> Habitat & Distribution

Populations of Fontigens hershleri inhabit the main stream draining Lane Cave, a tributary of Copper Creek in the Clinch River subbasin of Scott County, VA.  The snails are found grazing on and under stones.  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).  FWGNA incidence unranked.

> Ecology & Life History

Fontigens hershleri is stygophilic, possibly stygobiontic.  The single known population is associated with juveniles of the above-ground-dwelling Pleurocera simplex, suggesting that the Lane Cave stream in which they were discovered communicates with the outside.  Their pigmented bodies suggest that they might inhabit above-ground waters as well.

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.

We are not aware of any good study on the life history of any population in the genus Fontigens in the field, stygobiontic or otherwise.  But populations (of all species) typically seem to maintain constant densities year round, as though reproduction might be continuous.  This would certainly seem a reasonable assumption for Fontigens hershleri, living nearly divorced from seasonal cues.  The waters of limestone caves are (of course) rich in minerals, but poor in organics.  Presumably the entire ecosystem is based on fine organic matter raining down from the lighted world above.

> Taxonomy & Systematics

This species was among three newly described by Dillon and colleagues in an appendix to Volume 5 of the FWGNA series (Dillon et al. 2023).  It is a member of the "nickliniana group" of Hershler et al. (1990), bearing a tripartite penis with two tubular lobes.  It may be distinguished from all other species of Fontigens by its unique ovate-conic shell morphology and a minimum CO1 sequence divergence of 13.1% from all previously-sequenced species.

A survey of CO1 sequence diversity across 13 populations of 9 Fontigens species was offered by Liu and colleagues (2021).  See my essay of 9Aug22 from the link below for a review.

Taylor (1966) suggested that Fontigens comprised 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. 

> Supplementary Resources

• Fontigens distribution in the Tennessee/Cumberland drainage (2022)
• Montage of Fontigens hershleri shells, from Dillon et al. (2023).
  

> Essays

• 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.
• I shared the backstory behind the discovery and description of Fontigens hershleri, F. benfieldi, and F. davisi in my essay of 9Jan24, Three New Fontigens From Virginia. Additional photos showing shell variation are also available.

> 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.
Dillon, R.T., Jr., T.E. Malabad, W.D. Orndorff & H-P. Liu (2023) Three new Fontigens (Caenogastropoda: Fontigentidae) from caves in the Appalachian Ridge and Valley Province, Virginia. Pp. 283 - 306 in Dillon, R.T., Jr. et al. The Freshwater Gastropods of North America Volume V: Ohio, Cumberland, and Tennessee River Systems. FWGNA Press, Charleston. [pdf]
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. (1963)  New species of Hydrobiidae.  Nautilus 76: 138 - 140.
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. 
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 – 736.