A Review of the North American Freshwater Snail Genus Pyrgulopsis

NUMBER 554 21
Pratt (1977) recorded both "Fluminicola" avernalis and an
"undescribed species of Fontelicella" from Moapa Valley. It is
not clear from his abstract which of these two entities
corresponds to avernalis as recognized herein (no doubt the
other referring to Pyrgulopsis carinifera).
MATERIAL EXAMINED.—USNM 874000, USNM 874003,
Oasis Spring, Moapa Valley, Clark County, Nevada (T 14S, R
65E, sec. 16).
Pyrgulopsis bacchus Hershler, 1988
Pyrgulopsis bacchus Hershler in Hershler and Landye, 1988:21, figs. lOd,
lle-g, 12d-f, 14b, 15.
DIAGNOSIS.—Shell ovate-conic, medium-sized, umbilicate.
Penis small; filament medium length; lobe short, sometimes
bifurcate. Penial ornament a transverse, often fragmented
terminal gland.
DESCRIPTION.—Shell (Figure 9a) ovate-conic; height, 2.3-
3.1 mm; whorls, 4. Protoconch near smooth. Teleoconch
whorls convex, slightly to moderately shouldered; sculpture of
pronounced growth lines. Aperture ovate, large, narrowly
adnate to slightly separated from body whorl. Inner lip
complete, slightly thickened; columellar lip moderately reflected.
Outer lip slightly prosocline. Umbilicus perforate.
Periostracum light brown. Operculum (Figure 9b,c) ovate,
amber, nucleus slightly eccentric; dorsal surface weakly frilled.
Attachment scar margin slightly thickened along outer edge;
callus very weak.
Central radular tooth (Figure 32/) with strongly indented
dorsal edge; lateral cusps, 3-4; central cusp pointed, considerably
longer than laterals; basal cusps, 1, short, broadly
triangular, with moderate dorsal support. Basal process narrow;
basal sockets deep. Lateral margins thickened; neck moderate.
Cephalic tentacles pale or with light gray pigment patch
distal to eyespots. Snout moderate to dark gray-black. Foot pale
or lightly pigmented, with darkest area along anterior edge.
Opercular lobe dark along margins; neck usually pale. Pallial
roof, visceral coil pigment moderate-dark, often uniformly
black.
Ctenidial filaments, 20, tall, medium width. Osphradium
centered posterior to middle of ctenidial axis. Kidney with
pronounced (50%) bulge into pallial cavity; kidney opening
white. Stomach caecum medium-sized.
Testis, 2 whorls, overlapping stomach almost to style sac.
Prostate gland with short pallial section; pallial vas deferens
proximally kinked. Penis (Figure 43/) small, stout; base near
square; filament slightly shorter than base, broad; lobe short,
broader than base, sometimes bifurcate distally. Terminal gland
transverse, positioned along distal edge, often fragmented into
2-3 small units, usually with a largely ventral orientation.
Filament lightly pigmented.
Ovary, up to 0.5 whorl, very slightly overlapping posterior
stomach chamber. Pallial albumen gland short. Capsule and
albumen glands about equal in length. Genital aperture a
terminal slit without vestibule. Coiled oviduct a short horizontal
kink followed by broad horizontal loop. Oviduct and bursal
duct join underneath oviduct coil just behind pallial wall. Bursa
copulatrix ovoid, medium length and width, positioned near
ventral edge of albumen gland, with about 33% of length
posterior to gland. Bursal duct narrow, slightly shorter than
bursa copulatrix, partly embedded in albumen gland distally.
Seminal receptacle finger-like, usually folded, short, overlapping
anterior bursa copulatrix or (more commonly) proximal
bursal duct, positioned near ventral edge of albumen gland.
TYPE LOCALITY.—Grapevine Spring, Mohave County,
Arizona. Holotype, USNM 859037; paratypes, USNM 859038.
DISTRIBUTION.—Several springs in Grand Wash, northwest
Arizona, Colorado River drainage.
REMARKS.—This species shares with P. solus a penis having
a frequently bifurcated lobe ornamented solely by a terminal
gland. Pyrgulopsis bacchus differs by its stouter penial
filament, consistent presence of dorsal gland (sometimes
present in P. arizonae), absence of an anterior capsule gland
vestibule, broader bursa copulatrix, and ventral position of the
seminal receptacle.
MATERIAL EXAMINED.—USNM 847203 (topotypes).
Pyrgulopsis bernardina (Taylor, 1987)
Yaquicoccus bernardinus Taylor, 1987:34, fig. 16.—USDI, 1991b:58823.
Pyrgulopsis cochisi Hershler in Hershler and Landye, 1988:41, figs. 25d,
30h-k, 33,34.
DIAGNOSIS.—Shell narrowly conic, small, weakly umbilicate.
Penial filament elongate, lobe absent Penial ornament of
centrally positioned dorsal and ventral glands.
DESCRIPTION.—Shell (Figure 9d) narrow-conic; height,
1.3-1.7 mm; whorls, 3.25-4.0. Protoconch weakly punctate,
with several weak adapical spiral lines on later portion.
Teleoconch whorls convex, shouldered; sculpture of weakmoderately
strong growth lines. Aperture ovate, large, very
narrowly adnate or slightly separated from body whorl. Inner
lip complete, thin; columellar lip slightly reflected. Outer lip
near orthocline. Umbilicus usually narrowly rimate. Periostracum
light tan.
Operculum (Figure 9e,f) ovate, light amber, nucleus slightly
eccentric; dorsal surface weakly frilled. Attachment scar
margin moderately thickened between inner edge and nucleus
and along most of inner edge; callus weak.
Central radular tooth (Figure 33a) with strongly indented
dorsal edge; tooth face square; lateral cusps, 4-5, elongate;
central cusp pointed, slightly longer than laterals; basal cusps,
1, elongate, with modest dorsal support. Basal process medium
width; basal sockets deep. Lateral margins slightly thickened;
neck moderate.
Cephalic tentacles pale. Snout pale to moderate gray-black.
Foot usually pale, sometimes lightly pigmented along anterior
edge. Opercular lobe black along inner edge, sometimes dark
over entire surface. Neck pale. Pallial roof, visceral coil