\Length, 2.5 mm; angulo-parietal not bifid in frontal view.
Crest strong and placed well behind lip; surface flattened behind crest.
Angulo-parietal lamella not bifid, but with short spur on right side (appearing on left side from this view).
Notes:
Locality: Missouri,
Cedar Co., Stockton Lake State Park, [37° 37' 12"N, 93° 45' 57"W], from
dry soil at top of bluffs and rock outcrops along Stockton Lake, 10 specimens.
The simple form of angulo-parietal lamella is consistent among all specimens
in the lot. Otherwise, this species is very similar to Gastrocopta procera
(Gould, 1840).
Previously recorded from eastern Oklahoma to Laredo Texas and west to
Yavapai Co., Arizona (Pilsbry, 1948). Hubricht, 1985, notes additional
localities in western Arkansas, southern Louisiana and central to southerwestern
Kansas.
All of the eastern-most localities in Kansas, Oklahoma, Arkansas and Louisiana were from river-drift; most specimens are known from pleistocene or river-drift collections (Hubricht, 1985).
G. cristata has also been introduced into Maryland and Delaware (Hubricht, 1985).
The Missouri lot includes some live-collected specimens. Unless this population has been recently introduced, this may represent the northeastern-most, natural population.
References:
Pilsbry, 1948, LMNA pp. 911-913, fig. 493
6, 8-12
Hubricht, 1985, Dist. Nat. Land. Moll. E. US, p.
10, map 47