Phylum Platyhelminthes

Order Tricladida (flatworms)

While several flatworms are represented in Arkansas caves, only a single species, Dendrocoelopsis americana, could be considered a troglobite. Many populations of D. americana are eyed, but an eyeless population was reported from a well in Texas (Kawakatsu and Mitchell 1984). Cave flatworms are not well represented in Arkansas, but may reflect minimal collecting effort rather than lack of species (Slay et al. 2006).

Cave flatworm - Dendrocoelopsis americana

Phylum Mollusca

Class Gastropoda (snails)

No terrestrial snails are troglobites in Arkansas. Several species such as Inflectarius inflectus and Patera perigrapta are common at cave entrances, and accumulations of empty shells are observed short distances inside caves. Many terrestrial snail shells are probably washed inside caves from the forest floor. Although several aquatic troglobitic snails (Hydrobiidae) occur in Missouri (Elliott 2007), Arkansas has only one. Amnicola cora is known from a single cave in Independence County (Hubricht 1979).

Phylum Arthropoda

Class Crustacea

Subclass Podocopa (ostracods)

One or more undescribed, troglobitic ostracods were collected from cave crayfish Cambarus aculabrum and C. zophonastes, respectively. Hobbs and Bedinger (1964) reported an Uncinocythere from C. zophonastes, accorded it specific rank, but a species description was not completed. Recently, commensal ostracods were collected from C. aculabrum, but remain unidentified.

Subclass Malacostraca

Order Amphipoda (amphipods)

Six described species of troglobitic amphipods can be found in Arkansas caves. Allocrangonyx hubrichti is known from a single well in White County (Robison and Holsinger 2000). In Missouri, this species is more common than previously thought (Sarver and Lister 2004), and it is expected to be found in additional groundwater habitats in Arkansas. Three species of Stygobromus are known, several which are relatively common (Graening et al. 2005). An additional Stygobromus is undescribed. Two Bactrurus are known with B. speleopolis being one of the largest cave amphipods in North America (Holsinger et al. 2006).

*Cave amphipod - Allocrangonyx hubrichti

Order Isopoda (isopods)

Troglobitic aquatic isopods are fairly common in Arkansas caves. Quite often asellid isopods of the genus Caecidotea are observed in spring resurgences and groundwater seeps in addition to cave streams. Eight troglobitic Caecidotea are known (Graening et al. in press). Several species, such as C. macropropoda, C. simulator, C. steevesi, and C. stiladactyla are predominant in western Arkansas caves, while species, such as C. dimorpha and C. salemensis are found in eastern Arkansas caves. Other species, such as C. ancyla and C. antricola are known from caves across northern Arkansas. Terrestrial isopods are also common, but most are exotic surface species such as Armadillidium vulgare and Haplothalmus danicus. A native surface species sometimes observed is Ligidium elrodii (Graening et al. in press). Two genera of troglobitic terrestrial isopods occur in Arkansas caves. An undescribed Miktoniscus is known from 2 caves, and recently, an undetermined Brackenridgia was collected from several caves and abandoned zinc mines.

Order Decapoda (crayfish)

Three crayfish are troglobites in Arkansas. Cambarus aculabrum is known from four caves in northwest Arkansas, and observed individuals are exceedingly rare (Graening et al. 2006). At two sites, single individuals were flushed into accessible habitats during intense rain events. Another rare cave crayfish is C. zophonastes documented from two Stone County caves (Graening et al. 2006). The third cave crayfish, C. setosus, has an interesting distribution in Arkansas. The species is well documented from multiple sites in southwestern Missouri, and the populations of C. setosus found in northwest Arkansas easily expand the known distribution. However, a morphologically similar but disjunct population is known from a single cave in Independence County (Graening et al. 2006). The location of this outlier population is difficult to explain and represents a range extension of approximately 250 km southeast from the distribution center in Missouri. Several additional populations of cave crayfish occur in Arkansas, but remain unidentified.

*Benton cave crayfish - Cambarus aculabrum

*Bristly cave crayfish - Cambarus setosus

*Delaware County cave crayfish - Cambarus subterraneus

Class Arachnida

Order Araneae (spiders)

Only a few troglobitic spiders are reported from Arkansas, and all three species occur in the family Linyphiidae. Two species are known from single sites, while the third is more widespread. Phanetta subterranea is known from a single cave in Stone County (Youngsteadt and Youngsteadt 1978), and Bathyphantes weyeri is known from a single cave in Washington County (Ivie 1969). More common is Porrhoma cavernicola known from caves in six counties across Arkansas (McDaniel et al. 1979, Peck and Peck 1982, Graening and Slay unpublished data).

Fishing spider - Dolomedes sp.

Cave orb weaver - Meta ovalis

Order Pseudoscorpionida (psuedoscorpions)

Three troglobitic pseudoscorpions in two families are known from Arkansas caves. Two single site endemics are known from the family Chthoniidae. Apochthonius diabolus was described from a single male collected in 1958 from Devils Den Cave, Washington County, by Muchmore (1967). Interestingly, revisits to this site failed to note the presence of this species until recently (Slay and Taylor unpublished data). The second chthoniid Apochthonius titanicus was described from several specimens collected near the base of “The Titans” in Blanchard Springs Caverns, Stone County (Muchmore 1976). Specimens of potentially new troglobitic Apochthonius have been collected from caves in several Arkansas counties but remain undetermined. The third troglobite is fairly widespread. Hesperochernes occidentalis (Chernitidae) is known from caves in 10 counties across Arkansas (W. Muchmore personal communication).

*Cave pseudoscorpion - Hesperochernes occidentalis

Order Opiliones (harvestman)

Quite often, members of the common daddy-long-legs genus Leiobunum (Sclerosomatidae) are observed in entrances of Arkansas caves, and the smaller, gray-colored, troglophile Sabacon cavicolens (Sabaconidae) is also easily found. A single family, Phalangodidae, has produced troglobites in Arkansas caves. An eyeless species Crosbyella distincta is known from a single cave in Boone County, while an eyed species C. roeweri is known from a single cave in Benton County (Goodnight and Goodnight 1942). Adults of these harvestmen are small and orange-colored, while juveniles are nearly white.

*Cave harvestman - Crosbyella distincta

Sabaconid harvestman - Sabacon cavicolens

Class Diplopoda (millipeds)

Troglobitic millipeds are represented by species in several families. Recently, Shear (2003) erected the genus Causeyella (Trichopetalidae) based on Scoterpes dendropous and described two additional species, C. youngsteadtorum and C. causeyae. The first species, C. dendropus, is known from Missouri and Arkansas caves, while the latter two troglobites are known only from Arkansas. Another troglobite known from Missouri and Arkansas represents the family Tingupidae. Much more common in Missouri than Arkansas, Tingupa pallida, is known from a cave in Randolph County and a cave in Sharp County (Shear 1981). Finally, a troglobitic Chaetapsis (Macrosternodesmidae) is known from a cave in Independence County and awaits description (Lewis 2002).

Class Insecta

Order Collembola (springtails)

In Arkansas caves, seven troglobitic springtails are known. A recent addition to the troglobitic springtail fauna is Typhlogastrura fousheensis, described from Foushee Cave by Christiansen and Wang (2006). The other troglobites are: Arrhopalites clarus, Pseudosinella dubia, P. georgia, P. testa, Tomocerus missus, and Sinella barri. Several troglobitic springtails, 2 Arrhopalites and 1 Pseudosinella, await description. Arrhopalites clarus is the only common species and occurs in caves across Arkansas (Christiansen unpublished data, Zeppelini et al. unpublished data). Troglophilic springtails are easily seen, and Tomocerus flavescens is often observed in the entrances and twilight zones of caves.

Arrhopalitid springtail - Arrhopalites sp.

*Cave springtail - Psuedosinella dubia

Onychiurid springtail - Onychiuridae

Order Diplura (diplurans)

Two families of diplurans contain troglobites in Arkansas caves. The family Campodeidae has two long, bristly, antennae-like tails, and members of this family can be very common in specific caves. In Arkansas, two undescribed troglobitic species of Litocampa are reported (Ferguson unpublished data). Interestingly, the ranges of these two species overlap, and they may both occur in the same cave. The family Japygidae has forceps or pincher-like tails, but in contrast, the family is uncommon in Arkansas caves. Specimens have been collected from several caves in Newton and Marion County and may represent several new species (M. Meugge personal communication).

*Cave dipluran - Litocampa sp.

Order Thysanura (silverfish)

An undescribed species of troglobitic Nicoletiidae is known from several caves in Benton and Newton County and from a few neighboring caves in Oklahoma. The discovery of this species represents the first record for the family in Arkansas. The species appears to be very rare, and collection of individuals has been random. Multiple revisits to known caves have failed to observe additional specimens.

*Cave thysanuran - Nicoletiidae

Order Coleoptera (beetles)

While two troglobitic beetles are known from Missouri caves (Barr and Krekeler 1967), none are reported in Arkansas. A rare carabid Rhadine ozarkensis is known from a single cave in Washington County (Sanderson and Miller 1941), but unlike many members of this genus, this species is eyed and appears to be a troglophile (Barr 1974). Other troglophilic beetles in the families Carabidae, Leiodidae, and Staphylinidae are very common and easily observed in caves across Arkansas.

Order Diptera (flies)

Flies are probably the most common invertebrate group in Arkansas caves, and the highest abundance come from the families Mycetophilidae, Phoridae, and Sphaeroceridae. Most of these species are considered troglophiles, but one sphaerocerid Spelobia tenebrarum is a troglobite. Abundances of S. tenebrarum can be quite high, and the species occurs in caves across the state.

Moth Fly - Psychodidae

Mosquito - Culicidae

Heleomyzid fly - Heleomyzidae

Webworm (larvae) - Macrocera nobilis

Webworm (adult) - Macrocera nobilis

Phylum Chordata

Class Actinopterygii

Order Perciformes (cavefish)

There are two named and one undescribed cavefish in Arkansas, and all 3 are in the family Amblyopsidae. The Ozark cavefish (Amblyopsis rosae) is listed as threatened by the U.S. Fish and Wildlife Service, and the species occurs in less than 10 sites in Arkansas. The number of observed fish at these sites is never more than 2-3 individuals, expect at two caves: Logan Cave and Cave Springs Cave. Cave Springs Cave has the largest observable population where 120-150 fish are consistently seen. The second cavefish Typhlichthys subterraneus is reported from two eastern Arkansas sites, a cave in Fulton County and a well in Randolph County (Woods and Inger 1957, Paige et al. 1981). Recently, a third cavefish was collected from several sites in Stone County and is undergoing taxonomic study.

*Ozark cavefish - Amblyopsis rosae

*Undescribed cavefish - Typhlichthys n. sp.

Class Amphibia

Order Urodela (salamanders)

Arkansas has one troglobitic salamander Eurycea spelaea or grotto salamander. The grotto salamander was formerly called Typhlotriton spelaeus, but recent genetic study has shown that the species should be placed in the genus Eurycea (Bonett and Chippindale 2004). Grotto salamanders have interesting life histories; the juvenile stage is aquatic, pigmented, eyed, and can sometimes be found outside of caves in spring runs. When juveniles transform to adults, they lose pigment and functional eyes, are terrestrial, and live deep in caves. The species can be found in caves across Arkansas.

*Grotto salamander - Eurycea spelaea

Cave salamander - Eurycea lucifuga

Dark-sided salamander - Eurycea longicauda melanoplura

Ozark Zig-zag salamander - Plethodon dorsalis angusticlavius

Slimy salamander - Plethodon albagula