> Goniobasis floridensis timidus Goodrich 1942
    
> Habitat & distribution
Populations of G. floridensis are widespread throughout the northern half of Florida and the Gulf drainages of Georgia (Clench & Turner 1956, Chambers 1980, Thompson 2004), in rivers, springs, and the nearshore regions of lakes with low to moderate current.  Hanley & Ultsch (1999) reported individuals on all available substrates, to depths of 1.5 meters, in waters with temperatures of 14 - 26 C and a pH of 7.55 - 8.45.

The occurrence of G. floridensis in Atlantic drainages of Georgia was not suspected until the population genetic survey of Dillon & Robinson (in review).  We have recently documented several populations of G. floridensis bearing weakly-sculptured shells inhabiting springs and springfed streams in the vicinty of Hawkinsville.  These populations were originally described as "Goniobasis mutabilis timidus" by Goodrich (1942).  But since mutabilis is a synonym of catenaria, we suggested that the subspecific nomen be transferred to G. floridensis. 

> Ecology & Life history
In peninsular Florida, eggs are laid from February to October, and are embedded in sand-grain matrices affixed to plants and hard objects (Chambers 1980).  Although there have been no detailed studies of G. floridensis life history, I imagine that two years are required for maturity, and that several years of iteroparous reproduction can be expected thereafter, as is the case for pleurocerids generally (Dazo 1965).  This is life cycle G of Dillon (2000: 156 - 162).

Hanley & Ultsch (1999) reported that G. floridensis grazes on algae and other periphyton, as is typical of pleurocerids generally.  Grazing by high densities of pleurocerids can have a significant impact on energy flow in streams (Dillon 2000: 86 - 91).

> Taxonomy & Systematics
Genetic divergence at allozyme-encoding loci among populations of G. floridensis from Florida and the Gulf drainages of Georgia has been characterized by Chambers (1978, 1980, 1990). The survey of Dillon & Robinson (in review) included one of the Chambers (1980) populations as a control, as well as samples of G. floridensis timidus from Mile Creek (on the southern edge of Hawkinsville) and a Flint River tributary near Vienna.  All three were quite similar genetically.  

Mihalcik & Thompson (2002) reported that the mitochondrial CO1 gene sequences of two timidus individuals sampled from the vicinity of Hawkinsville were very similar to individual G. floridensis sampled from tributaries of the Flint River ("induta") and Chatttahoochee River ("glarea").  They nonethless raised Goodrich's taxon to the specific level and recognized three subspecies beneath it, "Elimia" timida timida, E. timida exul, and E. timida nymphaea.  These are all synonyms of G. floridensis timidus.

Cytogenetic data have been reported by Chambers (1982) and Dillon (1989, 1991).  The diploid number is 2N = 36.

Burch resurrected the name "Elimia" to include catenaria and approximately 80 other pleurocerid species traditionally assigned to Goniobasis (Lea 1862).  But Elimia (H. & A. Adams 1854) is a composite group, explicitly rejected by Tryon, Walker, Pilsbry and Goodrich (Dillon 1989).  See essay below.

> Essay
See my 28Sept04 post to the FWGNA web site for a review of the Goniobasis/Elimia taxonomic controversy.

>Map of Goniobasis distribution (PDF)

> References
Chambers, S. M.  (1978)  An electrophoretically detected sibling species of "Goniobasis floridensis" (Mesogastropoda: Pleuroceridae).  Malacologia 17: 157-162.  Chambers, S. M. (1980)  Genetic divergence between populatons of Goniobasis (Pleuroceridae) occupling different drainage systems.  Malacologia 20: 63 - 81.  Chambers, S. M. (1982)  Chromosomal evidence for parallel evolution of shell sculpture pattern in Goniobasis.  Evolution 36: 113-120.  Chambers, S. M. (1990) The genus Elimia (= Goniobasis) in Florida (Prosobranchia: Pleuroceridae). Walkerana, 4, 237-70.  Clench, W. J. & R. D. Turner (1956)  Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwannee River.  Bull. Florida State Museum 1: 94 - 239.   Dazo, B. C. (1965)  The morpholoogy and natural history of Pleurocera acuta and Goniobasis livescens (Gastropoda: Cerithiacea: Pleuroceridae).  Malacologia 3: 1 - 80.    Dillon, R., T. Jr. (1989)  Karyotypic evolution in pleurocerid snails: I. Genomic DNA estimated by flow cytometry. Malacologia, 31: 197-203.  Dillon, R., T. Jr. (1991)  Karyotypic evolution in pleurocerid snails: II.  Pleurocera, Goniobasis and Juga.  Malacologia 33: 339 - 344.   Dillon, R. T., Jr. (2000)  The Ecology of Freshwater Molluscs. Cambridge, Cambridge University Press.  509 pp. Dillon, R. T., Jr. & Robinson, J. D. (in review) Genetic relationships among populations of Goniobasis ("Elimia") from central Georgia. Goodrich, C. (1942) The Pleuroceridae of the Atlantic coastal plain. Occas. Pprs. Mus. Zool. Univ. Mich., 456, 1-6.  Hanley, R.W. & G.R. Ultsch (1999)  Ambient oxygen tension, metabolic rate, and habitat selection in freshwater snails. Archiv Hydrobiologii 144:195-214.  Mihalcik, E. R. & F. G. Thompson (2002) A taxonomic revision of the freshwater snails referred to as Elimia curvicostata, and related species.  Walkerana 13: 1 - 108.   Thompson, F.G. (2004)  An identification manual for the freshwater snails of Florida.