Image Usage Information
Family: Helicodiscidae
Common name: Smooth Coil
Discovery: Pilsbry, 1889
Identification
Width: 2-2.5 mm
Height: ~1 mm
Whorls: 3+
The tiny, fragile, translucent shell of Lucilla singleyana has a glossy surface marked by growth wrinkles and some additional radial grooves. Under high magnification, very faint spiral lirae may become apparent. The open umbilicus is about one-third the diameter of the entire shell, and the aperture is about the same size as the umbilicus.
In eastern Europe where this species and its relative L. scintilla are introduced, they are distinguished by shell color, size, and shape (Horsák et al, 2009). The shell of Lucilla scintilla is whitish, larger and taller than L. singleyana. Both Lucilla species have a smooth and glossy shell surface, while Hawaiia species exhibit a crosshatch of fine striae.
Ecology
Lucilla singleyana prefers open land, including dry grasslands, bare rock and talus, roadsides, and urban terrain (Nekola, 2009).
Taxonomy
Synonyms for Lucilla singleyana include Helicodiscus singleyanus, Helicodiscus (Hebetodiscus) singleyanus singleyanus, Hyalinala eviuscula, H. texana, Zonites singleyanus, and Zonitoides singleyanus.
Distribution
This animal is known from much of the northeastern and midwestern United States. In Virginia it is reported from only a few mid-western counties.
Conservation
NatureServe Global Rank: G5, Secure.
NatureServe State Rank: Virginia, S2S4, Imperiled to Apparently Secure.
