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The fauna of Diplura, the two-pronged bristletails (Hexapoda), of the southern Appalachians has received little focused systematic attention. Existing literature suggests the fauna to comprise around a dozen species. Based on a broader DNA barcode-based survey of high elevation litter arthropods in the region, we suggest the fauna to be much richer, with automated species delimitation methods hypothesising as many as 35 species, most highly restricted to single or closely proximate localities. Such a result should not be very surprising for such small, flightless arthropods, although it remains to be seen if other markers or morphology support such high diversity. The region still remains sparsely sampled for these more cryptic elements of the arthropod fauna and much larger numbers of species undoubtedly remain to be discovered. 

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. 

The Pseudoscorpiones fauna of North America is diverse, but in regions like the southern Appalachian Mountains, they are still poorly documented with respect to their species diversity, distributions and ecology. Several families have been reported from these mountains and neighbouring areas. Here we analyse barcoding data of 136 specimens collected in leaf litter, most of them from high-elevation coniferous forest. We used ASAP as a species delimitation method to obtain an estimation of the number of species present in the region. For this and based on interspecific genetic distance values previously reported in Pseudoscorpions, we considered three different genetic Kimura two-parameter distance thresholds (3%/5%/8%), to produce more or less conservative estimates. These distance thresholds resulted in 64/47/27 distinct potential species representing the families Chthoniidae (33/22/12 species) and Neobisiidae (31/25/15) and at least six different genera within them. The diversity pattern seems to be affected by the Asheville Depression, a major biogeographic barrier in this area, with a higher diversity to the west of this geographic feature, particularly within the family Neobisiidae. The absence of representatives from other families amongst our studied samples may be explained by differences in their ecological requirements and occupation of different microhabitats. 

The higher elevations of the southern Appalachian Mountains, U.S.A., host a rich, but little-studied fauna of Proturan hexapods. Here, we publish 117 Proturan barcode sequences from this region, estimated by automated species delimitation methods to represent 72 distinct species, whereas only nine species have previously been reported from the region. Two families, Eosentomidae and Acerentomidae, co-occur at most sampling sites, with as many as five species occurring in sympatry. Most populations exhibit very low haplotype diversity, but divergences amongst populations and amongst closely-related species are very high, a finding common to other phylogeographic studies of Proturans. Though we were unable to identify any of the barcodes to species, they form a useful, if preliminary, glimpse of southern Appalachian Proturan diversity. 

Abstract We are far from knowing all species living on the planet. Understanding biodiversity is demanding and requires time and expertise. Most groups are understudied given problems of identifying and delimiting species. DNA barcoding emerged to overcome some of the difficulties in identifying species. Its limitations derive from incomplete taxonomic knowledge and the lack of comprehensive DNA barcode libraries for so many taxonomic groups. Here, we evaluate how useful barcoding is for identifying arthropods from highly diverse leaf litter communities in the southern Appalachian Mountains (USA). We used 3 reference databases and several automated classification methods on a data set including several arthropod groups. Acari, Araneae, Collembola, Coleoptera, Diptera, and Hymenoptera were well represented, showing different performances across methods and databases. Spiders performed the best, with correct identification rates to species and genus levels of ~50% across databases. Springtails performed poorly, no barcodes were identified to species or genus. Other groups showed poor to mediocre performance, from around 3% (mites) to 20% (beetles) correctly identified barcodes to species, but also with some false identifications. In general, BOLD-based identification offered the best identification results but, in all cases except spiders, performance is poor, with less than a fifth of specimens correctly identified to genus or species. Our results indicate that the soil arthropod fauna is still insufficiently documented, with many species unrepresented in DNA barcode libraries. More effort toward integrative taxonomic characterization is needed to complete our reference libraries before we can rely on DNA barcoding as a universally applicable identification method. 

We describe a second species of Nearctomeris Wesener, 2012, a genus of pill millipede endemic to the southern Appalachians, based on morphological and molecular evidence. The fauna of Glomerida in America is characterized by its low diversity, and Nearctomeris smoky sp. nov. is only the fifth species of the order known from the eastern United States. Our phylogenetic analyses based on COI sequences recover a tentatively monophyletic lineage including both eastern American genera Onomeris Cook, 1896 and Nearctomeris , with a common ancestor in the Late Cretaceous to Mid Eocene and extant diversity within genera dating back to the Miocene. Our results suggest that the observed low diversity of the group in the eastern US is likely caused by extinction events, but it is also possible that new species are yet to be found. We provide new records for Nearctomeris inexpectata Wesener, 2012, Onomeris underwoodi Cook, 1896 and O. australora Hoffman, 1950; the latter is here reported for the first time from South Carolina. We also present DNA barcoding data for all species of Glomerida present in the US that are not yet publicly available. 

Abstract Synthetic studies of arthropod systematics and biodiversity are hindered by overreliance on ‘preferred’ semaphoronts, those life stages (typically adult males) that provide the most taxonomically distinctive characters. However, modern sequence‐based methods for inventory have no such limitations and permit incorporation of any and all representatives of a species. Here, we briefly review the growth and potential of these approaches to faunistic and systematic studies and share results from our own recent work that illustrate the value that other morphs, immature stages and females added to these studies. 

Collembola, commonly known as springtails, are important detritivores, abundant in leaf litter and soil globally. Springtails are wingless hexapods with many North American species having wide distributions ranging from as far as Alaska to Mexico. Here, we analyze the occurrence and intraspecific diversity of springtails with a globular body shape (Symphypleona and Neelipleona), in southern high Appalachia, a significant biodiversity hotspot. The peaks of high Appalachia represent ‘sky islands’ due to their physical isolation, and they host numerous endemic species in other taxa. We surveyed globular Collembola through COI metabarcoding, assessing geographic and genetic diversity across localities and species. Intraspecific diversity in globular Collembola was extremely high, suggesting that considerable cryptic speciation has occurred. While we were able to associate morphospecies with described species in most of the major families in the region (Dicyrtomidae, Katiannidae, Sminthuridae, and Sminthurididae), other families (Neelidae, and Arrhopalitidae) are in more pressing need of taxonomic revision before species identities can be confirmed. Due to poor representation in databases, and high intraspecific variability, no identifications were accomplished through comparison with available DNA barcodes. 

Abstract Developing systematic conservation plans depends on a wealth of information on a region's biodiversity. For ‘dark taxa' such as arthropods, such data are usually very incomplete and in most cases left out from assessments.Sky islands are important and often fragile biodiversity hotspots. Southern Appalachian high‐elevation spruce–fir forests represent a particularly threatened sky‐island ecosystem, hosting numerous endemic and threatened species, but their arthropods remain understudied.Here we use voucher‐based megabarcoding to explore genetic differentiation among leaf‐litter arthropod communities of these highlands, and to examine the extent to which they represent dispersed communities of more or less coherent species, manageable as a distributed unit. We assembled a dataset comprising more than 6000 COI sequences representing diverse arthropod groups to assess species richness and sharing across peaks and ranges. Comparisons were standardised across taxa using automated species delimitation, measuring endemism levels by putative species.Species richness was high, with sites hosting from 86 to 199 litter arthropod species (not including mites or myriapods). Community profiles suggest that around one fourth of these species are unique to single sky islands and more than one third of all species are limited to a particular range. Across major taxa, endemicity was lowest in Araneae, and highest in neglected groups like Isopoda, Pseudoscorpionida, Protura and Diplura.Southern Appalachian sky islands of spruce–fir habitat host significantly distinct leaf‐litter arthropod communities, with high levels of local endemicity. This is the first work to provide such a clear picture of peak and range uniqueness for a taxonomically broad sample. Ensuring the protection of a sizeable fraction of high‐elevation litter species richness will therefore require attention at a relatively fine spatial scale.