FWGNA > Species Accounts > Hydrobiidae > Fontigens sp. 2
Fontigens species 2 (undescribed)

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> Habitat & Distribution

Populations of Fontigens species 2 inhabit streams draining caves of the Wabash Spring Basin, a tributary of the New River in Giles County, VA.  Two populations have been documented: one in the main stream of the Sugar Run Cave System and a second in the main stream of Dulaney's Cave.  The snails are found grazing on and under rocks and cobbles.  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 species 2 is apparently stygobiontic, entirely unpigmented and blind, known only from caves.  

We are not aware of any good study on the life history of any population in the genus Fontigens, 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 species 2, 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 will be among three newly described by Dillon and colleagues in an appendix to the forthcoming Volume V of the FWGNA series.  It is a member of the "orolibas group" of Hershler et al. (1990), bearing a tripartite penis with a tubular distal lobe and a bulbous proximal lobe.  It may be distinguished from all other species of Fontigens by its unique ovoid or fusoid shell and a minimum CO1 sequence divergence of 9.2% from all previously -sequenced species and 9.1% from Fontigens species 3, with which it co-occurs, from which it appears to be reproductively isolated.

A survey of CO1 sequence diversity across 13 populations of 9 Fontigens species was offered by Liu and colleagues (2021).

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. 

> Supplementary Resources

  • Montage of Fontigens sp 2 shells, from unpublished description.Pretty photo

> 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.

> 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. (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.
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.