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Most cave-obligate species (troglobionts) have small ranges due to limited dispersal ability and the isolated nature of cave habitats. The troglobiontic linyphiid spiderPhanetta subterranea(Emerton, 1875), the only member of its genus, is a notable exception to this pattern; it has been reported from more counties and caves than any other troglobiont in North America. As many troglobionts exhibit significant genetic differentiation between populations over even small geographic distances, it has been hypothesized thatPhanettamay comprise multiple, genetically distinct lineages. To test this hypothesis, we examined genetic diversity inPhanettaacross its range at the mitochondrial cytochrome c oxidase subunit I gene for 47 individuals from 40 caves, distributed across seven states and 37 counties. We found limited genetic differentiation across the species’ range with haplotypes shared by individuals collected up to 600 km apart. Intraspecific nucleotide diversity was 0.006 +/- 0.005 (mean +/- SD), and the maximum genetic p-distance observed between any two individuals was 0.022. These values are within the typical range observed for other spider species. Thus, we found no evidence of cryptic genetic diversity inPhanetta. Our observation of low genetic diversity across such a broad distribution raises the question of how these troglobiontic spiders have managed to disperse so widely. 

This revision is based on sampling efforts over the past three decades in the southern Appalachian Mountains which have providedNesticus(Araneae, Nesticidae) collections of approximately 2100 adult specimens from more than 475 unique collecting events. Using a “morphology first” framework we examined recently collected specimens plus museum material to formulate morphology-based species hypotheses for putative new taxa (discovery phase). Using sequence capture of nuclear ultraconserved elements (UCEs) we analyzed 801 nuclear loci to validate new (and prior) morphology-based species hypotheses (validation phase) and reconstructed a robust backbone phylogeny including all described and new species. Sanger sequencing and UCE-bycatch were also used to gather mitochondrial data for more than 240 specimens. Based on our integrative taxonomic framework ten newNesticusspecies are herein described, includingN. binfordaesp. nov.,N. bondisp. nov.,N. caneisp. nov.,N. cherokeensissp. nov.,N. dellingerisp. nov.,N. dykemanaesp. nov.,N. jemisinaesp. nov.,N. lowderisp. nov.,N. roanensissp. nov., andN. templetonisp. nov.Previously unknown males are also described forN. bishopiGertsch, 1984,N. crosbyiGertsch, 1984, andN. silvanusGertsch, 1984, as well as the previously unknown female forN. mimusGertsch, 1984. Based on combined evidenceN. cooperiGertsch, 1984 is placed in synonymy withN. reclususGertsch, 1984. Overall, the montane radiation of AppalachianNesticusreveals a general lack of species sympatry and compelling biogeographic patterns. Several regionalNesticustaxa are rare, microendemic habitat specialists that deserve conservation attention and detailed future monitoring as conservation sentinels.