Pyrgulopsis owyheensis, Hershler, Robert & Liu, Hsiu-Ping, 2009

Hershler, Robert & Liu, Hsiu-Ping, 2009, New species and records of Pyrgulopsis (Gastropoda: Hydrobiidae) from the Snake River basin, southeastern Oregon: further delineation of a highly imperiled fauna, Zootaxa 2006, pp. 1-22 : 13-19

Pyrgulopsis owyheensis sp. nov.

( Figs 6–9 )

Types. Holotype ( Fig. 6 A), USNM 883435, Owyhee Spring, T. 32 S, R. 42 E, SE 1/4 sec. 6, Gary L. Vinyard, 27/vii/1993. Paratypes, USNM 1116915 (from same lot, 2283 specimens).

Etymology. A geographic epithet referring to the distribution of this species in the Owyhee Uplands region.

Referred material. OREGON. Malheur County. USNM 883448, Cherry Spring, T. 36 S, R. 43 E, sec. 14, 29/vii/1993. USNM 883437, Tree Spring, T. 35 S, R. 41 E, sec. 36, 29/vii/1993. USNM 1092853, 1092854, ibid., 447555 E, 4700938 E, 16/vii/2006, 18/vii/2006. USNM 1106163, USNM 1102150, ibid., 447559 E, 4700915 E, 11/v/2007, 13/v/2007. USNM 1115387, spring tributary to Owyhee River upflow from Tudor Warm Springs, 484401 E, 4707220 N, 11/x/2006. USNM 1070694, USNM 1071458, USNM 1115399, Tudor Warm Springs, east side of river, second spring from north, 485060 E, 4708420 N, 25/ix/2002. USNM 1115389, USNM 1115400, ibid., 484936 E, 4708680 N, 11/v/2007, 12/v/2007. USNM 1115390, Tudor Warm Springs, east side of river, third spring from north, 484935 E, 4708661 N, 12/v/2007. USNM 1115401, Tudor Warm Springs, west side of river, second spring north of mouth of Warm Springs Canyon, 484853 E, 4708749 N, 19/vii/2006. USNM 1071259, springs on south side of Owyhee River, 0.32 km west of Sand Hollow, 455620 E, 4736750 N, 24/ix/2002. USNM 883450, spring 1.6 km east-southeast of Owyhee Spring, T. 32 S, R. 42 E, sec. 6, 27/vii/1993. JFBM 20915, Owyhee Spring, T. 32 S, R. 42 E, sec. 6, 18/v/1982. USNM 1070697, USNM 1071456, ibid., 450500 E, 473600 N, 26/ix/2002. USNM 1092819, Owyhee Spring, first spring south of main spring, 450415 E, 4737821 N, 16/vii/2006. USNM 1102149, USNM 1102162, ibid., 450422 E, 4737819 N, 11/v/2007, 13/v/2007. USNM 1107068, seep wall on west side of Owyhee River, just above mouth of Crooked Creek, 443352 E, 4747342 N, 5/ix/2007. USNM 1107070, spring on east side of Owyhee River below mouth of Crooked Creek, 443026 E, 4749973 N, 5/ix/2007. USNM 1115388, spring on east side of Owyhee River, above Long Sweetwater rapids, 442355 E, 4753770 N, 6/ix/2007. USNM 1107073, Weeping Wall springs, west side of Owyhee River, just below mouth of Granite Creek, 440473 E, 4760771 N, 6/ix/2007. USNM 1107074, spring on east side of Owyhee River, above Artillery rapids, 443011 E, 4765226 N, 7/ix/2007. USNM 1102152, Kane Springs, 462846 E, 4846953 N, 15/v/2007.

Diagnosis. A small to medium-sized species having an ovate to narrow conic shell with medium to highly convex whorls. Penis having a medium-sized lobe and medium length filament; penial ornament consisting of a transverse terminal gland; a penial gland; and a well-developed, distally positioned ventral gland.

Description. Shell ( Fig. 6 A–I) ovate to narrow conic, height about 1.6–3.3 mm; whorls, 3.50–4.75. Periostracum tan or dark brown, thin. Protoconch ( Fig. 6 J–K) near planispiral, about 1.5 whorls, diameter about 350 µm, surface entirely smooth or weakly wrinkled on initial 0.75 whorl. Teleoconch whorls medium or highly convex, narrowly and sometimes distinctively shouldered ( Fig. 6 A), last 0.5–0.25 whorl sometimes slightly loosened ( Fig. 6 E); sculpture of collabral growth lines. Aperture ovate, angled adapically. Inner lip usually disjunct, rarely adnate, usually thickened internally; columellar shelf absent; outer lip thin, weakly prosocline or orthocline. Umbilicus narrow or perforate; umbilical area sometimes having a narrow, adapertural groove.

Shell measurements (mean ± standard deviation in parentheses): height 2.13–2.78 mm (2.53+0.16), width 1.79–2.19 mm (2.00+0.11), body whorl height 1.87–2.39 mm (2.13+0.12), body whorl width 1.43–1.89 mm (1.69+0.10), aperture height 1.19–1.41 mm (1.29+0.06), aperture width 1.05–1.32 mm (1.17+0.07), shell width/height 0.69–0.91 (0.79+0.05), body whorl height/shell height 0.78–0.88 (0.84+0.02), aperture height/ shell height 0.46–0.56 (0.51+0.03) (USNM 1116915, n = 30).

Measurements of holotype: height 2.29 mm, width 1.99 mm, body whorl height 1.97 mm, body whorl width 1.45 mm, aperture height 1.34 mm, aperture width 1.19 mm, shell width/height 0.87, body whorl height/shell height 0.86, aperture height/shell height 0.58, 3.75 whorls.

Operculum thin, flat, amber-colored, multispiral with eccentric nucleus; last half whorl usually frilled on outer side ( Fig. 7 A–B); inner side sometimes having a distinct rim along outer edge ( Fig. 7 C), attachment scar border slightly thickened along inner edge to strongly thickened almost all around ( Fig. 7 C–F). Radula taenioglossate ( Fig. 8 A), with about 50 well-formed rows of teeth. Central teeth ( Fig. 8 B) about 27 µm wide; cutting edge concave, sometimes strongly so; lateral cusps 4–6; central cusp narrow, considerably longer than lateral cusps, pointed, parallel-sided proximally; basal cusp 1, small; basal tongue V-shaped, length about equal to lateral margins. Lateral tooth ( Fig. 8 C) face rectangular, angled; central cusp large, hoe-shaped; lateral cusps 2–3 (inner), 2–4 (outer); outer wing rather broad, straight, about 160% length of cutting edge; basal tongue well developed. Inner marginal teeth ( Fig. 8 D) having 17–22 cusps. Outer marginal teeth ( Fig. 8 E) having 23–36 small cusps; a rectangular wing along inner edge was seen in some specimens ( Fig. 8 F).

Head-foot generally dark brown. Cephalic tentacles pale dorsally except for central pigmented strips, ventral surfaces pale. Distal lips of snout light brown or pale. Sole of foot pale or grey. Pallial roof, visceral dark brown. Ctenidium well developed, positioned a little in front of pericardium; ctenidial filaments about 15. Oshpradium narrow, positioned posterior to middle of ctenidium. Prostate gland small, pea-shaped, with about 33% of length in pallial roof. Anterior vas deferens opening from ventral edge of prostate gland a little in front of pallial wall, section of duct on columellar muscle having weak bend. Penis ( Fig. 9 A–D) medium to large, base elongate-rectangular, inner edge smooth; penial filament medium length, tapering, oblique; lobe medium-sized, rectangular or tapering, oblique. Terminal gland narrow, transverse, overlapping dorsal and ventral edges of lobe. Penial gland overlapping up to 50% of filament length, slightly overlapping penis posteriorly. Ventral gland well developed, narrow, distally positioned, borne on short stalk ( Figs 9 B, D). Penial duct narrow, straight. Penial filament containing a dense core of black pigment; penis otherwise pigmented with scattered black granules. Female glandular oviduct and associated structures shown in Figure 9 E–G. Coiled oviduct a large, posteriorly oblique, proximally kinked loop. Bursa copulatrix small, narrowly ovate, horizontal, largely overlapped by albumen gland. Bursal duct about as long as and slightly narrower than bursa, opening from distal edge, sometimes pigmented with black granules near edges. Seminal receptacle small, pouch-shaped, positioned near antero-ventral edge of bursa; duct short. Albumen gland about as long as capsule gland, entirely visceral or with very short pallial section, sometimes pigmented with scattered black granules. Capsule gland composed of a single tissue section. Genital aperture a sub-terminal slit.

Distribution and habitat. Pyrgulopsis owyheensis is disjunctly distributed among five small areas in southeastern Oregon (Owyhee River near Three Forks, Rattlesnake Creek drainage, Owyhee Spring area, lower Owyhee River, Malheur River drainage) ( Fig. 1 ). Additional sampling will be needed to determine whether the intervening areas are also inhabited by this species. Pyrgulopsis owyheensis lives in spring sources and stream outflows, some of which are thermal, and is found on a variety of hard substrates. This species was collected together with P. intermedia in a spring along the Owyhee River above Long Sweetwater rapids, and with the invasive New Zealand mudsnail, Potamopyrgus antipodarum (Gray) (USNM 1107078) at a seep wall above the mouth of Crooked Creek.

Remarks. Pyrgulopsis owyheensis differs from closely similar P. intermedia in size (shell height about half of that of the latter when in sympatry; Figs 6 F, 10A) and in its typically disjunct inner shell lip, longer and narrower penial filament, more distally positioned ventral gland of penis, and mitochondrial DNA sequences (6.9+0.01%, Table 2). None of our phylogenetic analyses supported a close relationship between these species (e.g., Fig. 2 ).

Shell variation within P. owyheensis ( Fig. 6 A–I) was minor, involving slight differences in size and shape ( Fig. 6 ). The sequence divergence between specimens from the type locality (Owyhee Spring) and the other four areas inhabited by this species ranged from 1.5–1.8% whereas the latter differed from each other by only 0.3–0.8%. This suggests the possibility of incipient speciation in the Owyhee Spring area and a need to manage these populations as a distinct conservation unit.

Radular count data were from USNM 1092854, USNM 1102152, USNM 1116915.

Figures

FIGURE 1. Map showing the distributions of Pyrgulopsis species in southeastern Oregon. Arrows indicate previously documented localities; all others are newly reported herein. Some of the symbols refer to multiple, closely proximal localities.

FIGURE 2. Maximum parsimony (MP) tree based on the COI dataset (TL = 322, CI = 0.64). Bootstrap support for nodes is provided when> 70 %. Bold-faced sequences are newly reported herein. Scale bar = one substitutional change per 100 nucleotide positions.

FIGURE 6. P. owyheensis sp. nov. A – I. Shells. Scale bar = 1.0 mm. A. Holotype, USNM 883435. B, USNM 1071259. C. USNM 1092854. D. USNM 1115390. E. USNM 1115400. F. USNM 1115388. G. USNM 1107074. H. USNM 1107073. I. USNM 1102152. J. Shell apex, USNM 1102152. Scale bar = 100 µm. K. Close-up of protoconch sculpture, USNM 1102152. Scale bar = 100 µm.

FIGURE 7. P. owyheensis sp. nov. A – F. Opercula. Scale bar = 500 µm. A – B. Outer side, showing frilled whorls, USNM 1116915, USNM 1092854. C – F. Inner side, showing variation in thickening of attachment scar margin, USNM 1116915, USNM 1102152, USNM 1092854, USNM 1092854. Rm = rim.

FIGURE 8. P. owyheensis sp. nov. A. Portion of radula ribbon, USNM 1116915. Scale bar = 20 µm. B. Central radular teeth, USNM 1116915. Scale bar = 10 µm. C. Lateral and inner marginal teeth, USNM 1116915. Scale bar = 10 µm. D. Inner marginal tooth, USNM 1116915. Scale bar = 10 µm. E. Outer marginal teeth, USNM 1116915. Scale bar = 10 µm. F. Outer marginal tooth, showing outer wing, USNM 1092854. Scale bar = 10 µm. Wg = wing.

FIGURE 9. P. owyheensis sp. nov.. A – B. Penis, USNM 1092819. Scale bar = 0.25 mm. A. Dorsal surface. B. Ventral surface. C – D. Penis, USNM 1102152. Scale bar = 0.5 mm. C. Dorsal surface. D. Ventral surface. E. Female glandular oviduct and associated structures (viewed from the left side), USNM 1092819. Scale bar = 0.25 mm. F. Bursa copulatrix and its duct. Scale as in “ E. ” G. Seminal receptacle and its duct. Scale as in “ E. ” Ag = albumen gland, Bu = bursa copulatrix, Cd = common duct of seminal receptacle and coiled oviduct, Cg = capsule gland, Co = coiled oviduct, Dbu = bursal duct, Ga = genital aperture, Pd = penial duct, Pf = penial filament, Pg = penial gland, Pl = penial lobe, Pw = posterior wall of pallial cavity, Sr = seminal receptacle, Tg = terminal gland, Vc = ventral channel, Vg = ventral gland.