Land Snails

Photo(s): Vertigo alabamensis, not yet reported from Virginia, shell image © Jeff Nekola.

Click photo(s) to enlarge.

Vertigo alabamensis (Clapp, 1915) (not yet reported)

Family: Vertiginidae
Common name: Alabama Vertigo

Identification
Height: ~1.8 mm
Width: ~0.9 mm
Whorls: 5

Only this species and V. clappi possess an upper palatal lamella that is roughly parallel to the lower apertural margin, allowing its long axis to be seen from the front. The shell of Vertigo alabamensis differs from that of V. clappi, however, in its ovoid shape, closed umbilicus, and presence of a strong calcified callus on the apertural margin.

Some individuals with fatter shells and smaller lamellae (equating to V. conecuhensis of Hubricht, 1985), may be found throughout the range of V. alabamensis. No difference has been noted in their DNA sequences (Nekola, unpublished data), so they can be simply considered a shell form of V. alabamensis.

Ecology
Vertigo alabamensis is an acid-loving (acidophilic) animal that lives in well-decomposed leaf litter, typically caught against low growing shrubs and vines in mesic pineland, pine-wiregrass savanna, and bay forest. It also displays a high degree of seasonality, with all individuals hatching in early spring and coming to adult age from late April to early June.

Taxonomy
Synonyms for this animal’s name include Vertigo alabamensis conecuhensis and Vertigo conecuhensis

Distribution
Known from only a single early 1900s collection from Tuscaloosa County, Alabama (Pilsbry, 1948; Hubricht, 1985), this species has been recently found across the southeastern coastal plain, from Mobile Bay and northern Florida north to the Albemarle-Pamlico Peninsula on the outer coastal plain of North Carolina. It went unnoticed for almost a century for two reasons – its acidic habitats were overlooked because it was assumed that no land snail could live there, and because old shells rapidly dissolve in such habitats, so surveys outside the brief period of abundance locate few (if any) shells.

This species has not yet been reported from Virginia. However, given its presence in the adjacent North Carolina coastal plain, it should be sought in acidic pocosins, pinelands, and oak forests in the Dismal Swamp region. It may also occur in the counties east of the Chesapeake Bay.

Even though Vertigo alabamensis is more common than once thought, the species remains of conservation concern. Populations can be readily eliminated by fire management, and the species is now absent from many seemingly appropriate sites that are subject to frequent prescribed burning.

NatureServe Global Rank: G3
NatureServe State Rank: none

 

Jeff Nekola 9/2012