DESCRIPTION OF LIRCEUS FOUSHEENSIS, N. SP., THE FIRSTTROGLOMORPHIC ISOPOD OF THE GENUS LIRCEUS (HOPPINELLUS) FROMTHE OZARKS (CRUSTACEA: ISOPODA: ASELLIDAE)
Publication Date: 2026/06/01
Publication Volume: Journal of Cave and Karst Science 88 #1
DOI Link: https://dx.doi.org/10.4311/2025LSC0102
ABSTRACT:
Troglomorphic, stygobiontic asellid isopods of the genera Caecidotea and Conasellus are widespread in the Ozark physiographic province of the central United States. In contrast, numerous species of Lirceus are common in springs and seeps where groundwaters emerge, but none are particularly morphologically adapted to caves. Herein, we describe and figure Lirceus fousheensis, the first troglomorphic (and presumably stygobiontic) species of the genus in the Ozarks, from Foushee Cave, Independence County, Arkansas. It is a species of the Lirceus bicuspidatus clade and is viewed as an isolated cave invasion arising by an adaptive shift from a common spring-dwelling species. Compared with seven cavernicolous species of Lirceus from southwestern Virginia caves, Lirceus fousheensis is intermediate in the degree of troglomorphism.
SIMPLE LANGUAGE SUMMARY:
Isopods are small crustaceans related to pill bugs, and some kinds live in freshwater streams, springs and caves. In the Ozark region of the central United States, cave-adapted isopods from two genera, Caecidotea and Conasellus, are common. Members of a third genus, Lirceus, are also common in the region, but they live in springs and seeps at the surface and none had ever been found that showed real adaptations to cave life. In this paper the authors describe a new species, Lirceus fousheensis, from Foushee Cave in Independence County, Arkansas. It is the first Lirceus in the Ozarks that is troglomorphic, meaning it shows the classic cave-adapted traits of reduced eyes and a loss of body pigment. It also has simpler versions of some of the structures males use in reproduction, which is another pattern seen in cave-dwelling relatives. The species is a close relative of Lirceus bicuspidatus, a common spring-dwelling isopod, and the authors think it arose when a population of that ancestor moved into the cave and adapted to life in permanent darkness. DNA evidence supports this: the pale cave isopods form a separate genetic group from the fully pigmented isopods living in the spring stream just outside the cave entrance. The new species is known only from Foushee Cave, which is also the only known home of a cave snail called Amnicola cora. When compared with seven cave-dwelling Lirceus species from caves in southwestern Virginia, Lirceus fousheensis falls about in the middle in terms of how strongly cave-adapted it is. The suggested common name is the Foushee cave isopod.
REFERENCES:
Graening, G.O., 2003, Subterranean biodiversity of Arkansas, Part 2: Status update of the Foushee cavesnail, Amnicola cora Hubricht, 1979 (Mollusca: Gastropoda: Hydrobiidae): Journal of the Arkansas Academy of Science, v. 57, p. 195–196.
Graening, G.O., Fenolio, D.B., and Slay, M.E., 2011, Cave life of Oklahoma and Arkansas: Norman, University of Oklahoma Press, 226 p.
Hubricht, L., and Mackin, J.G., 1949, The freshwater isopods of the genus Lirceus (Asellota: Asellidae): American Midland Naturalist, v. 42, no. 2, p. 334−349, https://doi.org/10.2307/2422012.
Lewis, J.J., and Lewis, S.L., 2023, Freshwater isopods of the genus Lirceus from caves and springs of the Interior Highlands, USA, with descriptions of three new species (Isopoda: Asellidae): Journal of Cave and Karst Studies, v. 85, no. 3/4, p. 86–101, https://doi.org/10.4311/2022LSC0113.
Lewis, J.J., Lewis, S.L., Orndorff, W., Orndorff, Z., Malard, F., Konecny-Dupré, L., Saclier, N., and Douady, C., 2023, The groundwater isopods of Virginia (Isopoda: Asellidae and Cirolanidae), Virginia Museum of Natural History: Special Publication 19, 214 p.
McDaniel, V.R., and Smith, K.L., 1976, Cave fauna of Arkansas: Selected invertebrate taxa: Arkansas Academy of Science Proceedings, v. 30, p. 57–60.
Saclier, N., Duchemin, L., Konecny-Dupré, L., Grison, P., Eme, D., Martin, C., Callou, C., Lefébure, T., François, C., Issartel, C., Lewis, J.J., Stoch, F., Sket, B., Gottstein, S., Delić, T., Zagmajster, M., Grabowski, M., Weber, D., Reboleira, A.S.P.S., Palatov, D., Paragamian, K., Knight, L.R.F.D., Michel, G., Lefebvre, F., Hosseini, M.-J.M., Camacho, A.I., De Bikuña, B.G., Taleb, A., Belaidi, N., Tuekam Kayo, R.P., Galassi, D.M.P., Moldovan, O.T., Douady, C.J., and Malard, F., 2024, A collaborative backbone resource for comparative studies of subterranean evolution: The World Asellidae database: Molecular Ecology Resources, v. 24, no. 1, p. e13882, https://doi.org/10.1111/1755-0998.13882.
