A Review of the North American Freshwater Snail Genus Pyrgulopsis

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DISTRIBUTION.—Endemic to type locality, Tennessee River
drainage (Thompson, 1977, fig. 8).
REMARKS.—Among Eastern American species, this snail
shares with several species a weak penial lobe. It differs from
other members of this fauna by the broad central cusp of central
radular tooth, posterior-oblique shape of oviduct coil, broad
bursa copulatrix, and largely posterior position of bursa
copulatrix.
MATERIAL EXAMINED.—FSM 146697 (topotypes).
Pyrgulopsis olivacea (Pilsbry, 1895)
Amnicola olivacea Pilsbry in Sargent, 1894a: 121 [nomen nudum].—Sargent,
1894b:95.
Amnicola olivacea Pilsbry, 1895a:l 15.—Walker, 1918:135.—Baker,
1964:174.
Marstonia olivacea.—Stein, 1976:26.—Thompson, 1977:122, fig. Id.—
Burch, 1982:27, fig. 247.—Turgeon et al., 1988:61.
Pyrgulopsis olivacea.—Hershler and Thompson, 1987:30.—USDI,
1991b:58822.
DIAGNOSIS.—Shell ovate-conic, large, variably umbilicate.
Penial filament, lobe very short. Penial ornament a terminal
gland.
DESCRIPTION.—Shell (Figure 29g) ovate-conic; height,
3.9-4.5 mm; whorls, 5.0-5.4. Protoconch moderately punctate
over most of length; later portion lined with several strong
spiral lines. Teleoconch whorls highly convex, shouldered;
sculpture of weak growth lines and fine spiral striations.
Aperture ovate, adnate to body whorl. Inner lip usually
complete, thin. Outer lip prosocline. Umbilicus narrowly to
broadly perforate. Periostracum brown.
Operculum (Figure 29h,f) thin, amber, outer edge strongly
indented; nucleus slightly eccentric; dorsal surface strongly
frilled. Attachment scar margin slightly thickened along most
of length, early whorl outlines bulging slightly above ventral
surface; callus very weak.
Central radular tooth (Figure 42b) with moderately indented
dorsal edge; lateral cusps, 3-4; central cusp rounded, slightly
longer and broader than laterals; basal cusps, 1 (with faint
suggestion of second, outer cusp), short, narrowly triangular,
with weak dorsal support. Basal process narrow; basal sockets
deep. Lateral margins thickened; neck absent.
Animal black.
Penis medium-sized; filament very short, stockly; lobe about
as long as filament, broadly triangular. Terminal gland borne
along distal edge of lobe (ventral side). Filament dark; black
granules also scattered on distal penis.
TYPE LOCALITY.—Huntsville, Alabama. Lectotype (Baker,
1964:174), ANSP 65466; paralectotypes, ANSP 396952.
DISTRIBUTION.—Known only from type locality, Tennessee
River drainage (Thompson, 1977, fig. 15), where it is now
extinct (Thompson, 1977).
REMARKS.—This snail resembles widely disjunct P. lustrica
in shape of shell and penis, but differs in having strong spiral
lines on the teleoconch.
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
Extralimital collections referred to by Goodrich (1939,1944)
probably were misidentified (fide Thompson, 1977).
Pyrgulopsis ozarkensis Hinkley, 1915
Pyrgulopsis ozarkensis Hinkley, 1915:588. pi. 78: fig. 2.—Walker, 1918:
140.—Burch, 1982:28.—Hershler and Thompson, 1987:30.—Turgeon etal.,
1988:62.—USDI, 1991b:58822.
Marstonia ozarkensis.—Gordon, 1986:76.
DIAGNOSIS.—Shell narrowly conic, medium-sized, variably
umbilicate. Animal unknown.
DESCRIPTION.—Shell (Figure 30a) narrowly conic; height,
2.5-3.0 mm; whorls, 5. Protoconch blunt, strongly punctate
near apex, usually slightly eroded, Teleoconch whorls weakly
convex, body whorl often with angulation or weak keel below
periphery; sculpture of weak growth lines and sometimes faint
spiral lines. Aperture ovate, broadly adnate to or slightly
separated from body whorl. Inner lip complete, moderately
thick; columellar lip slightly reflected. Outer lip moderately
thick, orthocline. Umbilicus absent to rimate. Periostracum
olive-tan.
TYPE LOCALITY.—North Fork of White River, 2 or 3 miles
(3.2-4.8 km) above Norfolk, Arkansas. Holotype, USNM
271765; paratypes, USNM 860581, ANSP 115102.
DISTRIBUTION.—Known only from the type locality, Mississippi
River drainage. A limited survey of this region in
1991-1992 did not yield this species.
REMARKS.—This species is similar to P. scalariformis, but
has a wider shell without basal carina.
Pyrgulopsis pachyta (Thompson, 1977)
Marstonia sp.—Stein, 1976:26.
Marstonia pachyta Thompson, 1977:121, figs. 3a, 12, 13.—Burch, 1982:27,
figs. 221,253—Turgeon etal., 1988:61.
Pyrgulopsis pachyta.—Hershler and Thompson, 1987:30.—USDI,
1991b:58822.
DIAGNOSIS.—Shell ovate-conic, medium to large-sized,
weakly umbilicate. Penial ornament a dorsal gland borne along
left distal edge; near-circular terminal gland, and ventral gland.
DESCRIPTION.—Shell (Figure 30ft) ovate-conic; height,
3.3-4.0 mm; whorls, 5. Earliest protoconch strongly punctate
adapically (Figure If). Teleoconch whorls weakly convex,
slightly shouldered; sculpture of strong growth lines and faint
spiral striae. Aperture usually broadly adnate to body whorl.
Inner lip complete, thickened, especially adapically. Outer lip
thick, slightly prosocline. Umbilicus imperforate to narrowly
rimate. Periostracum light brown.
Operculum (Figure 30c,d) ovate, light amber, nucleus highly
eccentric; dorsal surface slightly frilled. Attachment scar
margin slightly thickened between nucleus and inner edge,
weak-smooth elsewhere; callus moderate.
Central radular tooth (Figure 42c) with moderately indented
dorsal edge; lateral cusps, 4-5; central cusp weakly pointed,
tongue-like, broader and longer than laterals; basal cusps, 1,