Pyrgulopsis harrymilleri Perez, 2021

Perez, Kathryn E., Leal, Manuel Spor, Glover, Houston, Chastain, Rebecca T., Hutchins, Benjamin T. & Schwartz, Benjamin, 2021, Two new species of Pyrgulopsis Call & Pilsbry, 1886 (Mollusca: Caenogastropoda: Hydrobiidae) from springs in the Rio Grande watershed in Texas, Zootaxa 5071 (3), pp. 384-402 : 390-391

Pyrgulopsis harrymilleri Perez , sp. nov.

Figs. 5A–F , 6A–F , 7A–D .

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Diagnosis. A globose to low-conical snail with strong growth lines on teleoconch. Aperture ovate and usually slightly separated from body whorl. Mantle tissue pigmented gray-black. Sharply pointed median cusp of central radular teeth. Penial gland bifurcate at proximal end.

Types. Holotype ANSP A483285 , paratypes ANSP A483286 , all from Vasquez Springs , Presidio County, Texas.

Type locality. Vasquez Spring , N of Candelaria, 30.224070 W, - 104.583990 N, Presidio County, TX

Etymology. We use the specific epithet “ harrymilleri ” in honor of Dr. Harry Miller III and Harry Miller IV who provided support and access to land, which allowed discovery of this Pyrgulopsis species.

Remarks. We propose the common name “Millers’ springsnail” in honor of the Millers and aligning with common naming convention for honorific names in Pyrgulopsis .

Description. Shell globose to broadly low-conical, light tan in color, relatively short spire with convex to slightly shouldered whorls. Whorls with a distinct suture. Protoconch with periostracum mostly eroded in some individuals. The initial portion lightly wrinkled with a few small spiral lines. Teleoconch with strong growth lines. Aperture ovate, angled above, adnate, or usually slightly separated from the body whorl (in larger shells). Peristome complete, inner lip slightly thickened and slightly reflected in the columellar portion. Outer lip slightly prosocline, sinuate adapically. Umbilicus narrow to rimate. Average shell measurements for n= 10 adult individuals: shell height= 2.40 mm (SD=0.21), spire height= 0.46 mm (SD=0.08), body whorl height= 1.95 mm (SD=0.15), shell width= 1.78 mm (SD=0.09), body whorl width= 1.47 mm (SD=0.08), aperture height= 1.24 mm (SD=0.07), aperture width= 1.03 mm (SD=0.06), number of whorls, 4.05 (SD=0.23).

Operculum( Fig.6E,F )narrowly ovate,flat,light amber;eccentric nucleus,paucispiral growth pattern.Attachment scar slightly thickened midway between nucleus and columellar edge. Attachment region callus moderately thick. Growth lines distinct, simple. Outer margin thin (nearly colorless), but with raised ridge, particularly along outer margin but with narrow thicker edge along inner margin.

Central radular tooth ( Fig. 7 ) with moderately indented dorsal edge; lateral cusps 5–8; central cusp sharply pointed, considerably broader and longer than laterals, basal cusp 1, narrowly elongate, with strong dorsal support. Basal process medium width, broadly v-shaped; basal sockets deep. Lateral tooth face tall with broad neck and outer wing; central cusp shovel-like, sometimes flexed, lateral cusps 1–3 (inner) and 1–4 (outer); outer wing broad and about 200% length of cutting edge; basal tongue well developed. Inner marginal teeth having 20–25 cusps; fifth cusp from outer edge enlarged, sometimes buttressed with wide base including adjacent teeth. Outer marginal teeth having 31–34 cusps, inner edge sometimes having a short wing, near mid-length.

Tentacles pale with darkly pigmented patch at base and one solid black line running the entire length of the tentacle. Snout dark gray-black, light colored on distal edge. Foot darkly pigmented on anterior surface, and light colored beneath. Opercular lobe black along anterior edge and with sides, pale in the center. Neck pigmented along edges, pale in center. Visceral coil and pallial roof both darkly pigmented, almost black.

Ctenidium occupies a portion of the pallial cavity, filaments much broader than high, with filaments elongate, roughly triangular, wider at the base, lateral surface with elongate ridge, ~15–20. Middle and posterior filaments with widely elongated base. Osphradium elongate, short, opposite posterior end to middle of ctenidium, anterior end simple.

Penis large ( Fig. 5D,E ); filament medium length, narrow; lobe slightly shorter than filament, very broad. Penial gland covers half the length of the filament, distal to the body, with a strong bifurcation proximally. Dorsal gland (Dg) 1 short, broad, situated at proximal end of filament; Dg2 slightly curved, situated on a swelling left of Dg1; Dg3 similar in size, positioned near inner edge of lobe. Terminal gland elongate, curved, and situated entirely on ventral side of lobe. Ventral gland weakly curved and prominent, on large subterminal swelling. Filament with moderately dark internal pigment.

Capsule and albumen gland similar in size. Pallial portion of the albumen gland is large. Genital aperture near terminal end of capsule gland. Coiled oviduct a large loop, partially imbedded in albumen gland, with a light scattering of pigment. Bursa copulatrix rounded. Seminal receptacle elongate to pyriform, narrows near insertion with common duct of seminal receptacle and coiled oviduct. In many individuals, a line of oval fecal pellets fills intestine, passing along lateral edge of ctenidium. No fecal pellets observed in P. rubra sp. nov. or P. metcalfi individuals.

Habitat and Distribution. This species’ known range is in Vasquez Spring on the western slopes of the centralsouthern portion of the Sierra Vieja mountains (~ 7 km SW of Capote Peak). The habitat is approximately the upper 10 m of a 20 m length of narrow, high-gradient spring run, 10 to 30 cm wide and 0.5 to 3 cm deep on the upstream. The snails occupy ~50% of a tiny spring run that discharges from below a boulder on a steep hillslope at a geologic contact between volcanic talus and an underlying lens of weathered volcanic ash. Substrate consisted of gravel and small rocks, with sand and fine organics, surrounded by spike rushes. Habitat is partly fenced but fence is broken, and stream is visibly impacted by animals; likely audad ( Fig. 11A ). At the source, water temperature was 26.81 °C, pH = 7.73, conductivity = 1297 (µS/cm), dissolved oxygen = 10.87 mg /L. Two adjacent seeps did not have snails.

Figures

FIGURE 5. Shells and anatomical features of Pyrgulopsis harrymilleri sp. nov.A–C.holotype,Vasquez Spring,ANSPA483285, height=2.2 mm, width=1.74 mm. D–E. Penial anatomy illustrating glandular features. Pf=Penial filament, Tg=terminal gland, Tl=terminal lobe, Vg=ventral gland, Dp=penial gland, Dg1=dorsal gland 1, Dg2=dorsal gland 2, Dg3=dorsal gland 3. D. Penis, dorsal surface. E. Penis, ventral surface. F. Animal with shell mostly removed to show dark gray-black pigmentation.

FIGURE 6. Scanning electron micrographs of shells (A–B), protoconch (C–D), and opercula (E = outer side; F = inner side) of Pyrgulopsis harrymilleri sp. nov. Scale bars A–B = 500 µm; C = 100 µm; D = 20 µm; E–F = 200 µm.

FIGURE 7. Scanning electron micrographs of radula of Pyrgulopsis harrymilleri sp. nov. A = portion of radular ribbon; B = central radular teeth; C = lateral and inner marginal teeth; D = outer marginal teeth. Scale bars = 10 µm.

FIGURE 11. Type localities for new species. A. P. harrymilleri sp. nov., Vasquez Spring, Presidio Co., TX. Photo by B. Schwartz. B. P. rubra sp. nov., Palo Amarillo Springs, Presidio Co., TX. Photo by K. Perez.