FWGNA > Species Accounts > Lithoglyphidae > Clappia umbilicata
Clappia umbilicata (Walker 1904)

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> Habitat & Distribution

The hydrobiid genus Clappia was for many years believed endemic to the Mobile Basin of Alabama, where populations are quite rare, and have been feared extinct.  We first discovered small populations of C. umbilicata in the upper Powell and Sequatchie Rivers of Tennessee in 2008-10, but our samples remained unidentified until late 2012.  In both rivers, the preferred habitat seems to be calmer backwaters and marginal pools, where individual snails are most commonly observed on sticks and other organic debris.  FWGNA Incidence rank I-2, rare.

> Ecology & Life History

Hydrobioids seem to be rather nonspecific grazers of small particles (Dillon 2000: 94-97).  They are typically dioecious, the males being characterized by a penis that arises from the neck.  Eggs are generally laid singly, attached in a spare capsule to a solid substrate.  I am unaware of any good study on any aspect the biology of Clappia.

> Taxonomy & Systematics

The hydrobioids are the most diverse and taxonomically difficult group of freshwater gastropods - snails of great anatomical variety packaged in dauntingly nondescript little containers.   Penial morphology in the family Lithoglyphidae is simple and unlobed, with just the single duct.  Of the three lithoglyphid genera inhabiting surface waters of the American southeast, Gillia is distinguished by its relatively large size (adults 6-8 mm) and Somatogyrus by its relatively robust shell.  Clappia is neither large nor heavily-shelled, the most vanilla of the most vanilla.  Its radular morphology was described by Thompson (1984).

Clappia umbilicata was originally described by Bryant Walker (1904) as Somatogyrus umbilicata from the Coosa River at Wetumpka, Alabama.  In 1909 he described his new genus Clappia and redescribed his S. umbilicata as "Clappia clappi."  So although Walker's genus remains valid today, the specific nomen "clappi" was born a junior synonym of umbilicata.  Tut-tut Bryant, you should have known better.

> Supplementary Resources

> Essays

  • The rediscovery of a Clappia population in the Cahaba River of Alabama was featured in my post to the FWNGA blog of 9May05, "Ivory-billed Freshwater Gastropods."
  • I reviewed the taxonomic history of the genus Clappia in my post of 9Nov12, "Bryant Walker's Sense of Fairness."
  • Additional details regarding our discovery of this obscure species in the Powell and Sequatchie drainages are available in my blog post of 3Dec12, "On Getting Clappia in Tennessee."  See also the helpful figure comparing Clappia to Amnicola, Somatogyrus, and juvenile Leptoxis.
  • 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

Dillon, R.T., Jr. (2000) The Ecology of Freshwater Molluscs. Cambridge University Press, Cambridge, United Kingdom. 
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. 
Thompson, F. (1984) North American freshwater snail genera of the hydrobiid subfamily Lithoglyphinae.  Malacologia 25: 109-141.
Walker, B.  (1904)  New species of Somatogyrus.  Nautilus 17: 133-142.
Walker, B.  (1909)  New Amnicolidae from Alabama.  Nautilus 22: 85 - 90. 
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.