A Review of the North American Freshwater Snail Genus Pyrgulopsis

NUMBER 554 63
units; Dg3 small (sometimes absent), borne on pronounced
proximal lobule. Dorsal penis also sometimes ornamented
with 1-3 small glandular dots centrally and/or along near right
side. Terminal gland elongate, transverse, slightly curved,
borne along distal edge (mostly on ventral surface). Ventral
gland borne on swelling near base of filament (gland
sometimes absent), sometimes with adjacent glandular dot
Filament dark.
Femalia genitalia are shown in Figure 5/. Ovary, 1 whorl,
overlapping posterior stomach chamber. Pallial albumen gland
short or absent. Capsule gland as long as albumen gland.
Genital aperture a terminal slit with vestibule. Coiled oviduct
of two overlapping horizontal loops positioned slightly behind
pallial wall. Oviduct and bursal duct join just behind pallial
wall. Bursa copulatrix ovoid, posterior end often blunt, long
(67%), broad (58%), with 33%-67% of length posterior to
albumen gland. Bursal duct relatively narrow, short Seminal
receptacle pouch-like, broad, short, overlapping anterior bursa
copulatrix, extending to posterior edge of albumen gland.
TYPE LOCALITY.—Jackson Lake, Wyoming. Holotype presumably
in UMMZ collection (could not be found).
DISTRIBUTION.—Jackson Lake and Polecat Creek (tributary),
northwest Wyoming, Snake River drainage.
REMARKS.—This snail is similar to other large-sized species
from southeast Oregon (P. hendersoni) and Snake River (P.
idahoensis). It differs in its weaker ventral operculum callus,
pointed central cusp on central radular tooth, presence of
anterior capsule gland vestibule, and broad bursa copulatrix.
MATERIAL EXAMINED.—USNM 874185, Polecat Creek,
Teton County, Wyoming (T 48N, R 115W, NE1/4 sec. 20).
Pyrgulopsis roswellensis (Taylor, 1987), new combination
Fontelicella roswellensis Taylor, 1987:14, fig. 6.
"Fontelicella" roswellensis—-USDL 1991b:58819.
DIAGNOSIS.—Shell ovate-conic, medium to large-sized,
weakly umbilicate. Penial filament medium length, lobe short
Penial ornament an elongate, sometimes proximally bifurcate
penial gland; small Dg2, sometimes absent; small Dg3,
sometimes absent, borne on low swelling; curved, transverse
terminal gland; and ventral gland.
DESCRIPTION.—Shell (Figure 24g) ovate-conic; height,
2.4-3.8 mm; whorls, 4-5. Protoconch finely punctate. Teleoconch
whorls slightly-moderately convex, often strongly
shouldered; sculpture of weak-moderate growth lines. Aperture
adnate to slightly separated from body whorl. Inner lip
complete, thickened; columellar lip reflected. Outer lip slightly
prosocline. Umbilicus very narrowly rimate to shallowly
perforate. Periostracum light tan.
Operculum (Figure 2Ah,i) ovate, amber, sometimes with
internal calcareous smears; nucleus slightly eccentric; dorsal
surface weakly frilled. Attachment scar margin thickened all
around, broadly so along inner edge and between edge and
nucleus; callus well developed.
Central radular tooth (Figure 39c/) with moderately indented
dorsal edge; lateral cusps, 5-6; central cusp pointed, considerably
longer, slightly broader than laterals; basal cusps, 1,
narrowly elongate, with strong dorsal support Basal process
narrow; basal sockets deep. Lateral margins thickened; neck
pronounced.
Cephalic tentacles light-moderate brown. Snout moderatedark
brown. Foot dark along anterior and posterior edges,
variably pigmented along sides. Opercular lobe margins dark,
especially anterior edge; central region variably pigmented.
Neck pale to light brown. Pallial roof, visceral coil dark
brown-black.
Ctenidial filaments, 18, tall, narrow. Osphradium centered
slightly posterior to middle of ctenidial axis. Kidney opening
white. Stomach caecum small.
Testis, 1.25 whorls, completely overlapping posterior stomach
chamber. Prostate gland with large (31%) pallial section;
pallial vas deferens with proximal kink. Penis (Figure 50e)
large; base narrowly rectangular; filament medium length,
strongly tapered; lobe short, slightly narrower than base. Penial
gland covering most of filament, sometimes bifurcate proximally.
Dg2 small, horizontal, sometimes absent Dg3 small,
borne on low swelling near base of lobe (gland, swelling
sometimes absent). Terminal gland transverse, curved, borne
along distal edge, mostly on ventral surface. Ventral gland
borne on swelling near base of filament; glandular dot
sometimes present proximal to above. Filament pale to darkly
pigmented.
Ovary, 0.75 whorl, overlapping posterior stomach chamber.
Albumen gland with large (28%) pallial section. Capsule gland
slightly shorter than albumen gland. Genital aperture a terminal
slit without vestibule. Coiled oviduct a slight horizontal twist
followed by broad horizontal loop (kinked at mid-point)
slightly behind pallial wall. Oviduct and bursal duct join just
behind pallial wall. Bursa copulatrix ovoid-pyriform, posterior
end rounded, long (60%), as broad as albumen gland, with
70%-83% of length posterior to albumen gland. Bursal duct
short, narrow. Seminal receptacle sac-like, stubby, short,
overlapping anterior bursa copulatrix, extending to posterior
edge of albumen gland.
TYPE LOCALITY.—Seepage 1250 ft E, 2100 ft S, sec. 21,
T10S, R25E, Chaves County, New Mexico. Holotype, LACM
2213; paratypes, UTEP 10057.
DISTRIBUTION.—Pecos River drainage, central New Mexico.
REMARKS.—Amongst species of Pyrgulopsis, only this snail
and P. metcalfi and P. davisi have a proximally bifurcate penial
gland. Pyrgulopsis roswellensis is distinguished from these two
species by its weak development of dorsal glands and small
bursa copulatrix.
MATERIAL EXAMINED.—USNM 873132, unnamed spring,
Roswell Country Club, Chaves County, New Mexico (T 10S, R
24E, SE1/4 sec. 22).