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Over 300 non-accidental animal species are recorded from subterranean (cave and groundwater) habitats in the Upper Mississippi River Valley (UMV) region. Most of these are trogloxenes or troglophiles and these are not restricted to nor morphologically specialized for subterranean habitats. Conspicuous examples are bats, fish, moths, camel crickets, and many kinds of flies. A rich fauna of some 56 species are seemingly obligatory inhabitants of subterranean habitats. Twenty-two species of these are terrestrial, termed troglobites, and 34 species are aquatic, called stygobites. The troglobites include pseudoscorpions, mites, spiders, millipeds, collembolans, bristletails, and a beetle. These generally have smaller distributional ranges, but some do occur in states outside of the UMV region. The stygobites include flatworms, snails, amphipods, and isopods. These generally have larger distributional ranges and most occur in southwestern Illinois, which was near to, but not covered by Pleistocene glacial ice. A subset of stygobites are known only from groundwaters in non-cavernous glaciated regions. Among the vertebrates, ten species of trogloxenic cave-inhabiting bats are known from the UMV. Other vertebrates include the Spring cavefish (Forbesichthys agassizii), three species of plethodontid salamanders, one frog, and a bird that nests in cave entrances. Included among the mammals, other than bats, are the White-footed mouse (Peromyscus leucopus), Eastern woodrat Neotoma floridana, and Raccoon (Procyon lotor).

This description of Chaetaspis attenuatus, new species, from two caves in northern Arkansas brings the total species assigned to the genus to six. Chaetaspis attenuatus occurs approximately 100 kilometers to the southeast of its sister species C. aleyorum that occurs in southwestern Missouri.

Mexistenasellus floridensis sp. n. is described from Hole in Wall Cave, Jackson County, Florida. The discovery of this unique isopod nearly doubles the range of the Family Stenasellidae in North America, which was previously known from Oaxaca, Mexico to southern Texas, USA. This is the first stenasellid reported swimming in the water column of a cave, a curious finding for an isopod that belongs to a group that is generally more adapted to inhabiting interstitial spaces. Mexistenasellus floridensis occurs syntopically with the subterranean asellid Caecidotea putea. Both species have been observed swimming in the water column, although neither has apparent anatomical adaptations for swimming as compared to the natatory pereopods of Remasellus parvus, an asellid that occurs in caves in Alachua, Madison and Wakulla counties, Florida.

More than 85 species of cave-obligate (troglobiotic) millipede have been described from North America. Understanding the patterns and processes that determine their distribution in this region is an area of recent research. Here, we present the first molecular phylogeographic study of troglobiotic millipedes. Millipedes of the genus Tetracion Hoffman, 1956 (Callipodida: Abacionidae) inhabit caves on the Cumberland Plateau in Tennessee and Alabama, a global hotspot for cave biodiversity. Three species have been described: T. jonesi Hoffman, 1956, T. antraeum Hoffman, 1956, and T. tennesseensis Causey, 1959. To examine genetic divergence within and between species of Tetracion we sequenced part of the mitochondrial cytochrome oxidase 1 gene from 53 individuals from eleven caves across the range of T. tennesseensis and in the northern part of the range of T. jonesi. We found: (1) little variation within species (six haplotypes in T. tennesseensis and four haplotypes in T. jonesi, with a maximum of 1.4% intraspecific divergence between haplotypes), (2) that gene flow between caves is limited (7 of 10 haplotypes were restricted to a single cave, and F ST > 0.80 and P < 0.05 for fifteen of eighteen comparisons between caves), and (3) significant genetic divergence between species (8.8% between T. tennesseensis and T. jonesi). Our results are consistent with previous morphology-based species definitions showing T. tennesseensis and T. jonesi belonging to distinct taxa. Our research contributes to the growing body of phylogeographic information about cave species on the Cumberland Plateau, and provides a point of comparison for future studies of troglobionts and millipedes.

Five species of subterranean asellid are known from Maryland: Caecidotea pricei, C. franzi, C. holsingeri, C. mausi and C. vandeli. Caecidotea nordeni, n. sp. is a subterranean species described from Washington Co., Maryland and assigned to the hobbsi Group. A new locality for C. franzi in Kentucky is presented. This species was previously known from two caves in Maryland and Pennsylvania. The newly discovered population represents a range extension of over 400 km. The male pleopod 2 morphology of specimens from a Maryland population of the subterranean asellid C. holsingeri is compared with populations from three caves in West Virginia. The range of C. holsingeri extends from eastern West Virginia and adjacent Virginia to Garrett Co., Maryland.

Two asellid isopods were described from Nickajack Cave, Tennessee: Caecidotea nickajackensis Packard (in Cope & Packard 1881) and Caecidotea richardsonae Hay (1901). It was long assumed that only one species was actually present in the cave, but Packard's type specimens were lost and the inundation of the cave by a Tennessee Valley Authority impoundment in 1967 eliminated the possibility of collecting additional specimens. Further confusion was created when specimens from Metcalf, Georgia were erroneously identified by Richardson as C. nickajackensis, then redescribed as that species by Steeves (1964). Examination of Hay's type specimens as well as a 1967 collection from Nickajack Cave now confirms the presence of two taxa. The name Caecidotea nickajackensis is applied to the Nickajack Cave asellid represented in the 1967 collection, whereas Caecidotea richardsonae is applied to the species represented in Hay's collection. Caecidotea catachaetus (Fleming & Steeves) is considered a junior synonym ...

A survey of cave and spring fauna in Oklahoma resulted in the discovery of Caecidotea mackini, new species, which is described from specimens collected in Long's Cave, Delaware County. Within the hobbsi group of the genus Caecidotea, C. mackini belongs to a subset of nine species termed the tridentata assemblage. All nine are subterranean, but several retain vestigial eyes or pigmentation. Correlated with zoogeographic and climatic evidence, the invasion of groundwaters by an epigean progenitor during the middle to late Tertiary is suggested. Besides C. mackini, new records for C. macropropoda, C. acuticarpa, C. stiladactyla, C. steevesi, C. ancyla, C. antricola, C. adenta, and C. simulator expand the known ranges of these cryptic species. With the recognition of two patterns of fourth pleopod morphology in C. acuticarpa, the species specificity of this character has become questionable. Although previously used to differentiate C. simulator and C. steevesi, further splitting or synonymy based on...

The world's obligate cave-dwelling fauna holds considerable promise for biogeographic analysis because it represents a large number of independent evolutionary experiments in isolation in caves and adaptation to subterranean life. We focus on seven north temperate regions of at least 2000 km2, utilizing more than 4300 records of obligate cave-dwelling terrestrial invertebrates. In North America, highest diversity was found in northeast Alabama while in Europe highest diversity was found in Ariege, France, and in southeast Slovenia. Based on these regions as well as more qualitative data from 16 other regions, we hypothesize that a ridge (ca 42°–46° in Europe and 34° in North America) of high biodiversity occurs in temperate areas of high productivity and cave density. This may reflect a strong dependence of cave communities on long term surface productivity (as reflected in actual evapotranspiration), because the subterranean fauna relies almost entirely on resources produced outside caves. This dependence may explain the unique biodiversity pattern of terrestrial cave invertebrates.

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The copepod crustacean fauna collected from subterranean habitats, including caves, wells, and the hyporheos of streams in and near the Interior Low Plateaus of the United States is dominated by Cyclopoida, with 39 species, followed by Harpacticoida with 9, and Calanoida with 2. Nearly all of the harpacticoid and calanoid species are widespread, primarily surface-dwelling generalists. Fourteen of the cyclopoids, members of the genera Diacyclops, Itocyclops, Megacyclops, and Rheocyclops, are apparently obligate stygobionts or hyporheic. Several of the species that are more strongly modified for subterranean existence occur only in the more southern, unglaciated areas. Our sampling data support the hypothesis that the more specialized, groundwater-interstitial species have been unable to disperse into previously glaciated regions; whereas some, less-specialized species may have invaded groundwaters from surface habitats as the glaciers receded.

Nine species of asellid isopods are reported from groundwater habitats in Maryland. Three of these species are habitually found in springs: Lirceus brachyurus, Caecidotea kenki, and C. alleghenyensis, n. sp. The latter, described herein, is a member of the hobbsi group known only from the Allegheny Mountains in Garrett Co. Six species are obligate inhabitants of subterranean waters and are found primarily in Appalachian caves, although some have broad ranges that span noncavernous areas. The obligate subterranean species are Caecidotea pricei, C. franzi, C. holsingeri, C. mausi, C. vandeli and C. nordeni.

Six new species of the milliped genus Pseudotremia are described and illustrated from caves of the Cumberland Plateau in east-central Tennessee (USA): Pseudotremia barri, P. garlandae, P. hollidayi , P. manni , P. roebuckorum , and P. wallaceae . The degree of troglomorphism in these species varies, leaving their ecological status as troglobites versus troglophiles uncertain. New records of P .acheron Shear and P. minos Shear are given, and the probable extinction of the Nickajack Cave population of P. eburnea Loomis is noted. Many species in Pseudotremia remain undescribed, making discussion of the zoogeography or evolution of the group inconclusive until the genus is better known.