Corresponding author: Matthew L. Niemiller ( email@example.com )
Academic editor: Oana Moldovan
© 2016 Matthew L. Niemiller, Kirk S. Zigler, Pamela B. Hart, Bernard R. Kuhajda, Jonathan W. Armbruster, Breanne N. Ayala, Annette S. Engel.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Niemiller ML, Zigler KS, Hart PB, Kuhajda BR, Armbruster JW, Ayala BN, Engel AS (2016) First definitive record of a stygobiotic fish (Percopsiformes, Amblyopsidae, Typhlichthys) from the Appalachians karst region in the eastern United States. Subterranean Biology 20: 39-50. https://doi.org/10.3897/subtbiol.20.9693
In the central and eastern United States, cavefishes have been known historically only from the Interior Low Plateau and Ozarks karst regions. Previously, cavefishes were unknown from the Appalachians karst region, which extends from southeastern New York southwestward into eastern Tennessee, northwestern Georgia, and northeastern Alabama. Here we report the discovery of a new population of the amblyopsid cavefish Typhlichthys subterraneus Girard, 1859 from a cave in Catoosa County, Georgia, that significantly extends the known distribution of the species. The cave is located in the Appalachian Valley and Ridge physiographic province and Appalachians karst region, and represents the first definitive report of a stygobiotic fish from the Appalachians karst region. Genetic analyses of one mitochondrial and one nuclear locus from the cavefish indicate this population is closely allied with populations that occur along the western margins of Lookout and Fox mountains in Dade County, Georgia, and populations to the northwest in southern Marion County, Tennessee. It is likely that these populations are also related to those from Wills Valley, DeKalb County, Alabama. The distribution of this new population of T. subterraneus and its close allies pre-dates the emergence of a Tennessee-Coosa River drainage divide in the Pliocene. The potential exists to discover additional populations in caves within the Appalachians karst region in Catoosa County and northward into Hamilton County, Tennessee.
Appalachian Valley and Ridge, Catoosa County, cavefish, Cumberland Plateau, Georgia, range extension
Of the more than 50,000 caves reported in the United States, about 30% occur in the states of Tennessee, Alabama, and Georgia (TAG). The two most biodiverse karst regions in the United States – the Interior Low Plateau (ILP) and Appalachians – occur in this region (
The ILP and Appalachian karst regions contain the most caves and have the greatest richness of troglobiotic taxa in the United States (
Several factors may explain differences in species richness between these the ILP and Appalachians karst regions, such as differences in habitat availability, habitat connectivity, historical factors, and surface productivity (
Typhlichthys subterraneus s.l. Girard, 1859 is one of the most wide-ranging cavefishes in the world (
Crane Cave (Georgia Speleological Survey cave no. GCZ80) is located ca. 7 km SSE of Fort Oglethorpe, Georgia, in the South Chickamauga Creek watershed. Crane Cave formed in the Ordovician Newala Limestone, and has 292 m of mapped length with 11 m of vertical extent and three entrances. A small stream runs through the cave and emerges at the spring entrance. The stream begins in a large pool at the back of the cave called “The Found Sea.” The pool is ca.10 m in length and ca. 6 m in width, and has a mud/silt substrate bottom. The full extent of the pool is unknown, as it extends underneath a ledge at the back of the cave. At base level, water depth is ca. 2 m deep in the deepest portion of the pool.
Crane Cave was visited on four occasions: 10 August 2015, 18 August 2015, 29 October 2015, and 25 November 2015. The Found Sea and other aquatic habitats were sampled using time-constrained visual surveys with headlamps and handheld dive lights. Richness and abundance data for aquatic fauna were recorded, and a concerted effort was made to capture fish with handheld dipnets. A voucher specimen and tissue sample (fin clip) was obtained for morphological and genetic analyses.
Genomic DNA was extracted from fin clips using the EZNA DNA Extraction Kit (Omega Biotek). Two gene loci were chosen from six previously used by
Forward and reverse sequences were aligned into contigs and edited with manual verification using Geneious v. 6.0.6 (Biomatters Ltd.). Maximum likelihood gene trees were generated for both ND2 and S7 loci with raxmlGUI v.1.31 (
A single cavefish was observed in The Found Sea of Crane Cave but evaded capture during an initial bioinventory on 10 August 2015. No cavefish were observed during two subsequent trips on 18 August 2015 and 29 October 2015. Two cavefishes were observed on 25 November 2015. One specimen was collected and retained as a voucher specimen (Fig.
Other notable fauna observed during the four biological surveys at Crane Cave included aquatic species Crangonyx antennatus Cope & Packard, 1881 (Amphipoda: Crangonyctidae), Caecidotea richardsonae Hay, 1901 (Isopoda: Asellidae), and Cottus sp. (Scorpaeniformes: Cottidae), and terrestrial species Hesperochernes mirabilis (Banks, 1895) (Pseudoscorpiones: Chernetidae), Bishopella sp. (Opiliones: Phalangodidae), Amoebaleria sp. (Diptera: Heleomyzidae), and Eidmanella pallida (Emerton, 1875) (Araneae: Nesticidae).
Molecular results indicated that the Crane Cave specimen was most closely related to the T. subterraneus populations designated lineage A in both the ND2 and S7 phylogenies (
Maximum likelihood gene trees for mitochondrial ND2 (left) and nuclear S7 (right) loci. Colors correspond to genetic lineages for Typhlichthys subterraneus designated in
Distribution of Typhlichthys subterraneus (solid circles) in southeastern Tennessee, northeastern Alabama, and northwestern Georgia. The new record at Crane Cave is denoted with a red triangle and lineage A localities are highlighted in peach. Lineage A populations that have been genetically examined are marked with an asterisk and labeled as follows: LMC – Limestone Caverns, LPC – Lost Pig Cave, LRW – Long’s Rock Wall, and PCS – Pryor Cave Spring. Counties with Typhlichthys records are labeled. Karst and cave-bearing strata are shaded gray based on the U.S. karst map (
The range of Typhlichthys subterraneus s.l. extends throughout the ILP of Kentucky, Tennessee, Alabama, and Georgia, which makes it one of the largest distributions of any cavefish in the world (
Analyses of the mitochondrial ND2 and the nuclear S7 loci from Crane Cave T. subterraneus strongly support affinity to lineage A (as defined by
There is the issue of whether the other T. subterraneus populations in lineage A, specifically those in Wills Valley formed in Cambrian-Ordovician Knox group dolomites in AVR-style structural valleys, are also considered AVR distributions or ILP distributions. The physiographic distinction of Wills Valley has been a matter of debate in the literature. Wills Valley is an anticlinal valley flanked by Sand Mountain to the west and Lookout Mountain to the east. Both ridges are considered parts of the Cumberland Plateau (
Another important aspect of T. subterraneus in Wills Valley is that these populations are in the Coosa River watershed, which flows into the Alabama River and then Mobile Bay. Crane Cave occurs in the South Chickamauga Creek watershed, which flows into the Tennessee River. Moreover, all four documented populations in Dade County, Georgia, occur in the Lookout Creek watershed, and the caves in Marion County, Tennessee, are part of the Sequatchie River watershed. Both Lookout Creek and the Sequatchie River empty into the Tennessee River, which eventually flows into the Ohio River and then the Mississippi River. River drainages in the southern region of North America and the Appalachian Mountains became established at least by the Eocene, 55 Mya (
Today, the Tennessee and Coosa rivers are separated by a divide, whereby the southern part of Wills Valley flows to the Coosa River and the northern section flows to the Tennessee River. The genetic affiliation of the Crane Cave T. subterraneus population to lineage A (
In conclusion, although no additional cavefish populations have been discovered in the past several years (
We particularly thank Mary and Ron Ziegler for allowing us to visit Crane Cave and for welcoming us on several return trips. Funding and support for this project was provided by the Cave Conservancy Foundation and the University of the South. We thank the Georgia Speleological Survey for providing data and a map of Crane Cave. This work was permitted by the Georgia Department of Natural Resources under scientific collection permit no. 8934 and approval by the University of the South IACUC committee (KSZ).