposed granite and gneiss. A characteristic, and largely endemic, assemblage of plants has adapted to the environmental extremes that bare rock provides by strongly altering their morphology, physiology, and life history. With respect to their reproductive ecology, however, these plants appear very similar to their congeners and to the Piedmont flora as a whole. Except for ant-pollinated Diamorpha smallii, most species show the expected range of pollen vectors, including wind, bees, flies, butterflies, moths and one species of hummingbird. Fruit and/or seed dispersal appears to be highly localised and effected primarily by wind and water. If anything, most species appear to possess adaptations against long-distance dispersal, which would carry propagules into the inhospitable matrix of oak-hickory-pine forest. Mating systems are variable, including examples of both self-compatible and self-incompatible taxa. Consistent with the expectation of low gene flow between populations on isolated outcrops, genetic data show strong differentiation and suggest the potential for genetic drift and/or natural selection to result in divergence. Some of the endemic species on granite outcrops have originated by allopolyploidy, whereas others appear to represent products of more gradual divergence in geographical isolation. There is reason to believe that some weedy species of early successful sites were originally restricted to granite outcrops and spread more recently to sites disturbed by human activities.

Abstract: Sewanee: The University of the South, located in Franklin County, Tennessee, is a 5,263 ha site that encompasses a variety of plateau and cove habitats on the southern Cumberland Plateau in southeastern Tennessee. The vascular flora of the University of the South was documented from 1948–2015 and comprises 1,118 species and lesser taxa in 553 genera and 150 families. We documented 229 exotic taxa, 20.5% of the flora. This flora contains six state records, 74 Franklin County records, and two potential new species. Eighteen taxa are listed as protected either at the state or federal level, including the federally listed endangered Clematis morefieldii and state listed endangered Diamorpha smallii, Silphium brachiatum, and Symphyotrichum pratense. When compared to the five other published floras for the southern Cumberland Plateau in Tennessee, the University of the South flora is the most diverse, capturing 69% of the total taxa at the species level for the region. The high diversity of plant spec...

Abstract: The oribatid mite Zygoribatula colemani sp. nov. (Oribatulidae) is described and illustrated based on adults collected from shallow soils in depression pits found in granitic outcrops of the Piedmont Plateau in Georgia (USA). By definition, members of Zygoribatula always possess a translamella on the prodorsum, the only feature distinguishing this genus from Oribatula. But Z. colemani shows a full range of variation, from having the translamella well developed to entirely absent; this brings the distinction of these genera into question and points out the need for a careful revision of generic concepts in Oribatulidae. Depending on the specimens examined, Z. colemani could be placed in either genus, but we tentatively include it in Zygoribatula, since in some specimens the translamella is complete and well delineated. A tentative diagnostic key to differentiate the species of Zygoribatula previously reported in the USA is included.