Pyrgulopsis pilsbryana ( Baily & Baily, 1952 )

Perez, Kathryn E., Solis, Megan, Flores, Michelle & Lundskog, Chanté, 2025, Integrative taxonomy confirms the synonymy of three springsnail species (Hydrobiidae: Pyrgulopsis), European Journal of Taxonomy 997, pp. 144-179 : 158-163

Pyrgulopsis pilsbryana ( Baily & Baily, 1952)

Figs 8–11

Paludestrina longinqua Pilsbry, 1899: 122 (in part).

Amnicola pilsbryana Baily & Baily, 1952: 144 [new name for above].

Pyrgulopsis nonaria Hershler, 1998: 125–127 , figs 10i, 25g, 48a–c. Syn. nov.

Pyrgulopis transversa Hershler, 1998: 129–130 , figs 10j, 25h, 48d–f. Syn. nov.

Paludestrina longinqua – Stearns 1901: 285 (in part). — Henderson & Daniels 1917: 58–59. —

Henderson 1924: 190; 1931: 110.— Chamberlain & Jones 1929: 177 (in part). Amnicola pilsbryi – Baily & Baily 1952: 50–51, pl. 4 fig. 3. — Baker 1964: 175. Amnicola pilsbryana – Taylor 1965: 599. Fontelicella pilsbryana – Gregg & Taylor 1965: 108. — Taylor 1975: 152. — Burch 1982: 26. —

Turgeon et al. 1998: 61. Pyrgulopsis pilsbryi – Hershler & Thompson 1987: 30. Pyrgulopsis pilsbryana – Hershler 1994: 60, figs 23g –i, 39a, 50b. Pyrgulopsis pilsbryana “Lineage A ” – Liu et al. 2018: 107.

Original description

“This species is narrowly umbilicate, conic, smooth, with about four and a half very strongly convex whorls. The suture is deeply impressed. The aperture occupies about 40% of the length and is of a broadly oval shape, noticeably oblique. The columellar margin is slightly expanded. Length 3.0 mm, diameter 1.8 mm.”

Material examined

UNITED STATES OF AMERICA – Idaho • Spring, Saint Charles Canyon, Saint Charles Campground ; 42.11° N, 111.45° W; 12 May 1990; R. Hershler leg.; USNM 858281 . – Utah • Vernon Reservoir, Tintic Valley , 0.38 km upstream of reservoir; 39.98356° N, 112.38211° W; 1 Nov. 2022; K. Purington leg.; ANSP 509761 • Big Springs, Tooele Co., UT, 0.35 air km W of Hwy 73 and W Big Springs Street intersection; 40.26159° N, 112.09927° W; 29 Sep. 2022; K. Purington leg.; ANSP 509765 • Blue Spring Hills area, Blue Creek Spring; 41.83215° N, 112.458297° W; 20 Nov. 2022; C. Lundskog leg.; ANSP 509740 • Cold Spring ; 39.45514° N, 113.956962° W; 3 Aug. 2022; Kevin Wheeler and Luke Matscheck leg.; ANSP 509745 • Delle Spring , 40.55572° N, 112.73913° W; 8 Feb. 2022; K. Purington leg.; ANSP 509762 • Dove Creek Hills, 41.68214° N, 113.543057° W; 22 Sep. 2022; C. Lundskog leg.; ANSP 509739 • Ninemile Reservoir 1 (Spring along east side of Reservoir ), 0.3 air km N of Hwy 89 and Hwy 137 junction, 39.17333° N, 111.70344° W; 7 Nov. 2022; K. Purington leg.; ANSP 509753 • Ninemile Reservoir 2 (south end of reservoir on north side of Hwy 89); 39.16877° N, 111.71576° W; 7 Nov. 2022; K. Purington leg.; ANSP 509754 • North Beck , 39.30384° N, 114.008049° W; 2 Aug. 2022; Kevin Wheeler, Luke Matscheck legs.; ANSP 509743 • Pipe Spring, (near unnamed spring SE Lampo junction), 41.62948° N, 112.415231° W; 20 Nov. 2022; C. Lundskog leg.; ANSP 509741 • Red Barn WMA, 41.10818° N, 111.750344° W; 20 Nov. 2022; C. Lundskog leg.; ANSP 509742 • Sixmile Spring (near Mantai WMA), 0.09 air km SE of Hwy 89; 39.24485° N, 111.64901° W; 7 Nov. 2022; K. Purington leg.; USNM 509766 • Tintic Valley, McIntyre, 1.0 air km SW of McIntyre Rd and Union Pacific Rd Intersection ; 39.83149° N, 112.18005° W; 1 Nov. 2022; K. Purington leg. ANSP 509763 • unnamed spring near Sixmile Springs, 1.65 air km E of Simpson Springs Rd, ~ 500 m NW of Sixmile ; 39.91864° N, 112.76211° W; 3 Nov 2022; K. Purington leg.; ANSP 509767 • unnamed spring tributary to Middle Deep Creek at South Ibapah CSF monitoring site; 40.01749° N, 113.99415° W; 10 Mar. 2022; K. Purington leg.; ANSP 509764 • Murray Spring, Cache Valley ; 41.6208° N, 111.9419° W; 22 Sep. 2022; C. Lundskog leg.; ANSP 509737 • unnamed spring, northeast of Mushroom Springs, Antelope Island ; 40.9256° N, 112.1658° W; 22 Sep. 2022; C. Lundskog leg.; USNM 509738 • Gandy Marsh ; 39.48507° N, 113.91688° W; 2 Aug. 2022; Kevin Wheeler and Luke Matscheck legs.; ANSP 509744 • Foote Spring ( Bishop ); 39.41553, 113.870355 ° W; 2 Aug. 2022; Kevin Wheeler, Luke Matscheck leg.; ANSP 509746 • Cascade Springs, Provo River drainage; 40.45842° N, 111.54962° W; 21 Sep. 2022; K. Purington leg.; ANSP 509747 • unnamed spring, City Creek Canyon; 40.8255° N, 111.79621° W; 20 Sep. 2022; K. Purington leg.; ANSP 509748 • unnamed spring, north of Heber City, Provo River drainage, 0.25 air km SE of E 1200 N and Hwy 189 intersection, E side of Hwy 189; 40.51965° N, 111.4105° W; 10 Nov. 2022; K. Purington leg.; ANSP 509749 • unnamed spring, South Fork, Provo River drainage (near River ); 40.3474° N, 111.55202° W; 21 Sep. 2022; K. Purington leg.; ANSP 509750 • unnamed spring, South Fork, Provo River drainage, (near Spring ); 40.34701° N, 111.55191° W; 21 Sep. 2022; K. Purington leg.; ANSP 509751 • unnamed springs, source of Spring Creek, Utah Lake drainage; 40.38348° N, 111.82372° W; 20 Sep. 2022; K. Purington leg.; ANSP 509752 • Clover Creek, at Clover Springs Campground, 0.11 air km W of S Hwy 199; 40.34613° N, 112.55098° W; 24 Oct. 2022; K. Purington leg.; ANSP 509755 • Big Springs at Fountain Green Fish Hatchery ; 39.63629° N, 111.67309° W; 7 Nov. 2022; K. Purington leg.; ANSP 509756 • Indian Springs , 4.75 km E of Simpson Springs Rd; 39.98514° N, 112.73612° W; 3 Nov. 2022; K. Purington leg.; ANSP 509757 • Lee Creek, 1.75 air km SW of E Lee Creek Rd; 39.98786° N, 112.69083° W: 3 Nov. 2022; K. Purington leg.; ANSP 509758 • Thistle Creek, Peaceful Creek Ranch; 39.87572° N, 111.53957° W: 4 Oct. 2022; K. Purington leg.; ANSP 509759 • unnamed spring ~ 500 m E of Mud Spring , 2.4 air km WNW of Black Crook Peak; 39.98438° N, 112.57024° W; 1 Nov. 2022; K. Purington leg.; ANSP 509760 .

Redescription

Shell small to medium-sized, ovate to narrowly conical ( Fig. 10 ); height, 2.7–5 mm; width, 1.3– 2.2 mm, whorls, 4.25–5.25. Protoconch mostly smooth with weak wrinkles at apex or slight spiral lines. Teleoconch whorls convex, shoulders vary from weak to strong; body whorl often separated from the aperture in the largest shells. Aperture ovate, inner lip slightly thickened to thick, with or without columellar shelf, columellar lip slightly reflected, outer lip thin and slightly prosocline. Umbilicus rimate to shallowly perforate. Periostracum brown to light brown, or tan. Often periostracum is missing and spire is variously pitted and eroded.

Operculum amber to dark amber, ovate, eccentric nucleus sometimes reddish in color, transparent surface; dorsal surface frilled. Attachment scar margin sometimes thickened along inner edge or all around, callus weak. Central tooth 26–32 µm wide, with indented to highly indented dorsal edge, medium to largely; lateral cusps, 4–7; central cusp wide or narrow, long to short, longer than laterals; sometimes notched at the distal end, shovel to dagger-like; basal cusps small to medium-sized ( Figs 8–9 ). Basal tongue broadly V-shaped, basal sockets are medium depth. Lateral margins thickened, neck weak. Inner marginal teeth with 20–33 cusps; outer marginal teeth with 28–39 cusps.

Cephalic tentacles, snout, foot unpigmented, light brown, to brown-gray. Opercular lobe dark all around. Neck pigmented with dark granules. Pallial roof and visceral coil brown to black, sometimes extending to the entire animal. Penial filament unpigmented to lightly on proximal half to completely pigmented. Ctenidium of medium height and width, filaments 16–23, overlapping pericardium; osphradium narrow, small, positioned from posterior to central portion of the ctenidium.

Ovary with 0.5–1.0 whorl, overlapping posterior stomach chamber. Albumen gland extent into pallial cavity variable from none to long (0–25%). Capsule gland equal in length to the albumen gland or shorter and narrow; ovate to subglobose in section, with a weak to medium depth rectal furrow. Ventral channel overlaps the capsule gland, well-developed longitudinal fold. Genital aperture subterminal or terminal pore or slit, sometimes weakly raised with or without a short anterior extension. Coiled oviduct a posterior loop sometimes with a weak twist, small coil, or horizontal loop slightly behind pallial wall. Oviduct and bursa duct merge just behind wall of pallial cavity. Bursa copulatrix medium in length and width, ovate-elongate to subglobular, longitudinal with 33–80% of the length posterior to the gland, anterior portion slightly overlapped by gland. Bursa duct originating from anterior edge or slightly lateral to the midline, narrow to medium width and medium length, embedded shallowly in albumen gland, the same length as bursa copulatrix. Seminal receptacle pouch or sac-like, small to medium-sized, narrow, short, overlapping proximal bursal duct.

Testis 1.5–2 whorls, filling half to nearly all of digestive gland behind the stomach, overlapping both chambers of stomach to the edge of the style sac. Prostate gland small, bean-shaped, ovate in section, entirely visceral or with short section in pallial cavity; pallial portion of vas deferens undulating or with distinctive bend or loop at proximal end. Penis large ( Fig. 11 ); with an elongate-rectangular base, smooth; filament tapered and slightly to darkly pigmented, filament varies from short ( Fig. 11D ) and narrow to medium length and elongate ( Fig. 11A ); penial lobe short to medium and distally tapered or only slightly narrower than base. Penial glands vary in their presence and position. Terminal gland, if present, may be small to large, transverse, slightly curved, and largely borne on the ventral surface. Terminal gland sometimes split into two ( Fig. 11D ). Ventral gland (if present) small to large, narrow or circular-ovate, transverse, positioned near base of lobe on low swelling. In some individuals, additional glands at the base of the filament have been observed and on the dorsal surface of the penial lobe. Penial duct straight, near outer edge.

Distribution

Distribution confirmed here with DNA sequence data includes USA: Utah, Idaho, Wyoming, and Nevada. The Material examined (above and Appendix 1) lists the localities where P. pilsbryana has been confirmed present.

Taxonomic remarks

The source population of the holotype and paratypes described as P. pilsbryana is uncertain. This species was described from dry shells found in beach drift ( Baily & Baily 1952) as Amnicola pilsbryi from Lifton, ID. The description of the travels on which the types were collected includes “on the shores of Bear Lake, Lifton Idaho at the North End…” and two sites were listed as “Lifton; Ideal Beach”. In the description of their collecting trip ( Baily 1950), the author described collecting drift shells at these two beach sites in the north and south ends of the lake. The description of spring-dwelling snails from beach drift (dry shells) makes it impossible to precisely identify the spring that is the source of the shells found by Baily & Baily (1952). There are numerous springs in the area that drain into Bear Lake and there are several named species and unnamed lineages of Pyrgulopsis found near the lake. In our attempts to sample representatives of P. pilsbryana , we collected these specimens at Swan Springs and Jacobson Springs, both within 20 km of the type locality, resulting in collection of Colligyrus greggi (Pilsbry, 1935) and Pyrgulopsis Lineage D ( Liu et al. 2018), making selection of material to represent P. pilsbryana challenging but an adequate substitute must be used to consider the identity of this species.

The first description and figures of the internal anatomy of P. pilsbryana ( Hershler 1994) , used snails sampled from “an unnamed spring about 0.6 km NW of Lakota”. This spring is about 18 km from the type locality on the west side of the lake and based on the coordinates, was likely called “Little Spring Stream” (41.985174° N, 111.413132° W). Unfortunately, we did not find springsnails at this site and material could not be incorporated into this study. For the phylogenetic study that recommended synonymy of P. pilsbryana ( Liu et al. 2018) , the samples representing this species were collected from “Spring, Saint Charles Campground, Bear Lake Co., ID”, approximately 13 km from the type locality and on the north end of the lake. As this locality is the closest to the type locality and could result in shells being washed to the beach at Lifton, we took the snails from St Charles Campground as a better likely representative of P. pilsbryana . In addition, we examined this lot (USNM 858281) and some individuals from this lot strongly resemble the shell morphology of the holotype and paratypes of this species. Finally, in the morphometric analysis individuals from this population fall within the 95% ellipse with the type of P. pilsbryana . It remains possible that another spring in the vicinity hosts “true pilsbryana ” but we consider these samples to be the best representative of P. pilsbryana and the likely source of beach drift shells described by Baily & Baily (1952).

Pyrgulopsis nonaria and P. transversa were described ( Hershler 1998) and distinguished from P. pilsbryana largely on the basis of penial ornamentation, a feature that the same author ( Liu et al. 2018) later came to realize had greater variability across individuals and populations than initially understood. In Table 3, we summarize the lines of evidence we have assembled to determine if there is one or multiple distinct biological units in this group. We conclude from the majority of this evidence that there is one unit of diversity and by priority it should retain the name P. pilsbryana .

Figures

Fig. 8. Radula of individuals from: A. Unnamed spring about 0.6 km northwest of Lakota, Rich Co. UT, from redescription of Pyrgulopsis pilsbryana (Baily & Baily, 1952) USNM 858279 (Hershler 1994: fig. 29a). B. Ninemile Springs (P. nonaria Hershler, 1998 type locality). C. Sixmile Springs (P. transversa Hershler, 1998, type locality). Scale bars = 10 μm.

Fig. 9.Violin plot with box plot (quantiles) showing distribution of measurements of the length and width of the central radula cusp for populations from Ninemile Springs (six individuals, 195 teeth), Sixmile Springs (six individuals, 133 teeth), Vernon Reservoir (six individuals, 239 teeth), and Big Springs (seven individuals, 422 teeth). A Wilcoxon rank sum test found these populations were significantly different (p ≤ 0.001) in this measurement.

Fig. 10. Shells of Pyrgulopsis pilsbryana (Baily & Baily, 1952). A. OR363192, DNA 4383, Sixmile Springs. B. OR363185, OR365628, DNA 4374, Ninemile Spring. C. St Charles Campground. D. Dove Creek Hills. E. Vernon Reservoir. F. Red Barn WMA. G. North Beck. For complete locality details and USNM numbers see Appendix 1. Scale bars = 0.5 mm.

Fig. 11. Variation in penial morphology in Pyrgulopsis pilsbryana (Baily & Baily, 1952). A. Ventral aspect of individual resembling description of P. transversa Hershler, 1998, OR363193, OR365631, DNA 4385, Sixmile Spring.B. Ventral aspect of individual resembling description of P. nonaria Hershler, 1998 morphology, OR363185, OR365628, DNA 4374, Ninemile Spring. C–D. Same individual, ventral and dorsal view, OR363198, OR365616, DNA 4436, Blue Spring Hills. E–F. Same individual, ventral and dorsal view, OR365619, DNA 4433, Dove Creek Hills. G–H. Same individual, ventral and dorsal view, DNA 4414, Middle Deep Creek, morphology with features of both P. transversa and P. pilsbryana. Abbreviations: Dg = dorsal gland; Pf = penial filament; Pg = penial gland; Pl = penial lobe; Tg = terminal gland; Vg = ventral gland. Illustrations by Kevin Alanis.