A Review of the North American Freshwater Snail Genus Pyrgulopsis

NUMBER 554 33
ornament an elongate, proximally bifurcate, penial gland;
transverse Dgl, short Dg2, Dg3 borne on raised swelling,
curved, transverse terminal gland, and ventral gland.
DESCRIPTION.—Shell (Figure \3g) ovate- to narrowly
conical; height, 2.7-3.9 mm; whorls, 4-4.5. Early protoconch
moderately punctate, later portion weakly punctate-smooth,
with a few abapical spiral lines. Teleoconch whorls moderately
to highly convex, shouldered; sculpture of moderate growth
lines. Aperture ovate, angled above, usually separated from
body whorl. Inner lip complete, thickened; columellar lip
slightly reflected. Outer lip near-orthocline. Umbilicus weakly
to moderately perforate. Periostracum light tan.
Operculum (Figure I3h,i) broadly ovate, amber, nucleus
slightly eccentric; dorsal surface smooth. Attachment scar
margin broadly thickened between nucleus and inner edge and
along most or all of length of latter, scar weaker or faint along
outer edge; callus very weak, but broad in extent
Central radular tooth (Figure 34/) with moderately indented
dorsal edge; lateral cusps, 4; central cusp rounded, elongate,
broader than laterals; basal cusps, 1, short, with moderate
dorsal support. Basal process narrow; basal sockets deep.
Lateral margins moderately thickened; neck pronounced.
Cephalic tentacles pale or with moderate gray-black pigment
proximally. Snout light to dark gray-black. Foot pale or dark
along anterior and posterior margins. Opercular lobe with dark
internal pigment along sides. Neck generally light, but
sometimes with dark internal pigment patch. Pallial roof,
visceral coil moderate to dark brown-black. Completely pale
individuals rare.
Ctenidial filaments, 20, narrow, short. Osphradium centered
posterior to middle of ctenidial axis. Kidney opening slightly
thickened. Stomach caecum medium-sized.
Testis, 1 whorl, very slightly overlapping posterior stomach.
Prostate an elongate bean-shape; pallial section large (>50%);
pallial vas deferens undulating along columellar muscle. Penis
(Figure 45e) large, extending beyond mantle edge; base near
square; filament medium length, broad, tapering distally; lobe
slightly shorter than filament, narrowing distally. Penial gland
elongate, bifurcating proximally. Dgl crossing about half of
penis width, stalked, positioned near mid-penis; Dg2 a narrow
strip; Dg3 borne on raised swelling. Dorsal penis sometimes
also with 1-2 additional small glands near distal edge. Terminal
gland elongate, transverse, slightly curved, borne along distal
(largely ventral surface) edge of lobe. Ventral gland prominent,
stalked, positioned near distal edge; small glandular dot
sometimes present slightly proximally to above. Filament with
scattered dark granules.
Ovary, 0.5 whorl, extending to posterior edge of stomach.
Pallial albumen gland short. Capsule gland slightly shorter than
albumen gland. Genital aperture a broad terminal pore with
short vestibule. Coiled oviduct a slight kink followed by broad
horizontal loop extending to pallial wall. Oviduct and bursal
duct join at pallial wall. Bursa copulatrix ovoid, medium
length, broad (66%), with most of length (75%) posterior to
albumen gland. Bursal duct narrow, about half of length of
bursa copulatrix. Seminal receptacle sac-like, short, overlapping
anterior bursa copulatrix.
TYPE LOCALITY.—Tributary of Limpia Creek about 5 mi (8
km) northeast of Fort Davis, Jeff Davis County, Texas.
Holotype, LACM 2211; paratypes, UTEP 10053, ANSP
376023, FSM 160944, USNM 854085.
DISTRIBUTION.—Thus far known only from the type locality
(Pecos River drainage) although dry shell collections suggest
that it may also occur at a few other local sites (Taylor, 1987).
REMARKS.—This snail differs from similar P. metcalfi by its
stronger ventral operculum callus, circular oviduct coil, dorsal
position of bursal duct, and ventral position of seminal
receptacle.
MATERIAL EXAMINED.—USNM 873427 (topotypes).
Pyrgulopsis deserta (Pilsbry, 1916)
Amnkola deserta Pilsbry, 1916:111, figs. 8, 9.—Walker, 1918:133.—Baker,
1964:172.
"Amnicola" deserta.—Landye, 1981:70.
Fontelicella deserta.—Taylor, 1975:73.—Burch, 1982:26, fig. 237—Tbrgeon
etal., 1988:61.
Pyrgulopsis deserta.—Hershler and Thompson, 1987:29.—Hershler and
Landye, 1988:17, figs. 10c, lla-d, 12a-c, 13.
DIAGNOSIS.—Shell globose to ovate-conic, small to medium-sized,
umbilicate. Penial filament medium length, lobe
short. Penial ornament an elongate penial gland, near-circular
terminal gland, and ventral gland.
DESCRIPTION.—Shell (Figure 14a) globose to ovate-conic;
height, 1.2-2.4 mm; whorls, 3.5-4.25. Early protoconch
moderately punctate, otherwise near smooth. Teleoconch
whorls very slightly to highly convex, very weakly to strongly
shouldered; sculpture of weak growth lines. Aperture angled
above, broadly adnate to slightly separated from body whorl.
Inner lip complete, thickened; columellar lip slightly reflected.
Outer lip usually prosocline. Umbilicus narrowly rimate (rarely
absent) to broadly perforate. Periostracum light brown.
Operculum (Figure \4b,c) ovate, light amber, nucleus slightly
eccentric; dorsal surface weakly frilled. Attachment scar
margin moderately thickened along inner edge (nuclear half) to
nucleus; scar faint to absent along outer edge; callus weakabsent.
Central radular tooth (Figure 35a) with strongly indented
dorsal edge; lateral cusps, 4-6, narrowly elongate; central cusp
pointed, considerably longer than laterals; basal cusps, 1, short,
with moderate dorsal support Basal process narrow; basal
sockets deep. Lateral margins thickened; neck moderate.
Cephalic tentacles pale to moderate brown, sometimes with
conspicuous pigment patch just distal to eyespots. Snout pale to
dark brown-black; foot similarly pigmented, usually lighter in
central region. Opercular lobe pale or with dark streak along
inner edge. Neck pale to lightly pigmented. Pallial roof pale to
dark; visceral coil moderate-dark, sometimes uniformly black.
Ctenidial filaments, 10, medium height, narrow. Osphra-