A Review of the North American Freshwater Snail Genus Pyrgulopsis

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DIAGNOSIS.—Shell ovate- to narrowly-conic, medium to
large-sized, weakly umbilicate. Penial filament medium length;
lobe short, oblique. Penial ornament a transverse terminal
gland.
DESCRIPTION.—Shell (Figure 27g) ovate to narrowly conic;
height, 3.2-3.9 mm; whorls, 5; generally thickened and often
whitened. Early protoconch strongly punctate adapically,
otherwise near smooth. Teleoconch whorls weakly convex,
slightly shouldered; sculpture of weak growth lines and
occasional faint spiral striae. Aperture broadly ovate, moderately
large, narrowly adnate to or slightly separated from body
whorl. Inner lip complete, thickened; columellar lip sometimes
slightly reflected. Outer lip usually thickened, often with broad
internal ridge, sinuate (advanced abapically). Umbilicus
weakly rimate or absent. Periostracum light brown.
Operculum (Figure 21h,i) ovate, light amber, slightly
indented along outer edge; nucleus highly eccentric. Dorsal
surface smooth. Attachment scar margin moderately thickened
between nucleus and inner edge; callus moderate.
Central radular tooth (Figure 4\b) with moderately indented
dorsal edge; lateral cusps, 4; central cusp pointed, considerably
longer and slightly broader than laterals; basal cusps, 1 (second,
rudimentary outer cusp sometimes present), short, broad, with
weak dorsal support. Basal process tongue-shaped; basal
sockets deep. Lateral margins thickened; neck weak-absent
Snout, neck unpigmented or light brown. Cephalic tentacles,
foot, opercular lobe unpigmented. Pallial roof with prominent
narrow brown streaks along margins of ctenidium (often
connected anteriorly) and sometimes along dorsal edge of
glandular oviduct (occasionally as broad bands covering entire
dorsal surface of structure). Dorsal testis often dark brown,
visceral coil otherwise unpigmented.
Ctenidial filaments, 28, tall, narrow. Osphradium centered
posterior to middle of ctenidial axis. Kidney with slight bulge
into pallial cavity; opening white. Caecum of stomach large,
broadly triangular.
Testis, 1.25-1.5 whorls, overlapping stomach to posterior
edge of style sac. Prostate gland thickened, with large (40%)
pallial section; vas deferens opening from near anterior end of
prostate gland, pallial section with several tight loops. Penis
(Figure 526) large, extending well beyond mantle edge;
filament medium length, thickened, with pointed tip; lobe
short, broad, oblique. Terminal gland transverse, borne along
distal edge of lobe. Filament sometimes darkly pigmented
internally.
Ovary, 1 whorl, overlapping posterior stomach. Pallial
albumen gland large (33%). Capsule gland as long as albumen
gland. Genital aperture a short, terminal slit with vestibule.
Coiled oviduct a proximal twist followed by narrow vertical
loop just behind pallial wall. Oviduct and bursal duct join
anterior to loop in posterior pallial cavity. Bursa copulatrix
ovoid, long (60%), about half as broad as albumen gland, with
about 50% of length posterior to gland. Bursal duct broad
posteriorly, narrowing anteriorly, largely embedded in albumen
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
gland, slightly shorter than bursa copulatrix. Seminal receptacle
pouch-like, short, positioned lateral to proximal bursal duct
along ventral edge of albumen gland.
TYPE LOCALITY.—Guntersville Reservoir, at mouth of Mint
Creek, 9.8 mi. (15.8 km) southwest of Scottsboro, Jackson
County, Alabama. Holotype, FSM 22286; paratypes, FSM
22287.
DISTRIBUTION.—Tennessee River drainage, northeast Alabama
and southeast Tennessee (Thompson, 1977, fig. 8).
REMARKS.—This snail is distinguished from other eastern
forms by its highly reduced penial lobe and medium length
bursal duct.
MATERIAL EXAMINED.—FSM uncat. (paratypes).
Pyrgulopsis castor (Thompson, 1977)
Marstonia castor Thompson, 1977:130, figs. 3c, 4h, 21, 22, 25e.—Burch,
1982:27, figs. 216, 234.—Tuigeon et al., 1988:61.
Pyrgulopsis castor.—Hershler and Thompson, 1987:29.—USDI,
1991b:58821.
DIAGNOSIS.—Shell ovate-conic, small to medium-sized,
umbilicate. Penial filament medium length, lobe short. Penial
ornament a horizontal terminal gland, and ventral gland.
DESCRIPTION.—Shell (Figure 28a) ovate-conic; height,
1.9-2.7 mm; whorls, 4.0-4.5. Early protoconch (Figure le)
strongly punctate adapically, later portion smooth. Teleoconch
whorls moderately convex, shouldered; sculpture of faint
growth lines. Aperture ovate, slightly angled above, narrowly
adnate or slightly separated from body whorl. Parietal lip
usually incomplete; in a few large specimens lip complete,
moderately thick; columellar lip slightly reflected. Outer lip
prosocline, often with thickened internal callus. Umbilicus
narrowly perforate. Periostracum light brown.
Operculum (Figure 2%b,c) ovate, very thin, light amber,
slightly indented along outer edge; nucleus slightly eccentric.
Dorsal surface weakly frilled. Attachment scar margin smooth
except for slight thickening along inner edge; callus nearabsent.
Central radular tooth (Figure 41c) with moderately indented
dorsal edge; lateral cusps, 4; central cusp pointed, slightly
longer and broader than laterals; basal cusps, 1 (sometimes
accompanied by small or rudimentary outer cusp), long, with
weak dorsal support. Basal process of medium width and
excavated. Lateral margins thickened; neck weak-absent
Cephalic tentacles, foot, neck unpigmented. Snout pale or
light brown. Opercular lobe with dark internal pigment along
anterior edge. Pallial roof with prominent dark brown pigment
streaks along margins of ctenidium; dorsal edge of glandular
gonoducts with weaker streaks. Gonads light to dark brown.
Ctenidial filaments, 20, tall, medium width. Osphradium
large (45%), extending almost to posterior end of ctenidium.
Kidney with prominent (50%) bulge into pallial cavity;
opening white. Caecum of stomach prominent, triangular.
Testis, 1 whorl, overlapping posterior stomach. Prostate