> Habitat & Distribution

Fontigens orolibas inhabits springs and cave streams from the Potomac River basin of southern Pennsylvania southwest to the Clinch and Holston Rivers of southwestern Virginia and east Tennessee, including parts of the New and Roanoke River basins (Hershler et al. 1990, Gladstone et al 2021).  Populations are especially common in springs and wet seeps at the crest of the Blue Ridge along the Skyline Drive in Shenandoah National Park (Hubricht 1957).  We also have scattered records further south in the Roanoke, New and upper Tennessee drainages.  

A broad-brush review of the zoogeography of North American cavesnails has been offered by Hershler & Holsinger (1990), and a more detailed review for the genus Fontigens by Gladstone and colleagues (2021).

The animals themselves are very pale and seem to shun the light, being found underneath stones and leaves very near their springhead.  Population densities become rapidly attenuated downstream, as though dependent on constant temperature or some other unique aspect of the spring environment.  FWGNA incidence rank I-4.

> Ecology & Life History

The cryptic habit of F. orolibas seems to suggest a diet that does not ordinarily include algae, but rather very fine organic matter or bacteria, and possibly a subterranean lifestyle. The springs at the crest of the Blue Ridge inhabited by Fontigens orolibas are quite soft, but elsewhere the species seems to inhabit harder waters.

We are not aware of any good study on the life history of Fontigens orolibas, but populations typically seem to maintain high densities year round, as though reproduction might be continuous.  Weck (2022) reported approximately one year to maturity (3 mm) in laboratory populations of the cave-dwelling Fontigens antroecetes, constant low levels of reproduction (25 - 80 eggs/pair/yr), and a lengthy hatch time of 70 - 80 days.

> Taxonomy & Systematics

The multivariate study of Gladstone et al. (2021) confirmed that the shell morphology of Fontigens orolibas is distinct from most of the other recognized species studied, although not from F. tartarea or F. turritella, more common in West Virginia.  Gladstone and colleagues also published a nice photomontage of F. orolibas, both of the shell and the living animal.

Hershler and colleagues (1990) nominated Fontigens orolibas as the type of an "orolibas group" (which included F. tartarea) characterized by a tripartite penis with a tubular distal lobe and a bulbous proximal lobe.  Hershler distinguished this four-species group from the three-species group of Fontigens nickliniana, bearing a tripartite penis with a pair of tubular lobes.  The mtDNA sequence study of Liu and colleagues (2021), across 13 populations of 9 Fontigens species, confirmed a genetic distinction between the two Hershler groups.   For a review of that paper, see my blog post of 9Aug22 from the link below.

The 13 populations of Liu and colleagues included samples of F. orolibas from Page, Augusta, and Tazewell Counties of Virginia.  Gladstone et al. (2021) contributed mtDNA data from a fourth population in Knox County, TN, to which Dillon and colleagues (in prep) added a fifth data set from Giles County, VA.

Taylor (1966) suggested that Fontigens comprises a distinct hydrobiid subfamily, the Fontigentinae, which Hershler et al. (1990) synonymized under the Emmericiinae of Brusina (1870).  Wilke et al. (2013) did not confirm a close association between Fontigens (represented by a single sample) and the European genus Emmericia, however, tentatively returning the Fontigentinae to subfamilial status.  Despite this evidence, self-appointed experts insisted on placing Fontigens in the Emmericiidae for several years (Bouchet et al. 2017), until Gladstone & Whelan (2022) split the genus to its own separate family, the Fontigentidae.

> Maps and Supplementary Resources

• Fontigens and Holsingeria in Atlantic drainages (2023)
• Fontigens in drainages of The Ohio (2019)
• Fontigens in drainages of the Tennessee/Cumberland (2022)
• Virginia species account with county distribution (2011)

> Essays

• I wrote a blog post inspired by a day of hunting for Fontigens orolibas on 26July06 entitled "Springsnails of the Blue Ridge."  Several photos are included with that essay, including one of a living F. orolibas compared to F. nickliniana.
• Earlier versions of this website, online until August of 2016, adopted the large, broadly-inclusive concept of the Hydrobiidae (sl) following Kabat & Hershler (1993).  More recently the FWGNA project has shifted to the Wilke et al. (2013) classification system, distinguishing a much smaller Hydrobiidae (ss) and elevating many hydrobioid taxa previously ranked as subfamilies to the full family level.  For more details, see The Classification of the Hydrobioids.
• See my essay of 9Aug22, Startled by Fontigens, sort-of, I suppose for a review of the paper by Liu et al. (2021) documenting unusually high levels of intraspecific mtDNA sequence divergence in F. orolibas.

> References

Bouchet, P., J. Rocroi, B. Hausdorf, A. Kaim, Y. Kano, A. Nutzel, P. Parkhaev, M. Schrodl, and E. Strong (2017) Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia, 61: 1–526.
Gladstone, N.S., E. Pieper, S. Keenan, A. Paterson, M. Slay, K. Dooley, A. Engel, and M. Niemiller (2021)  Discovery of the Blue Ridge springsnail, Fontigens orolibas Hubricht 1957 (Gastropoda: Emmericiidae) in East Tennessee and its conservation implications.  Freshwater Mollusk Biology and Conservation 24: 34 - 42.
Gladstone, N. S. and N. Whelan (2022) Pushing barcodes to their limits: phylogenetic placeament of Fontigens Pilsbry, 1933 (Caenogasatropoda: Littorinimorpha: Truncatelloidea) and elevation of Fontigentidae Taylor, 1966.  Journal of Molluscan Studies 88: eyab038.
Hershler, R. H. & J. R. Holsinger (1990)  Zoogeography of North American hydrobiid cavesnails.  Stygologia 5: 5-16.
Hershler, R., J.R. Holsinger & L. Hubricht (1990) A revision of the North American freshwater snail genus Fontigens (Prosobranchia: Hydrobiidae). Smithsonian Contributions to Zoology 509:1-49.
Hubricht, L. (1957) New species of Fontigens from Shenandoah National Park.  Nautilus 71: 9 - 10.
Hubricht, L. (1976)  The genus Fontigens from Appalachian caves (Hydrobiidae: Mesogastropoda).  Nautilus 90:86 - 88.
Kabat, A.R., and R. Hershler (1993) The prosobranch snail family Hydrobiidae (Gastropoda: Rissooidea): review of classification and supraspecific taxa. Smithsonian Contributions to Zoology 547:1-94. 
Liu, H-P., L. Schroeder, A. Berry, and R. T. Dillon, Jr. (2021)  High levels of mitochondrial DNA sequence divergence among isolated populations of Fontigens (Truncatelloidea: Emmericiidae) in eastern USA.  Journal of Molluscan Studies 87:  eyab026. [pdf]
Stewart, T. W., & R. T. Dillon, Jr.  (2004)  Species composition and geographic distribution of Virginia's freshwater gastropod fauna: A review using historical records.  Am. Malac. Bull. 19: 79-91.
Taylor, D.W. (1966) Summary of North American Blancan nonmarine molluscs.   Malacologia  4: 1 - 172.
Weck, R.G. (2022)  Life history observations of the Illinois state endangered Enigmatic Cavesnail, Fontigens antroecetes (Hubricht, 1940) made under simulated cave conditions.  Subterranean Biology 43: 185 - 198. 
Wilke T., Haase M., Hershler R., Liu H-P., Misof B., Ponder W. (2013)  Pushing short DNA fragments to the limit: Phylogenetic relationships of “hydrobioid” gastropods (Caenogastropoda: Rissooidea).  Molecular Phylogenetics and Evolution 66: 715 – 736715 – 736.