Fluminicola fremonti, Hershler & Liu & Frest & Johannes, 2007

Hershler, Robert, Liu, Hsiu-Ping, Frest, Terrence J. & Johannes, Edward J., 2007, Extensive diversification of pebblesnails (Lithoglyphidae: Fluminicola) in the upper Sacramento River basin, northwestern USA, Zoological Journal of the Linnean Society 149 (3), pp. 371-422 : 386

FLUMINICOLA FREMONTI SP. NOV. (FREMONT

PEBBLESNAIL)

Type material: Holotype ( Fig. 8A ), USNM 1020660 , Hunters Spring on the north side of FS28, Fremont National Forest , Lake County, Oregon (704840 E, 4684990 N, 1604 m), 26 August 2000 TF, EJ . Paratypes, USNM 1020661 , from same lot as holotype .

Referred material: USNM 1020662 , topotypes, 30 October 2002 , TF, EJ.

Diagnosis: Differs from closely similar F. turbiniformis in its smaller basal cusps on the central radular teeth, the typically pointed distal end of the penis, the presence of internal pigment in the penis, a more triangular-shaped bursa copulatrix, a longer bursa copulatrix duct, a larger seminal receptacle, and the absence of a seminal receptacle duct. Readily distinguished from geographically proximal F. modoci by its typically broader shell, narrower columellar lip, and lighter coloured periostracum.

Description: Shell ( Fig. 8A–E ; Table 3) usually subglobose, rarely ovate-conic, rarely having eroded spire; height, 2.32–3.98 mm; whorls, 3.25–4.0. Protoconch 1.3–1.4 whorls, diameter approximately 0.70 mm. Teleoconch whorls medium convex, narrowly shouldered. Aperture broad, angled above. Parietal lip complete, usually adnate, thin and curved across body whorl; occasionally slightly disjunct, thickened. Columellar lip narrow to medium width, often overlapping part of umbilical region. Outer lip usually thin, prosocline. Shell anomphalous or having narrow umbilicus, umbilical region narrowly excavated. Periostracum tan or light brown. Outer surface of operculum smooth ( Fig. 8F ). Central radular tooth approximately 37 µm wide, cutting edge convex, lateral cusps four to five; central cusp near parallel-sided, distal end rounded; basal cusps one; basal tongue broadly V- or U-shaped, equal to lateral margin ( Fig. 8H ). Lateral tooth face broadly rectangular; central cusp rounded; lateral cusps three (inner), four to five (outer); outer wing flexed, medium length ( Fig. 8I ). Inner marginal teeth ( Fig. 8G ) having 27–33 cusps. Outer marginal teeth having 28–36 cusps; basal wing rectangular ( Fig. 8G, J ). Head-foot dark brown, almost black. Ctenidium connected to pericardium by short, efferent branchial vessel (fide Hershler & Ponder, 1998: fig. 18c); ctenidial filaments approximately 16, weakly pleated. Osphradium elongate, positioned opposite middle of ctenidium. Female reproductive anatomy shown in Figure 6A . Bursa copulatrix longitudinal, triangular, duct medium length. Seminal receptacle mediumsized, partly overlapped by albumen gland. Albumen gland having moderate rectal furrow. Capsule gland a little longer than albumen gland. Genital aperture a simple pore. Penis medium-sized, coiled, distal end usually pointed, rarely tapering or having papilla ( Fig. 7A ). Penis surface pale; internal black granules scattered along length of penial duct. Penial duct near centrally positioned, weakly undulating medially.

Distribution: Known only from the type locality, which is located in the Thomas Creek drainage, Goose Lake basin ( Fig. 9 ).

Etymology: Named after John C. Frémont, intrepid early explorer of the American West. The single locality for this species is located in the Fremont National Forest.

Remarks: On the basis of sequence divergence data, F. fremonti is most similar to species living in the lower Pit River basin: F. anserinus (described below) ( COI 3.5–3.8%) and F. scopulinus (described below) (cytb 5.5–5.8%).

Figures

Figure 6. Female glandular oviduct and associated structures (viewed from the left side) for six species of Fluminicola. A, F. fremonti (USNM 1020661). B, F. warnerensis (USNM 1020653). C, F. erosus (USNM 1020664). D, F. favillaceus (USNM 1020670). E, F. neritoides (USNM 1020682). F, F. anserinus (USNM 1020728). Scales = 0.5 mm. Ag, albumen gland; Bu, bursa copulatrix; Cg, capsule gland; Dbu, bursal duct; Ga, genital aperture; Pc, posterior wall of pallial cavity; Rf, rectal furrow; Sr, seminal receptacle; Vc, ventral channel of capsule gland.

Figure 7. Penes (upper side) of the 13 Fluminicola species newly described herein. A, F. fremonti (USNM 1020661). B, F. warnerensis (USNM 1020653). C, F. lunsfordensis (USNM 1020689). D, F. erosus (USNM 1020664). E, F. favillaceus (USNM 1020670). F, F. caballensis (USNM 1020676). G, F. neritoides (USNM 883563). H, F. ahjumawi (USNM 1020699). I, F. umbilicatus (USNM 1020706). J, F. anserinus (USNM 1020728). K, F. potemicus (USNM 1020719). L, F. scopulinus (USNM 1020722). M, F. multifarius (USNM 883782). Scale = 0.25 mm. Pd, penial duct.

Figure 8. Shells, opercula, and radula of Fluminicola fremonti. A, holotype (USNM 1020660). B–E, USNM 1020661. Scales = 1 mm. F, outer side of operculum (USNM 1020661). Scale = 100 µm. G, portion of radular ribbon (USNM 1020661). Scale = 20 µm. H, central radular teeth (USNM 1020661). Scale = 10 µm. I, lateral radular tooth (USNM 1020661). Scale = 10 µm. J, outer marginal tooth, with basal, rectangular wing (Bw) on outer edge. Scale = 10 µm.

Figure 9. Map showing the distribution of eight species (plus Fluminicola sp.) in the Goose Lake and Pit River basins. Some symbols represent multiple, closely proximal localities.