A Review of the North American Freshwater Snail Genus Pyrgulopsis

NUMBER 554 69
DIAGNOSIS.—Shell ovate- to narrowly-conic, small to large,
weakly umbilicate. Penial filament short, lobe medium length.
Penial ornament a short penial gland, short Dg2, short Dg3
borne on low swelling, transverse terminal gland, and ventral
gland.
DESCRIPTION.—Shell (Figure 26g) ovate- to narrowly-conic;
height, 1.5-4.5 mm; whorls, 3.5-5.0. Early protoconch very
weakly punctate, later portion smooth or with faint spiral lines.
Teleoconch whorls slight-moderately convex, rarely shouldered;
sculpture of weak growth lines. Aperture usually adnate
to (rarely slightly separated from) body whorl. Inner lip
complete, thin; columellar lip often reflected. Outer lip slightly
prosocline. Umbilicus narrowly rimate (near absent) to weakly
perforate. Periostracum tan.
Operculum (Figure 26h,i) ovate, amber, nucleus highly
eccentric; dorsal surface smooth. Attachment scar margin
moderately thickened all around; callus moderate.
Central radular tooth (Figure 40rf) with moderate-highly
indented dorsal edge; lateral cusps, 5-6; central cusp pointed or
rounded, considerably broader and longer than laterals; basal
cusps, 1, medium-sized, with strong dorsal support. Basal
process medium width; basal sockets deep. Lateral margins
thickened; neck pronounced.
Cephalic tentacles, snout, foot pale or near pale to dark
brown. Opercular lobe pale or moderate-dark brown-black
along sides; inner edge sometimes with black internal streak.
Neck pale to moderate. Pallial roof, visceral coil, near-uniform
black.
Ctenidial filaments, 21, medium height, narrow. Osphradium
centered well posterior to middle of ctenidial axis.
Kidney opening white. Stomach caecum large.
Testis, 1.5 whorls, overlapping stomach almost to edge of
style sac. Prostate gland with large (25%) pallial section; pallial
vas deferens with proximal kink. Penis (Figure 51e) large;
filament short, broad; lobe slightly longer than filament,
tapered. Penial gland short, restricted to base of filament Dg2
short; Dg3 short, usually borne on weak swelling. Terminal
gland small, largely transverse, near straight, borne along distal
edge (largely ventral surface) of lobe. Ventral gland borne on
sub-terminal swelling; occasionally accompanied by smaller,
stalked gland proximal to above. Filament pale.
Ovary, 0.75-1.0 whorl, overlapping posterior stomach
chamber. Pallial albumen gland large (28%-33%). Albumen
gland longer than capsule gland. Genital aperture a subterminal
slit; vestibule absent or very short. Coiled oviduct a slight
horizontal kink followed by broad horizontal loop slightly
behind pallial wall. Oviduct and bursal duct join slightly behind
pallial wall. Bursa copulatrix ovoid, short to medium length
(38%-48%), medium width, with about 55% of length
posterior to gland. Bursal duct medium width, shallowly
embedded in albumen gland, medium length. Seminal receptacle
pouch-like, folded, long (60%), positioned lateral to or
overlapping anterior bursa copulatrix, extending to posterior
edge of albumen gland.
TYPE LOCALITY.—Pyrgulopsis trivialis: Spring-fed pond,
1,000 ft N of SW corner sec. 5, T5N, R29E, Apache County,
Arizona. Holotype, LACM 2225; paratypes, UTEP 10059,
ANSP 376022, FSM 160941, USNM 854080. Pyrgulopsis
confluentis: Spring on north side of Blanket Creek at Three
Forks, Apache County, Arizona (T 5N, R 29E, SE1/4 sec. 6).
Holotype, USNM 859053; paratypes, USNM 859054.
DISTRIBUTION.—Upper Black River drainage (tributary to
Gila River), southeast Arizona.
MATERIAL EXAMINED.—USNM 847234 (topotypes, confluentis).
Pyrgulopsis wongi Hershler, 1989
Pyrgulopsis wongi Hershler, 1989:196, figs. 41-47.—Hershler and Pratt,
1990:286, fig. 7.
DIAGNOSIS.—Shell globose to low-conical, small to medium-sized,
umbilicate. Penial filament and lobe medium
length. Penial ornament an elongate penial gland, curved Dgl,
Dg2, Dg3 borne on moderate swelling; elongate, transverse,
curved terminal gland; and two ventral glands. Dorsal glands
sometimes fused.
DESCRIPTION.—Shell (Figure 27a) globose to low-conical;
height, 1.2-3.0 mm; whorls, 3.25-4.5. Protoconch very
weakly punctate. Teleoconch whorls moderately convex,
shouldered; sculpture of weak growth lines. Aperture narrowly
adnate or slightly separated from body whorl. Inner lip
complete, usually thin. Outer lip orthocline or slightly
prosocline. Umbilicus narrowly rimate to perforate. Periostracum
tan.
Operculum (Figure 21b,c) broadly ovate, amber, with dark
central region; nucleus slightly eccentric; dorsal surface
smooth. Attachment scar margin moderately thickened all
around; callus moderate.
Central radular tooth (Figure 40e) with moderately indented
dorsal edge; lateral cusps, 4-7; central cusp pointed, usually
considerably broader and longer than laterals; basal cusps, 1,
medium-sized, with moderate dorsal support Basal process
narrow; basal sockets deep. Lateral margins thickened; neck
weak-absent
Cephalic tentacles, foot pale to moderate gray-black. Snout,
neck pale to dark gray-black. Opercular lobe pale to moderate
gray-black along sides and inner edge, occasionally black all
around (with central region light). Pallial roof, visceral coil
light-dark gray-black, sometimes uniformly dark.
Ctenidial filaments, 16, medium height and width. Osphradium
centered well posterior to middle of ctenidial axis.
Kidney opening white. Stomach caecum broad, crescentshaped.
Testis, 1 whorl, slightly overlapping posterior stomach
chamber. Prostate gland with short pallial section; pallial vas
deferens with proximal kink. Penis (Figure 51/) very large,
broad; filament medium length, tapered; lobe medium length,
with little or no taper distally. Penial gland covering most of