This species was discovered and described under the name Somatogyrus umbilicatus by the American malacologistBryant Walker in 1904.[3] Walker's type description reads as follows:
Somatogyrus umbilicatus n. sp. Pl. v, fig. 5.
Shell small, globosely depressed, umbilicate, light greenish-yellow,
smooth, except for the fine, rather unequal, lines of growth. Spire
short, obtusely elevated. Whorls 3½ those of the spire convex and
separated by a well-impressed suture; body whorl large, gibbously
convex. Aperture sub-circular, rather longer than broad, obtusely
angled above and slightly flattened along the basal margin. Columella concave, narrowly reflected; columellar callus, moderately
heavy, rounded, reflected over but not concealing the round, deep umbilicus, thin and transparent on the parietal wall. Alt. 3, diam. 3 mm.
This species is remarkable for its depressed, valvata-like form and round, deep umbilicus, which readily differentiates it from all other known species of the genus. It does not appear to be very abundant at Wetumpka, and only a single example was collected at Fort Williams Shoals.
The color of Clappia umbilicata was black.[4] This presumably means that the whole animal including snout, nape, mantle and foot were black.[6] The black color of the mantle was verified by Thompson (1984).[6]
Clappia umbilicata has 56-59 rows of teeth on its radula.[6] Each row has 6-7 central basocones, 6-7 central ectocones, 18-21 lateral teeth, ca. 50 inner marginal teeth and ca. 35 outer marginal teeth.[6]
Ecology
The natural habitat of this species was rivers.[1]Clappia umbilicata inhabited only the rapidly flowing sections of river shoals.[6] The snail died out because of silting of its habitat after the dam was constructed in 1928.[1] (Also see Jordan Dam and Jordan Lake).
Based on examination of the radula, Thompson (1984)[6] hypothesized that Clappia umbilicata grazed on fine particles of plants, specializing on finer-sized particles than those consumed by snails in the genus Somatogyrus.[6]
^Kabat A. R. & Hershler R. (1993). "The prosobranch snail family Hydrobiidae (Gastropoda: Rissooidea): review of classification and supraspecific taxa". Smithsonian Contributions to Zoology547: 1-94. page 18. PDF.
^ abcdefghThompson F. G. (1984). "North American freshwater snail genera of the hydrobiid subfamily Lithoglyphinae". Malacologia25(1): 109-141.
^ abClench W. J. (1965). "A new species of Clappia from Alabama". The Nautilus79(1): 33-34. Figure 2.