A Review of the North American Freshwater Snail Genus Pyrgulopsis

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
FIGURE 3.—Scanning electron micrographs of dorsal cephalic tentacles showing ciliation: a, Pyrgulopsis
arizonae, USNM 847226 (bar = 100 nm); b, P. micrococcus, USNM 847246 (bar = 176 Jim); c. P. lustrica, UF
22227 (bar = 200 Jim); d, P. californiensis, SBMNH uncat (scale as in b); e, P. micrococcus, ibid, (scale as in
£>);/, P. lustrica, ibid, (scale as in b).
positioned on posterior albumen gland, sometimes embedded
in albumen gland for part of or entire length. Seminal
receptacle ovate to elongate, often folded; usually positioned
posterior to coiled oviduct, along mid-line to near ventral side
of albumen gland, overlapping anterior bursa copulatrix and/or
proximal bursal duct. Seminal receptacle duct usually short,
narrow.
DISTRIBUTION.—Western North America, including Snake
River basin, Great Basin, California coastal drainages, Baja
California, Colorado River basin, Rio Grande basin, Pecos
River basin, and internal drainages of Northern Mexico;
Eastern North America, including Mississippi River basin,
Great Lakes drainage, Tennessee River basin, and coastal
drainages of Georgia (Figure 6).
FOSSIL RECORD.—Pyrgulopsis appears to date from the late
Tertiary of the western United States (Taylor, 1985, table 2),
although assignment of fossil forms to the genus is largely
conjectural.
REMARKS.—North American workers generally have maintained
Pyrgulopsis as a distinct genus, while Wenz (1926) and
Thiele (1929) treated it as a subgenus within Tryonia and
Hydrobia, respectively. Pyrgulopsis early was placed in the
subfamily Hydrobiinae (Thiele, 1929; Wenz, 1939; Taylor,
1966b) while Starobogatov (1970) later allocated the genus to
the Nymphophilinae, although without explanation. Thompson
(1979), in an important paper redefining the Nymphophilinae,
similarly (and apparently independently) suggested this placement,
although on a tentative basis given that he had not