> Habitat & Distribution

This species is known only from Lake Waccamaw, Columbus County, North Carolina, and its tributary Big Creek (SCFTM 1990). Porter (1985) reported an average density of 273 per square meter in the lake, reaching maximum abundance in shallow, sandy regions with emergent vegetation.  Population densities seem much reduced more recently, however.  (See my blog post of 16July10 from the link below for more.) FWGNA incidence rank I-2, rare.

> Ecology & Life History

Hydrobiids seem to be rather nonspecific grazers of small particles (Dillon 2000: 94-97).  The laboratory feeding experiments of Schultheis & Kellmann (2013) showed that a mixed diet of the yellow-green filamentous Vaucheria and the blue-green filamentous Lyngbya was superior to either alga in pure diet for Floridobia floridana.  

Hydrobioids are (almost) universally dioecious, the males being characterized by a penis that arises from the neck.  Females attach single eggs in spare, hemispherical capsules to solid substrates (Hershler 1994).

> Taxonomy & Systematics

Like Spilochlamys, Notogillia, and Marstonia, the genus Floridobia belongs to the subfamily Nymphophilinae of the Hydrobiidae (ss), males being characterized by a lobe-shaped penis (or verge) with surficial glandular patterns.  The Floridobia penis has crescent-shaped terminal and ventral glands on its large terminal penial lobe and a slender flagellum (Kabat and Hershler 1993, Thompson 1968, 2004).

The genus Floridobia has only recently been distinguished from Cincinnatia, on the basis of female reproductive anatomy (Thompson & Hershler 2002).  There are three (nominal) species in our study area - Floridobia floridana (ranging through Florida into southern Georgia) and two apparently undescribed species, one in the Ocmulgee River and this second inhabiting Lake Waccamaw.  

Interestingly, the mtDNA survey of Hershler et al. (2003) revealed little differentiation between Floridobia and the (primarily western) hydrobiid genus Pyrgulopsis.  The difference between Floridobia and Marstonia seems to be more pronounced.

> Maps and Supplementary Resources

• Floridobia distribution in Atlantic drainages (2023)

> Essays

• The Waccamaw population of Floridobia was mentioned prominently in my blog post of 16July10, "Crisis at Lake Waccamaw." 
• Conservation-biased oversampling of the Waccamaw Floridobia population was featured in my blog post of 19Mar12, "Toward the Scientific Ranking of Conservation Status - Part III."
• 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. 
Hershler, R. (1994)  A review of the North American freshwater snail genus Pyrgulopsis (Hydrobiidae). Smithsonian Contributions to Zoology 1994; 0(554):1-115.    
Hershler, R., H. Liu, and F.G. Thompson (2003)  Phylogenetic relationships of North American nymphophiline gastropods based on mitochondrial DNA sequences.  Zoologica Scripta 32:357-366.    
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.  
Porter, H. J. (1985) Molluscan census and ecological interrelationships. Rare and endangered fauna of Lake Waccamaw, North Carolina watershed system. NC Endangered Species Restoration Final Report, 1978-1981. NCWRC report. 
Schultheis, A. S. & C. R. Kellmann (2013)  Cyanobacteria-rich diet reduces growth rates of the hyacinth siltsnail Floridobia floridana (Gastropoda: Hydrobiidae)  Walkerana 16: 1 - 8.
Scientific Council on Freshwater and Terrestrial Mollusks. (1990) (W. F. Adams, Chair) A report on the conservation status of North Carolina's freshwater and terrestrial molluscan fauna.
Thompson, F.G. (1968)  The Aquatic Snails of the Family Hydrobiidae of Peninsular Florida. University of Florida Press, Gainesville, Florida, USA.  
Thompson, F.G. (2004)  An identification manual for the freshwater snails of Florida.  
Thompson, F. G. & R. Hershler (2002)  Two genera of North American freshwater snails: Marstonia Baker, 1926, resurrected to generic status, and Floridobia, new genus (Prosobranchia: Hydrobiidae: Nymphophilinae).  The Veliger 45: 269 - 271.
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.