Fluminicola potemicus Hershler & Liu & Frest & Johannes 2007, SP. NOV.

Type material: Holotype (Fig. 22A), USNM 1020718, unnamed spring pool on the west side of FS27 (Fend- ers Ferry Road), c. 10.8 rd km north of CA 299 junction, 4.18 km north of FS27 bridge over Potem Creek, west side of Potem Creek, inholding in Shasta National Forest, Shasta County, California (580660 E, 4524820 N, 439 m), 18 October 1992 TF, EJ. Paratypes (from same lot), USNM 1020719.

Referred material: USNM 1020720, topotypes, 28 September 2001 TF, EJ.

Diagnosis: Differentiated from similar species also living in the lower Pit River basin (e.g. F. anserinus) above. Differs from F. scopulinus (described below), from the Sacramento River headwaters, in its narrower shell (mean SH/ SW, 1.182, 1.136, respectively, P = 0.008), smaller shell umbilicus, and more posteriorly positioned ctenidium.

Description: Shell (Fig. 22A–G; Table 13) broadly or ovate-conic, rarely having eroded spire; height, 2.55– 3.31 mm; whorls, 3.0–3.75. Protoconch approximately 1.4 whorls, diameter approximately 0.51 mm. Teleoconch whorls medium convex, shoulders well developed. Aperture ovate, angled above. Parietal lip complete, narrowly adnate. Columellar lip narrow. Outer lip thin, orthocline or weakly prosocline. Shell perforate, umbilical region not excavated. Periostracum tan or light green. Outer surface of operculum smooth (Fig. 22H). Central radular tooth approximately 35 µm wide, cutting edge convex, lateral cusps three to four; central cusp parallel sided, rounded or weakly pointed; basal cusps one (two seen in one specimen); basal tongue U-shaped, even with lateral margin (Fig. 22J). Lateral tooth face broadly rectangular; central cusp rounded, lateral cusps two to three (inner), three to four (outer); outer wing weakly flexed, medium length (Fig. 22K). Inner marginal teeth having 22–28 cusps (Fig. 22I). Outer marginal teeth having 21–36 cusps; basal wing absent (Fig. 22I). Head-foot near pale, brown or grey. Ctenidium abutting pericardium; ctenidial filaments 14, without pleats. Osphradium elongate, positioned opposite middle of ctenidium. Bursa copulatrix horizontal, ovate or triangular, duct medium length. Seminal receptacle medium-sized, overlapped by albumen gland. Capsule gland a little longer than albumen gland. Genital aperture a simple pore. Penis medium-sized, usually tightly coiled, distal end tapering or pointed (Fig. 7K). Penis having medial patch of dark, internal pigment. Penial duct positioned near outer edge, nearly straight.

Distribution: Restricted to the type locality, which is situated in the lower Pit River basin, a short distance above Shasta Lake (Fig. 20).

Etymology: The specific epithet is based on the name of the type locality, which may have been derived from a Native American word meaning ‘mountain lion’ (Gudde, 1998).

Remarks: Fluminicola potemicus differs from other species of clade C described herein by 3.2–5.0% (COI) and 5.5–8.0% (cytb).

This species was referred to as Fluminicola n. sp. 2 by Frest & Johannes (1993).

FLUMINICOLA SCOPULINUS SP. NOV. (CASTLE CREEK