A systematic revision of the genus Juga from fresh waters of the Pacific Northwest, USA (Cerithioidea, Semisulcospiridae)

Juga is a genus of freshwater snails distributed from northern Washington to central California. The taxonomy and classification of the genus has a long and complex history, driven mainly by the features of their highly variable shells. The number of recognized species has fluctuated from ~9 to 11; however, it has been claimed that the actual diversity may be three times that number. We here present a systematic revision using a recently published molecular phylogeny as a framework, which supported the interpretation that there are only nine valid species. Comprehensive review of type material and original descriptions for all available species-group names indicates that almost all species previously considered valid were paraor polyphyletic grades of organization in shell morphology. Most species previously suggested to be putatively new were confirmed to be morphological variants of species already described. Species accounts include complete synonymies and partial chresonymies; the shells and radulae are illustrated and described. Lectotypes are designated for Melania plicifera Lea, 1838, M. silicula Gould, 1847, and M. rudens Reeve, 1860. Three species, Juga caerulea sp. nov., J. canella sp. nov., and J. douglasi sp. nov., are described as new and one species is excluded from the genus. The subgenera Calibasis D.W. Taylor, 1966 and Idabasis D.W. Taylor, 1966 are synonymized with Juga.


Introduction
Juga H. & A. Adams, 1854 is a genus of large-bodied, freshwater snails from the Pacific Northwest of the United States. Adults are ~1.5-3.5 cm in shell length and are conspicuous members of their benthic macroinvertebrate communities. They prefer cold, oligotrophic, well oxygenated waters of perennial seeps and springs, spring runs, creeks, and rivers with stable bottoms, but some are tolerant of low energy conditions in lakes (Fig. 1). They can reach densities of 1500 individuals/m 2 and are found on a wide variety of substrates from mud to sand, deciduous leaf litter, stones, submerged wood, and the spray-moistened sides of boulders (Fig. 2) where they graze on periphyton and detritus. The sexes are separate, and females are oviparous, depositing thick, finger-like, gelatinous egg mass (Fig. 2B) containing hundreds of irregularly arranged eggs on the undersides of hard surfaces including stones and sunken logs. Hatchlings do not leave the egg mass immediately, often not before adding at least an additional two whorls to the shell. They reach sexual maturity after three years with life spans on the order of five to seven and possibly as many as nine years (Diamond 1982;Hawkins & Furnish 1987;Furnish 1990;Frest & Johannes 1995a, 2010Furnish et al. 1997).
The name Juga also has been applied to semisulcospirids from the Russian Far East and adjacent regions of China and Korea (e.g., Zatravkin 1986;Bogatov & Zatravkin 1990;Prozorova 1990;Prozorova & Rasshepkina 2002, 2003. These were allocated to 'Parajuga' Prozorova & Starobogatov, 2004(Starobogatov et al. 2004, which is not a nomenclaturally available name (see ). Although its circumscription was unclear, the family-group name Jugidae Starobogatov, Prozorova, Bogatov & Sayenko, 2004 was also established apparently for Russian Far East species but is similarly nomenclaturally unavailable and considered a synonym of Semisulcospiridae J.P.E. Morrison, 1952(Bouchet et al. 2017. Rasshepkina (2007) used this name at the rank of subfamily to unite 'Parajuga' and Juga. Vinarski & Kantor (2016) followed Rasshepkina (2009) in returning the Russian species to Juga. However, molecular analyses have shown that at least one of these species, Melania amurensis Gerstfeldt, 1859, is more closely related to Asian species than to North American Juga Köhler 2016Köhler , 2017. Köhler (2016) transferred this species to Koreoleptoxis Burch & Jung, 1988 and later (Köhler 2017) hypothesized that other East Asian semisulcospirids would also fall here. Since then, Du et al. (2019aDu et al. ( , 2019b have significantly expanded our understanding of relationships among semisulcospirids from China, but nominal taxa from the Russian Far East have yet to be comprehensively revised and remain in taxonomic limbo. We agree with Köhler (2017) that their affinities likely lie among Asian species and do not consider them further here.
The American species of Juga are distributed from northern Washington to central California, primarily in Pacific drainages to the west of the Cascades at low to medium elevations. The northern end of their distribution is roughly coincident with the southern limit of the Cordilleran ice sheet [Late Wisconsin (Fraser) glaciation] on the Olympic Peninsula and the southeastern edge of Puget Sound in Washington State and extends to southern Sonoma County in central California. In Oregon and Washington, verified records show they extend east along the Columbia River past the mouth of the John Day River. East of the Cascades in Oregon Juga is mostly absent, apart from the Deschutes and upper Klamath watersheds and the John Day headwaters in the northeastern part of the state. In California, they extend into the upper reaches of the Pit River drainage in the northeastern part of the state and south along the western flank of the Sierra Nevada primarily in the Sacramento River drainage, including the Feather, Yuba, and American Rivers, as well as the northern Mokelumne River drainage (Cosumnes River). They also occur sporadically in interior drainages of the northern Great Basin in northeastern California, south-central Oregon, and northwestern Nevada. Reports of occurrences in British Columbia, Idaho, Colorado, Utah, Montana, and Wyoming (e.g., Bland & Cooper 1861;Tryon 1865;Ingersoll 1875Ingersoll , 1876Dall 1910;Henderson 1924Henderson , 1929Johnson et al. 2013) are erroneous (see e.g., Henderson 1936a;Johannes 2000b, 2010, andreferences therein;Campbell et al. 2016).
show that the genus was well established in what is now Washington State by the Late Eocene. At its peak during the Miocene and Pliocene, Juga extended beyond its present range into eastern Washington, Idaho, the Nevada Great Basin, to southern Central California . The most recent common ancestor of Juga is hypothesized to have ranged across the Beringean land bridge during warmer episodes of the Cenozoic and may have arrived in North America during the Paleocene-Eocene Thermal Maximum .  Lea, 1838)). B. Under submerged stones (with gelatinous egg masses). Youngs River Falls, just upstream of Youngs River Rd, Oregon (J. plicifera). C. On mud and leaves. Muddy Hollow, Oregon (J. bulbosa (A. Gould, 1847)). D. On submerged wood. Unnamed Creek at Skookum Creek Rd, Oregon (J. canella sp. nov.). E. On sand. Hat Creek, California (J. douglasi sp. nov.). F. On the spray-moistened sides of boulders. Pit River at U.S. Hwy 299, California (J. occata (Hinds, 1844)). diagnoses and subgeneric distinctions were confirmed to be variable within species, sometimes at a single site (Strong & Whelan 2019).
In anticipation of the molecular analyses that were eventually published in Campbell et al. (2016),  prepared a review of the nominal taxa allocated to Juga and of their type localities, type material, and taxonomic status. This review appeared in volume 43/44 of Malacological Review (Museum of Zoology, University of Michigan) for 2010-2011; however, we have not been able to establish the actual date of publication. The existing physical and digital archives at the University of Michigan cannot refine the date of printing or distribution (T. Duda pers. com.). The volume has not been widely distributed and was not stamped upon receipt at the University of Michigan library. Volume 41/42 for 2008-2009 was stamped as "Dec 2011" (T. Duda pers. com.), but as far as we can determine, volume 43/44 may have appeared as late as 2018. There are no nomenclatural acts in this work and for simplicity we refer to it as  In their review , nomina considered taxonomically valid were accompanied by descriptions of shell morphology and distribution, and occasional elaborations on the ecology and conservation status. Of the available species-group names for Recent Juga, they recognized 22 as taxonomically valid or potentially so, three as synonyms, and four as unrecognizable and/or not relocated. They also provided a list of names that they considered "invalid" or incorrectly used in combination with the genus-group name Juga and recognized 20 fossil species ranging in age from Eocene to Pliocene. While much valuable information was provided, the type material was not illustrated and the material examined was not listed or figured. The taxonomical framework was consistent with their previous works in considering that most nominal species represent distinct, valid species and that many records and historical museum lots, "do not fit readily into any named category" : 3). The information relevant for the nine species subsequently confirmed as valid in the molecular analyses of Strong & Whelan (2019) is highly fragmented and disorganized.
Thus, using the molecular phylogeny of Strong & Whelan (2019) as a framework, we here present a systematic revision of American species of the genus Juga. Species accounts include complete synonymies and partial chresonymies; the shells (including relevant type material) and radulae are illustrated and described. Distribution maps feature sequenced specimens, historical museum records, and type localities when well constrained. Three species are described as new.

Description
Shell. Thick, large, reaching ~3.5 cm in length; turriform, narrowly conical to cylindrical in shape, spire high, highly variable in sculpture, color, and banding (Fig. 5). Whorls somewhat flattened to moderately convex, occasionally weakly shouldered or with a subsutural ramp, suture weakly to moderately impressed. Aperture oval in shape, lip smooth, slightly sinuous. Spiral sculpture of numerous, fine striae, typically moderately to strongly developed and rarely indistinct, highly variable in strength and number; sporadic slightly elevated lirae. Axial sculpture of fine, sinuous growth lines, and plications on early whorls when preserved; plications regular and even, moderately to strongly developed, occasionally shouldered, orthocline, opisthocline, to strongly opisthocyrt, sometimes extending full length of shell, but frequently obsolete on body whorl; may be thickened or beaded at intersections with spiral striae. Shell black, dark brown, to olive or tan in color. Bands present or absent, one to three in number and variable in width, reddish-purple in color. Interior of aperture white or cream to dark purple in color, occasionally with yellowish-orange rim inside lip; bands when present visible inside aperture. Base of columella occasionally tinged reddish-purple.
Radula. Rachidian narrowly rectangular, wider than tall, with convex lower margin and a small, pointed, basal denticle at lower, outer corners ( Fig. 6). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp and two to three stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two to three inner and two to three outer, triangular denticles, and frequently a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal third to half of shafts; outer flanges extending almost to tooth bases, narrow on inner marginal teeth, broadening towards cutting edges on outer marginal teeth. Inner marginal teeth with five to six, and outer marginal teeth with six to seven flattened denticles.

Distribution and ecology
In small creeks to large rivers primarily west of the Cascades from the Olympic Peninsula of Washington in the north (Branson 1977) to the Willamette River drainage in south-central Oregon (Fig. 7A).

Remarks
Frest & Johannes (2010) refined the type locality of M. plicifera to the Multnomah Channel, which is indicated on some early maps as the second mouth of the 'Wahlamat' or Multnomah River. The terminal portion of the Willamette River near its confluence with the Columbia is also the type locality of  produced Henderson's type specimens of Goniobasis hemphilli . Sequalitchew Creek is considered a possible source of Gould's type material of Melania silicula, a Puget Sound tributary which flowed just to the north of the site of Fort Nisqually between 1833 and 1843, the Hudson's Bay Co. outpost on the shores of Puget Sound. It was the only settlement in the area at the time and was the first port of call for the U.S. Exploring Expedition, which was the source of Gould's types (Strong & Frest 2007;. Juga no longer occurs in Sequalitchew Creek, but near topotypic specimens from McAllister Creek ) and the Nisqually River (Strong & Whelan 2019) (Fig. 5A) also placed in this clade. Melania silicula was synonymized with plicifera by Pilsbry (1899), a view not followed by later authors. In earlier treatments, silicula was considered widespread in Washington and Oregon (e.g., Goodrich 1942;, Burch 1982), but more recently was considered a narrow-range endemic of southeastern Puget Sound (Strong & Frest 2007;Johannes 2010b). Juga hemphilli hemphilli and J. h. dallesensis were regarded as species incerta by Goodrich (1942) but recognized as valid by  and Burch (1982Burch ( , 1989. Campbell et al. (2016) noted the low genetic divergence of dallesensis from the nominotypical form but did not address their taxonomic status apart from concluding the small morphological differences in the latter could represent individual variation.  also considered both as valid, but the inclusion of the name J. h. dallesensis in a heading indicated that they had apparently considered it a possible synonym of J. (O.) bulbosa (Frest & Johannes 2010: 26). Juga hemphilli was recognized without subdivision by Turgeon et al. (1988Turgeon et al. ( , 1998 and Johnson et al. (2013). Thus, the synonymy of these two nominal species with plicifera here is new.
Melania rudens Reeve, 1860 was established without a locality. Tryon (1864) synonymized it with Goniobasis silicula but was later (Tryon 1865: 239) convinced of its validity and considered the species to range from Oregon to California in the Columbia and Sacramento Rivers. Goniobasis silicula rudens was recognized as valid by Henderson (1935aHenderson ( , 1936b) as a form from the Olympic Peninsula. However, most authors have synonymized it with silicula (e.g., Tryon 1873;Henderson 1929;Goodrich 1942;Burch 1982Burch , 1989) except Pilsbry (1899) who synonymized it with plicifera.  considered Juga (Juga) rudens a "dubious taxon", probably a synonym of J. silicula, and based on the original illustration of Reeve (1860: pl. 33 fig. 224) found the morphology closely comparable to that of specimens from the Nisqually River watershed and nearby tributaries of Puget Sound, the source of the types of Melania silicula. We agree and retain it here. Tryon (1865) established the varieties Goniobasis plicifera var. bulimoides and G. p. var. oregonensis, distinguished by the length of the shell and the density of revolving striae. He abandoned them soon thereafter, omitting them as either varieties or synonyms (Tryon 1866(Tryon , 1873. Henderson (1935aHenderson ( , 1936b acknowledged the "interminably intergrading varieties" and their rather arbitrary separation, yet inexplicably found the names useful, "in order to keep our ideas somewhat clear". Apart from Goodrich (1942) who synonymized the two with G. plicifera, other 20 th century authors have ignored the names.  thought Juga (Juga) plicifera bulimoides could be a valid large, slow river form, and J. (J.) p. oregonensis also likely to be valid. Campbell et al. (2016) noted the low genetic divergence of bulimoides and oregonensis from the nominotypical form and supported the synonymy of J. bulimoides with plicifera but did not address the taxonomic status of J. (J.) p. oregonensis, apart from concluding the small morphological differences could represent individual variation. Analysis of near topotypic specimens consistent with the morphology of the types (Strong & Whelan 2019) indicates that both subspecies represent morphological variation within the range of plicifera. , 1995a, 2010 (Gould, 1847) as circumscribed here. The specimen sequenced as J. (J.) draytonii by Campbell et al. (2016) placed in the same clade with J. (J.) plicifera plicifera; however, the morphology of the type material of draytonii is more consistent with the interpretation that it is a synonym of J. bulbosa (see account below).

Distribution
Several historical records suggest that J. plicifera may once have occurred, at least sporadically, in the Columbia River drainage of southeastern Washington. Two of these date from the late 1800's and early 1900's [Walla Walla (USNM 119156; Lea Collection, Lady K. Douglas) and Wallula (USNM 109897; U.S. Fish Commission)] and their provenance is unreliable (Carpenter 1857: 162). Another lot collected in 1958 (USNM 795562; identified as J. hemphilli) places the species in a spring alongside the Snake River, a Columbia River tributary, in Whitman County of far eastern Washington, which lies far to the east of the known distribution. Moreover, this lot contains only preserved soft parts lacking shells, so the identification cannot be confirmed. However, an iNaturalist record from 2019 east of Pendleton, Oregon, shows a plicate specimen that appears to be this species (https://www.inaturalist.org/observations/28180434) and demonstrates the species extends farther east than museum records suggest. Given the non-contiguous distribution of Juga in eastern Oregon and western Nevada, the occurrence of Juga at these distant sites should not be immediately discounted (Frest & Johannes 2010: 18), but we do not include them on our distribution map until they can be confirmed in modern surveys.

Description
Shell. Thin to moderately thick, large, reaching ~2.85 cm in length; turriform, narrowly conical to cylindrical in shape, spire height moderate to tall (Fig. 8). Whorls somewhat flattened to convex or angulate with a subsutural ramp, suture weakly to deeply impressed. Aperture oval in shape, lip smooth to crenate, simple to slightly sinuous. Spiral sculpture absent or present, of thickened, scalloped lirae, barely elevated to prominent, highly variable in number and sinuosity, dividing whorl into intervening flattened areas or grooves. Axial sculpture of fine, orthocline, or weakly opisthocyrt to sinuous growth lines; plications lacking. Shell black, brown or reddish brown, rarely yellowish green in color, occasionally with a lighter subsutural band; bands otherwise lacking. Interior of aperture light brown to white in color.
Radula. Rachidian narrowly rectangular, wider than tall, basal margin slightly concave between bluntly rounded median and lateral projections; basal denticles lacking or vestigial (Fig. 9). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp, and two stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two inner and three to four outer, triangular denticles, and occasionally a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal third to half of shafts; broad outer flanges extending almost to tooth bases. Inner marginal teeth with five and outer marginal teeth with six flattened denticles. See also Strong & Frest (2007).

Distribution and ecology
In springs, spring runs, and spring-fed creeks from Modoc and Lassen Counties in the upper Pit River drainage in northern California and in Great Basin drainages from northeastern California (Lassen County, Honey Lake basin), southeastern Oregon (Lake County), and northwestern Nevada, primarily in Washoe County, and adjacent parts of western Humboldt County (Fig. 7B).

Remarks
The type material of Melania acutifilosa was collected during the geographical surveys of the territory of the United States west of the 100 th meridian (Wheeler 1879). The type locality is "Eagle Lake" (Stearns 1890), later corrected by  to head of Willow Creek without justification. Strong & Frest (2007) followed this, explaining that no populations are currently found in Eagle Lake or in the small tributaries that flow into the lake during winter. Moreover, specimens of Juga have not been recorded from the lake itself during subsequent collecting efforts (e.g., by J. Maillard in 1923;Hanna 1924) nor from drift and dredged material ) but have been reported from several unnamed springs and creeks nearby in collections made by R.C. McGregor in 1898 (Pilsbry 1899; in the collections of the ANSP).  noted that  did not distinguish between the "headwaters" or "Murrer's Meadows" as the source of the types. Given their view that different taxonomical species are found in the headwaters versus further downstream, they concluded the lirate types were most likely from the head of Willow Creek. This is likely correct, as Willow Spring at the head of Willow Creek in Murrer's Upper Meadow was the site of an altitude measurement taken during the survey (Wheeler 1879: 130) and lies roughly two miles to the east of the shore of Eagle Lake.  considered USNM 198955 from "Willow Fork" also collected during the expedition as possible topotypes; the lot was annotated "Eagle Lake vicinity" by J.P.E. Morrison who separated the original lot into lirate and smooth forms (USNM 198955 and USNM 198955a), which are here considered conspecific. This is a highly variable species, ranging from lirate to smooth forms, and like J. canella sp. nov. with which this species has been frequently confused, these forms can co-occur at a single site. Juga laurae and J. interioris have been considered valid species in recent classifications Burch 1982Burch , 1989Turgeon et al. 1988Turgeon et al. , 1998Johnson et al. 2013). However, molecular data (Strong & Whelan 2019) show that topotypic specimens (Fig. 8F-G) of these two nominal species are conspecific with disjunct populations from adjacent parts of Oregon and California, including from the type locality of M. acutifilosa (Fig. 8D-E), and their synonymy with J. acutifilosa here is new. Juga laurae and J. interioris were established by Goodrich (1944), who found them so wanting in definite characters of the shell, operculum, and radula that he was at first hesitant to describe them as new (Goodrich 1935), but later upon doing so, felt unable to ascertain their affinities (Goodrich 1944: 1). Despite statements to the contrary (Frest & Johannes 2010: 38),  did not mention nor explicitly synonymize the two with J. nigrina in his checklist of freshwater mollusks of California. The range for nigrina, given by Taylor (1981: 149) as "northern California and adjacent parts of Oregon and Nevada", might imply inclusion of laurae and interioris, but is ambiguous.

Distribution
The species as redefined herein occurs in the upper Pit River drainage in northern California and Great Basin drainages in northeastern California, southeastern Oregon, and northwestern Nevada. Based on the presence of elevated spiral lirae, J. acutifilosa erroneously has been considered to extend to Siskiyou County, California, and Jackson County in south-central Oregon , 2000a, 2010Furnish 2007;Johnson et al. 2013), although  acknowledged the species to be composite. As defined by , 2000a, 2010 (Strong & Frest 2007;Campbell et al. 2016). The species is more broadly distributed than previously appreciated and includes populations of smooth, dark morphs attributed to J. interioris and J. laurae from northwestern Nevada.

Common name
The common name for this species is the Scalloped Juga , 2000a. Turgeon et al. (1988Turgeon et al. ( , 1998 incorrectly referred to this species as the Topaz Juga (= J. occata) which was followed by , 2010 and Johnson et al. (2013). This may have been the result of the erroneous synonymy of Goniobasis acutifilosa pittensis with the frequently reddish-brown J. acutifilosa rather than with J. occata, for which a green-or yellow-brown coloration is more typical ; see J. occata below). Synonyms have been known as the Oasis Juga (for J. laurae) and Smooth Juga (for J. interioris) (e.g., Turgeon et al. 1988Turgeon et al. , 1998Johnson et al. 2013). As mentioned above, populations from south-central Oregon , 2000a

Description
Shell. Thick, large, reaching ~2.75 cm in length; turriform, narrowly conical in shape, spire height moderate to tall (Fig. 10). Whorls somewhat flattened to moderately convex, suture weakly to moderately impressed. Aperture oval in shape, lip smooth and simple. Spiral sculpture of numerous fine striae, usually indistinct but occasionally weakly to moderately developed, variable in strength and number; sporadic indistinct elevated lirae. Axial sculpture of fine, sinuous growth lines; plications present or absent, confined to upper part of spire; plications regular and even, weakly to moderately developed, occasionally shouldered, orthocline to weakly opisthocyrt, variable in strength and number. Shell black, dark or reddish brown, to tan in color, occasionally with a lighter subsutural band; reddish brown bands present or absent, one to three in number and variable in width. Interior of aperture white, yellowishbrown to dark purple in color; bands when present visible inside aperture.
Radula. Rachidian narrowly rectangular, wider than tall, basal margin flattened between bluntly rounded median and lateral projections; basal denticles lacking or vestigial (Fig. 11). Upper margin slightly concave with cutting edge bearing central elongate, conical cusp, and two stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two inner and two to three outer, triangular denticles, and occasionally a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal third of inner marginal teeth and extending almost to tooth bases of outer marginal teeth; broad outer flanges extending almost to tooth bases. Inner marginal teeth with four and outer marginal teeth with four to five flattened denticles.

Distribution and ecology
In springs, spring runs, and spring-fed creeks to large rivers in the central and eastern Columbia River Gorge drainages in north-central Oregon and south-central Washington, including the Mt. Hood National Forest, Columbia Gorge National Scenic Area, and Lower Deschutes River below Pelton Dam (Fig. 7C).

Remarks
The type locality of Goniobasis bairdiana and G. draytonii, both ostensibly from the Columbia River at Fort George [= Astoria] collected by J. Drayton, is likely erroneous , as the species does not extend to the western Columbia Gorge and there is no evidence it ever has. All sequenced specimens and historical lots in museum collections from the terminal part of the Columbia River are conspecific with Juga plicifera (e.g., Fig. 5K-M). Joseph Drayton was the expedition's artist and travelled up the Columbia Gorge as far as Fort Walla Walla with a Hudson Bay Company boat bringing supplies to the forts up the river (Smith 1937;, and thus the types could have come from anywhere along this route, likely from tributaries of the main stem Columbia in the central to eastern part of the gorge. The paralectotype lot of draytonii from "Walla" [sic, Walla Walla] (USNM 119124) received via Lady K. Douglas lies well to the east of the known range but its provenance is unreliable (Carpenter 1857: 162).  Burch 1982Burch , 1989 fig. 452; Turgeon et al. 1988Turgeon et al. , 1998) (see below). This confusion was caused, at least in part, by the paucity of historical material in museum collections, and what little there is in some cases contains mixtures of the two species. For example, the paralectotype lot MCZ 169068 is a mixture of bulbosa and newberryi, as is USNM 5563 which contains Gould's (1860: pl. 10 fig. 163-163a) figured specimen of bulbosa (Fig. 10E-F). Strong & Frest (2007) removed newberryi from the synonymy of bulbosa, leaving the status of the latter somewhat unresolved as a likely valid species; this was followed by  who reported that they had been unable to recollect this form anywhere in the Deschutes River drainage or Columbia Gorge; accordingly, Campbell et al. (2016) reported they could not assess its status. Johnson et al. (2013) considered bulbosa a valid species and it was indicated to be endangered under AFS criteria and critically imperiled under NatureServe's global conservation status ranks but tallied as extinct : table 1) .
After comprehensive review of the type material in comparison to the morphology of sequenced specimens, we consider the smooth, unbanded lectotypes of Melania bulbosa (Fig. 10A) and Goniobasis draytonii (Fig. 10C) to fall within the range of variation of Juga species 2 sensu Strong & Whelan (2019) in size, proportion, profile, and sculpture. However, populations precisely matching the distinctive morphology of the types of bulbosa have not been recollected thus far (Strong & Frest 2007;) and may no longer be extant. Frest & Johannes (2010: 26) noted the similarity of the types of bulbosa and of draytonii but distinguished the latter on the basis of its more elongate spire and more numerous whorls after decollation. , 1995a considered that their J. (J.) n. sp. 1 (Brown Juga) could match Lea's types of draytonii, but their composite concept of the species was distributed from the central and western Columbia Gorge in both Oregon and Washington, including the Mt. Hood National Forest, and thus would include individuals of both J. bulbosa and J. plicifera as circumscribed here. The specimen sequenced as J. (J.) draytonii by Campbell et al. (2016) placed in the same clade with J. (J.) plicifera plicifera; however, the morphology of the type material of draytonii is consistent with the interpretation that it is a synonym of J. bulbosa. Even the comparatively smooth forms of J. plicifera in small Columbia River tributaries from Washington (e.g., Fig. 5H-J) can be readily distinguished from J. bulbosa by their larger size at adulthood, more cylindrical shape, higher spire, and more shouldered whorls. In Columbia River tributaries on the Oregon side, plicifera tends to be quite large and heavily sculptured (e.g., Fig. 5N-O, R-S) and that much more distinct from bulbosa. When preserved, the plications in bulbosa are less conspicuous and confined to the upper spire.
Juga bulbosa also includes what has been referred to as J. (Juga) bairdiana by  and Campbell et al. (2016). With its plicate early whorls, bairdiana has been viewed as a synonym of plicifera (Pilsbry 1899;Walker 1918) or silicula (Goodrich 1942) or as a subspecies of silicula (Henderson 1935a(Henderson , 1936b, but sequenced specimens morphologically identical to the type of bairdiana (e.g., Fig. 10H) (Strong & Whelan 2019) confirm it is conspecific with bulbosa as circumscribed here. Near topotypic specimens (Fig. 10I-J) from the Deschutes River of what has been referred to as J. (J.) hemphilli maupinensis Burch 1982Burch , 1989Campbell et al. 2016) are also conspecific with bulbosa.

Distribution
As mentioned, well localized, historical specimens of this species are uncommon in museum collections. In the USNM, apart from the material collected for this study, it is represented by four lots collected between 1971 and 1983. The remaining 13 lots, including the type material, were collected in the early 1900's or earlier and are all poorly or mislocalized: six lots are localized simply to "Oregon", and one lot said to be from the Willamette River (USNM 321825) is mislocalized. Another lot from Sullivan's Island in the Columbia River (USNM 468428) was catalogued in late 1936 with no collecting date and occurs slightly farther west than the species' known range, but is comprised of bleached and worn, deadcollected specimens that may have been transported. Goniobasis bulbosa was erroneously reported by Pilsbry (1899) to occur in the Owyhee River, a Snake River tributary, based on a mislocalized specimen record in the ANSP (ANSP 27561), an error perpetuated until recently (e.g., Burch 1982Burch , 1989; see Frest & Johannes 1995a). This lot was interpreted as nigrina sensu lato by  but is a mixed lot of bulbosa and newberryi. Surveys in the Owyhee River drainage and from archeological sites in this drainage have not produced any Juga (Frest & Johannes 2010: 26). A lot cited by Henderson (1929Henderson ( , 1936bUCM 15814) from Ahtanum Creek, Union Gap, in Yakima County, Washington, that he attributed to Goniobasis draytonii and G. rubiginosa, appears to be J. bulbosa as circumscribed herein, and which Frest & Johannes (2010: 35) stated to resemble specimens from the Klickitat Plateau, Washington. One lot of 50 specimens in the ANSP database, from Union Gap in the Yakima area, could not be found (P. Callomon, pers. com.). Attempts to recollect Juga in this area were unsuccessful (Frest & Johannes 1995a: 246). Campbell et al. (2016: fig. 1) , 1995a, 2010Furnish 2005;Duncan 2008;Johannes 2015). Juga bulbosa also includes what has been referred to as the Basalt Juga [= Juga (Oreobasis) n. sp. 2] (Frest & Johannes 1999;Duncan 2008;Johannes 2015), which has been afforded federal protection under the "survey and manage" provisions of the Northwest Forest Plan (USDA andUSDI 1994, 2000) and petitioned for federal listing under the U.S. Endangered Species Act (USFWS 2011). However, the 12-month finding on the petition concluded that the species could not be considered a listable entity pending the necessary genetic comparisons to establish its taxonomic validity (USFWS 2012). Given placement of the Basalt Juga as a synonym of this wider-ranging species, a listing decision can now be made but will require consideration of the full range of J. bulbosa. N.V. Whelan leg.; USNM 1295000 • 1 spm; same collection data as for preceding; GenBank: MK472116, MK464488; USNM 1294989 • 1 spm; same collection data as for preceding; GenBank: MK472117, MK464489, MK480731; USNM 1294990 • 1 spm; same collection data as for preceding; GenBank: MK472118, MK464490, MK480732; USNM 1294991 • 1 spm; same collection data as for preceding; GenBank: MK472119, MK464491; USNM 1294992 • 1 spm; same collection data as for preceding; GenBank: MK472120, MK464492; USNM 1294993 • 1 spm; same collection data as for preceding; GenBank: MK472121, MK464493; USNM 1294994 • 1 spm; same collection data as for preceding; GenBank: MK472122, MK464494, MK480733; USNM 1294995 • 1 spm; same collection data as for preceding; GenBank: MK472123, MK464495, MK480734; USNM 1294996 • 1 spm; same collection data as for preceding; GenBank: MK472124, MK464496, MK480735; USNM 1294997 • 1 spm; same collection data as for preceding; GenBank: MK472125, MK464497, MK480736; USNM 1294998 • 1 spm; same collection data as for preceding; GenBank: MK472126, MK464498; USNM 1294999.

Description
Shell. Thin, moderate in size, reaching ~1.5 cm in length; turriform, conical in shape, spire height moderate (Fig. 12). Whorls convex, suture moderately impressed. Aperture oval in shape, lip smooth, simple to slightly sinuous. Spiral sculpture of indistinct, fine striae, variable in strength and number. Axial sculpture of fine, orthocline to weakly opisthocyrt or sinuous growth lines; plications lacking. Shell dark brown to black, occasionally with a lighter subsutural band. Interior of aperture bluish in color, occasionally tinged with purple.
Radula. Rachidian broadly rectangular, wider than tall, with convex lower margin and projecting outer corners; basal denticles lacking or vestigial (Fig. 13). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp, and two to three stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two inner and two to three outer, triangular denticles, and frequently a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal half to two-thirds of shafts; broad outer flanges extending almost to tooth bases. Inner marginal teeth with ~four and outer marginal teeth with ~five flattened denticles.

Distribution and ecology
In springs and spring runs of the John Day River drainage, northeastern Oregon (Fig. 14A).

Remarks
This species is characterized by its simple, smooth, dark, lightly constructed shell, without distinguishing sculpture; the only known populations are rather uniform in shape and size.

Distribution
Juga caerulea sp. nov. is a highly disjunct and restricted species, occurring in springs and spring runs from a few sites within a single spring complex in Phipps Meadow, the headwaters of the Middle Fork of the John Day River in the Malheur National Forest. One lot collected in 1939 (USNM 473801) indicates that historically it may have occurred in small streams in the area; Morrison (1954: 361, 384, pl. 11 fig. 5) identified these specimens as Oxytrema bulbosa and provided a sketch of the head-foot of a female to show the egg laying groove and ovipositor. However, recent efforts to locate the species elsewhere in the Blue Mountains have been unsuccessful (Frest & Johannes 1995a). Phipps Meadow, the source of the type material, has been heavily affected by grazing and Frest & Johannes (1995a) considered existing surveys were sufficient to merit a status of Endangered at the Federal or State level. The Blue Mountain Land Trust recently purchased Phipps Meadow with the goal of protecting and restoring the meadow's riparian habitat (https://bmlt.org/news/phipps-meadow).

Description
Shell. Thin, small to moderate in size, usually not exceeding ~1.5 cm in length, rarely up to ~2.4 cm; turriform, broadly to elongately conical in shape, spire height low to moderate (Fig. 15). Whorls convex to angulate with a subsutural ramp, occasionally shouldered, suture moderately to deeply impressed. Body whorl usually inflated. Aperture oval in shape, lip smooth to crenate, simple to weakly sinuous. Spiral sculpture absent or present, of thickened lirae, smooth to slightly sinuous, barely elevated to prominent, variable in number, dividing whorl into intervening flattened areas or grooves. Axial sculpture of fine, weakly prosocline to opisthocyrt or sinuous growth lines; plications lacking. Shell black, dark purplish to reddish cinnamon brown or tan in color, infrequently with irregular streaks of reddish purple or a lighter subsutural band. Interior of aperture cream to dark purple in color.
Radula. Rachidian squarish, slightly wider than tall, with weakly v-shaped lower margin and projecting outer corners; basal denticles lacking (Fig. 16). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp, and two to four stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two to three inner and three to four outer, triangular denticles, and frequently a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal half to two-thirds of shafts; broad outer flanges extending almost to tooth bases. Inner marginal teeth with ~three and outer marginal teeth with three to five flattened denticles.

Distribution and ecology
Primarily in springs, spring runs, and spring-fed creeks of northern California in Shasta River drainages and adjacent parts of the upper Sacramento River drainage in Siskiyou and Shasta Counties, and of south-central Oregon in upper Klamath River drainages in Jackson County, including sites in the Cascade-Siskiyou National Monument (Fig. 14B).

Remarks
Juga canella sp. nov. is comprised of smooth and lirate forms that can co-occur at the same site and possess the same COI haplotype (Strong & Whelan 2019: fig. 4). In the northern part of its range, J. canella can be distinguished from J. nigrina, which is typically banded and sculptured with spiral striae and plications on the upper whorls, more cylindrical with a narrower spire angle, and larger in size at adulthood (see J. nigrina below).

Distribution
Based on sequenced specimens, the confirmed southern extent of the range is from springs north of Mossbrae Falls in the vicinity of Dunsmuir in southern Siskiyou County, California . At least historically, the species extended slightly further south as represented by one lot of five specimens collected in 1937 at Conant [= Castella] in northern Shasta County (UF 192876). In the southern part of the range, the species occurs in the part of the Sacramento River drainage affected by the Cantara Loop chemical spill in 1991 . The species is associated primarily with springs and spring runs where it survived the disaster, but Frest & Johannes (1999) noted rare populations associated with subaqueous springs in the main stem of the Sacramento River which would have been extirpated by the spill.

Common name
The common name for this species is the Cinnamon Juga , 1999Duncan 2008  , which previously was considered restricted to the upper Sacramento River drainage in Siskiyou County, California, and had been afforded federal protection under the "survey and manage" provisions of the Northwest Forest Plan (USDA andUSDI 1994, 2000) and petitioned for federal listing (USFWS 2011). However, the 12-month finding on the petition concluded that the species could not be considered a listable entity pending the necessary genetic comparisons to establish its taxonomic validity (USFWS 2012).

Description
Shell. Thin, moderate in size, reaching ~2 cm in length; turriform, conical in shape, spire height moderate (Fig. 17). Whorls convex, suture moderately impressed. Aperture oval in shape, lip smooth, simple to weakly sinuous. Spiral sculpture of numerous, indistinct, fine striae. Axial sculpture of fine, weakly prosocline to opisthocyrt or sinuous growth lines; irregular varices occasionally present confined to upper spire. Shell light brown to dark purplish-or reddish-brown, occasionally with a lighter subsutural band. Interior of aperture light, yellowish brown to dark purple.
Radula. Rachidian narrowly rectangular, wider than tall, basal margin flattened, with slight, bluntly rounded median and lateral projections; basal denticles lacking or vestigial (Fig. 18). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp, and two to three stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by ~three inner and three to five outer, triangular denticles, and frequently a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal half to third of inner marginal teeth and extending almost to tooth bases of outer marginal teeth; broad outer flanges extending almost to tooth bases. Inner marginal teeth with ~four and outer marginal teeth with ~five flattened denticles.

Distribution and ecology
Primarily in springs, spring runs, and small creeks in the southern Pit River system; possibly extending into larger creeks and rivers in eastern Sacramento River tributaries and the northern Mokelumne River watershed of the Sierra Nevada (Fig. 14C).

Remarks
Given the uncertainty of the circumscription of this species in the southern part of its range (see below), the preceding description is based on sequenced and topotypic specimens. Although not present in all specimens, the species may be distinguished by the presence of irregular varices on the upper whorls of some specimens (e.g., Fig. 17V, X-Y). These can be seen in the sequenced holotype and topotypic specimens (Fig. 17A, U) and are more irregular and widely spaced than the plications seen in J. nigrina with which it overlaps in distribution in the western part of its range (see J. nigrina below).

Distribution
The main part of the distribution of J. douglasi sp. nov. lies in the southern Pit River drainages in Shasta and Lassen Counties where it overlaps with J. occata, although individuals of the two species are rarely found in syntopy; only three lots with mixtures of the two were found in the USNM collections [USNM 1111864, USNM 1665623 (ex USNM 1111864); USNM 892372, USNM 1665624 (ex USNM Populations from Sacramento River drainages of the western foothills of the Sierra Nevada have been attributed primarily to J. nigrina (e.g., Lowe 1916;Brim Box 2002;Brim Box et al. 2005), rarely to J. interioris (e.g., Lee et al. 2006;Ó Foighil et al. 2009), and more recently were noted to comprise at least one new species (Frest & Johannes 2007). These are difficult to identify with certainty in the absence of molecular data but are here cautiously interpreted as representing J. douglasi sp. nov. When preserved, the early teleoconch is typically smooth, narrow, with convex whorls and a deeply impressed suture, and sometimes (CASIZ 165961, CASIZ 166013) shows the varices seen more frequently in the northwest part of the range. The teleoconchs are usually smooth, but occasionally spirally grooved or with indistinct spiral striae and are rarely banded. If these records can be verified as conspecific with J. douglasi, scattered museum records place the species, at least historically, in eastern Sacramento River drainages in Butte, Sierra, Nevada, El Dorado, and Sacramento Counties in the Feather River, Yuba River, and American River Basins. These areas coincide with the Sierra Nevada goldfields and were heavily affected by placer mining activities including hydraulic mining and dredging. However, modern museum records from the mid 1990's and surveys by Frest & Johannes (2007;as Juga n. spp.) confirm that Juga is surviving in highly fragmented populations in the southern Lassen National Forest, the Plumas National Forest, and the Tahoe National Forest in Nevada County (CASIZ 112152, 113099, 113100). A 2018 iNaturalist record (https://www.inaturalist.org/observations/15172449) from the Cosumnes River, El Dorado County, indicates that Juga populations are persisting in the Mokelumne River watershed, which borders the Sacramento River watershed to the south. One historical lot (ANSP 145847) from Strawberry Creek on the UC Berkeley campus in the East San Francisco Bay Area contains spirally grooved specimens (Fig. 17T) similar to some from Table Mountain in Butte County [USNM 119284 (Fig. 17Q), ANSP 27568] and North San Juan in Nevada County [CASIZ 30310 (Fig. 17R, Z)] and is hypothesized also to be conspecific with J. douglasi. However, given the range of morphological variation seen in species of Juga, it is possible that populations from the Sierra Nevada represent mixtures of J. occata and J. douglasi, or an as yet undescribed form.

Description
Shell. Moderately thick, small for the genus, reaching ~1.5 cm in length; broadly to elongately conical in shape, spire height low to moderate (Fig. 19). Whorls convex to somewhat flattened, shouldered, suture deeply impressed, body whorl usually inflated. Aperture broadly oval in shape, lip smooth, simple. Spiral sculpture lacking. Axial sculpture of fine, weakly prosocline to opisthocyrt growth lines; plications lacking. Shell dark purple to tan in color, usually with three reddish brown bands, variable in width. Interior of aperture white to dark purple in color; bands when present visible inside aperture. Columella occasionally tinged reddish-purple.
Radula. Rachidian narrowly rectangular, wider than tall, with angular to convex lower margin and projecting outer corners; basal denticles lacking or vestigial (Fig. 20). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp, and two to three stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two to three inner and two to three outer, triangular denticles, and frequently a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal half to two-thirds of shafts; broad outer flanges extending almost to tooth bases. Inner marginal teeth with four to five and outer marginal teeth with six to seven flattened denticles. See also Strong & Frest (2007).

Distribution and ecology
In the lower Middle and Lower Deschutes River in central Oregon, and associated springs, spring runs and spring-fed creeks in the Deschutes River drainage (Fig. 21A). Tryon (1864Tryon ( , 1865Tryon ( , 1866Tryon ( , 1873 viewed Goniobasis newberryi as valid and distinct but remarked that this species and G. bulbosa were "exactly similar in outline" (Tryon 1864: 53;1865: 246;1873: 255) and "certainly extremely closely allied" (Tryon 1865: 245), differing only in the presence or absence of bands (Tryon 1866: 34). Pilsbry (1899) subsequently synonymized the two, which was followed by most authors and resulted in confusion about the identity and distribution of Juga newberryi for over 100 years (see Strong & Frest 2007). Most usages of the name bulbosa in the literature in fact refer to J. newberryi (e.g., Tryon 1865: fig. 17;1866: fig. 217;1873: fig. 496;Roscoe 1963: pl. 4 figs 5-6;Burch & Tottenham 1980: fig. 452;Burch 1982Burch , 1989Turgeon et al. 1988Turgeon et al. , 1998. This confusion was compounded by the fact that the species is inexplicably rare in museum collections (see e.g., Henderson 1936b) despite occurring in abundance at some sites. Apart from the types and material collected for the present research, holdings of newberryi in the USNM collections include only three lots, one from the U.S. Exploring Expedition, one collected in 1971 and one in 2000. What little museum material there is in some cases contains mixtures of the two species (see account for J. bulbosa, above).

Remarks
Although Frest & Johannes (2010: 26) could not determine its identity, the specimen figured by Tryon as Goniobasis bulbosa (1865: fig. 17;1866: fig. 217;1873: fig. 496) is the larger of the two specimens in USNM 12174 (Fig. 19N), entered in the handwritten ledger catalogue on May 10, 1876, identified as "Strepoma bulbosa Gould" with no other information than being from "Oregon" [Territory]. Tryon (1865: 246) claimed the specimen to be, "the largest I have seen, and considerably exceeds the dimensions of Dr. Gould's type specimen". There can be no doubt that it represents a specimen of J. newberryi given the low spire and inflated body whorl. Paralectotype lot MCZ 169068 comprises a mixture of bulbosa and newberryi, as does USNM 5563 which contains Gould's (1860: fig. 163-163a) figured specimen of bulbosa ( Fig. 10E-F).
The erroneous synonymy of newberryi with bulbosa notwithstanding, this is a distinctive Deschutes River endemic, particularly the low spired, inflated morph. However, banded subadults of J. bulbosa (e.g., Fig. 10S) may be confused for J. newberryi without careful scrutiny when they co-occur (e.g., The early teleoconchs of bulbosa are frequently eroded but when preserved may be plicate, whereas they are invariably smooth in newberryi. The tall slender morph of newberryi (Fig. 19G-H, L-M) also may be difficult to differentiate from bulbosa as the banding patterns can be quite similar. One lot containing dead-collected specimens from the confluence of Willow Creek and the Deschutes River (USNM 905120; Fig. 19L-M) compares favorably in size and proportion with specimens sequenced from Opal Springs (Fig. 19G-H) and are considered to represent newberryi. Specimens of bulbosa sequenced nearby generally have a less deeply impressed suture and are larger in size at adulthood (e.g., Fig. 10P). There are banded and unbanded morphs of both species, even at a single site, but unbanded morphs of newberryi are rare and are usually quite dark, not the tan to golden base color as seen in most historical lots. It is uncertain whether these golden, unbanded forms are merely faded or represent a local variant that has not been recollected.

Distribution
The type locality of newberryi is the Upper Deschutes River, which is considered the region upstream of Bend, Oregon, but there is no evidence it ever extended this far upriver. Frest & Johannes (1995a, 2010 and Strong & Frest (2007) considered the types to have originated from near Bend without justification and indicated the species occurs sporadically below Pelton Dam to roughly 6 miles above the mouth where it is replaced by "J. (J.) plicifera" (= J. bulbosa as circumscribed herein). However, some spring dwelling forms (e.g., Opal Springs, Oak Springs) previously considered an undescribed species (see below) are conspecific with J. newberryi (Strong & Whelan 2019) and place the species above Pelton Dam.

Description
Shell. Thin to moderately thick, large, usually not exceeding ~2.5 cm, exceptionally reaching ~3.75 cm in length; turriform, narrowly conical to cylindrical in shape, spire moderate to high, highly variable in sculpture, color, and banding (Fig. 23). Whorls somewhat flattened to convex, occasionally weakly shouldered or with a subsutural ramp, suture weakly to deeply impressed. Aperture oval in shape, occasionally flattened at the base, lip smooth, simple to slightly sinuous. Spiral sculpture of fine striae, indistinct to moderately developed, highly variable in strength and number; later whorls occasionally with few, indistinct elevated lirae. Axial sculpture of fine, orthocline, weakly opisthocyrt to sinuous growth lines; plications present or absent, confined to upper part of spire; plications regular to somewhat irregular, weakly to moderately developed, occasionally shouldered, orthocline to moderately opisthocyrt; may be thickened or beaded at intersections with spiral striae. Shell black, dark brown, to olive, tan or yellowish in color. Bands present or absent, one to three in number and variable in width, reddish-purple in color. Interior of aperture white or cream to dark purple in color. Base of columella occasionally tinged reddish-purple Radula. Rachidian narrowly rectangular, wider than tall, with convex lower margin and small, bluntly pointed, basal denticles at lower, outer corners (Fig. 24). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp, and two to three stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two to three inner and two to three outer, triangular denticles, and occasionally a membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal half to two-thirds of shafts; broad outer flanges extending almost to tooth bases. Inner marginal teeth with ~five, and outer marginal teeth with six to seven flattened denticles.

Distribution and ecology
In small creeks to large rivers primarily in coastal drainages from south-central Oregon to central California (Fig. 21B).
Although it is not known precisely where in Clear Creek the types of Melania nigrina originated, this creek has been severely affected by impoundment and gold dredging and many sites still lack Juga . However, refugial populations in several large tributaries seem to be repopulating the main course near their junctions with Clear Creek.  noted the discrepancy between Lea's (1856Lea's ( , 1863aLea's ( , 1863b description and the type specimens (Fig. 22A), which do not appear as nearly black and polished with a dark purple interior as the description would suggest. Near topotypic specimens from Clear Creek at French Gulch (Fig. 23T) were included in the analysis of Strong & Whelan (2019), which showed a range of variation from those yellow-brown in color with a light interior similar to the type, to those black in color with a dark purple interior (Fig. 23U) matching the original description.
The type locality of Melania shastaensis was indicated to be Shasta and Scott Rivers, California (Lea 1856). Lea (1863aLea ( , 1863b later added "Fort Umpqua, O.T. [Oregon Territory]" to the list of habitats with the Smithsonian as collector, which refers to USNM 119286 from the Lea collection. However, this material has no type status as it was not originally included. Henderson (1935aHenderson ( , 1936b questioned whether the original type locality was erroneous, having seen no material from the Shasta River that matched the description, and considered the types more similar to material from the Umpqua River, an opinion shared by . Henderson submitted specimens from the Shasta, Klamath and Umpqua Rivers to the USNM for comparison with the type of shastaensis and received the following reply from curator Harald Rehder, "[the types of Goniobasis shastaensis Lea] are more like those from the Umpqua River. […] Whether Lea's type lot (from Scott and Shasta Rivers) really came from either or both of those rivers, or whether we are here dealing with a confusion of localities, I cannot tell" (Henderson 1935a: 95;1936b: 276). Owing to his doubts over the precision of the type locality, Henderson (1935a) described material in his possession from the Shasta River as Goniobasis yrekaensis. Henderson (1936b) later reported receiving specimens from the Scott River that agreed well with the original description of shastaensis, as did specimens from the Umpqua River drainage and elsewhere in western Oregon. Efforts to recollect from the Scott River were unsuccessful . Ultimately, however, the ambiguity is of little consequence as the same taxonomical species (J. nigrina) is found in both the Klamath and Umpqua River drainages.
The type locality of Melania circumlineata is the Mission San Antonio in Monterey County, California, but is widely assumed to be in error (Henderson 1932; as it lies far to the south of the documented distribution of Recent Juga (Fig. 21B). It was not infrequent in those times that specimens brought back to natural history museums "from the seats of trade" (Carpenter 1857: 162), or from the seats of worship (e.g., Neubert et al. 2009), took incorrect provenance. Cooper (1894) indicated San Antonio Creek as the southern extent of Goniobasis circumlineata. This creek, which forms part of the boundary between Marin and Sonoma Counties, is a tributary of the Petaluma River, which flows into the northwestern corner of San Pablo Bay. Henderson (1932) quoted a personal communication from G.D. Hanna who pointed out that there are many San Antonio Creeks in California, but agreed that the one cited by Cooper may be the source of the type material. Hanna referred to an unconfirmed report of a chapel on the San Antonio Rancho at the head of the creek. Several museum lots (e.g., Fig. 23A') collected in southern Sonoma and Napa Counties are morphologically similar in size, shape, color and proportion to the lectotype of circumlineata. Pilsbry (1899) and Walker (1918) considered it to be likely only a variety of nigrina;  agreed that the type may be a decollate "nigrina" s. lat. Campbell et al. (2016: supp. file 1) reported this species could represent a number of smooth-shelled forms but were not able to analyze it. In addition to specimens from Mission San Antonio and Shasta County, California, both received from W. Newcomb, Tryon's (1865) concept of Goniobasis circumlineata included specimens collected by J.S. Newberry from the Pit River, and specimens from J.H. Thomson from the Feather River. Possible type material from the latter two localities has not been located and could potentially represent Juga occata, J. douglasi sp. nov., or both, but not J. nigrina, which does not extend that far east. Tryon (1873) later omitted circumlineata without comment and did not reproduce his earlier figures.
Attempts to locate type material of Melania californica have been unsuccessful. Clessin's collection was in Stuttgart, Germany, and was reportedly destroyed during World War II (Tomlin 1947: 288). Although parts of the collection evidently remain intact in the Stuttgart Museum, no types of this species are found there (I. Richling, pers. com.). Clessin (1882) attributed the locality information ("California") as communicated ("com." = communicavit) from H. von Heimburg of Oldenburg. Parts of von Heimburg's collection, particularly the freshwater parts, were purchased and re-assembled by C. Bosch, whose collection was received by the Senckenberg in 1962 (Zilch 1967). However, there is no type or topotypic material of this species in the Senckenberg (J. Sigwart, R. Janssen, pers. com.). Thus, on the merits of the originally published figure, we tentatively consider californica to be a synonym of nigrina. This synonymy was first proposed by Pilsbry (1899) and followed by Walker (1918), Henderson (1929Henderson ( , 1935aHenderson ( , 1936b, and .  found  synonymy with nigrina to be plausible but noted that it could be a nigrina-like form and suggested the common name California Juga. Campbell et al. (2016: supp. file 1) reported this species could represent a number of smooth-shelled forms but were not able to analyze it. Other authors have ignored the name.
Topotypic or near topotypic specimens for all five of Henderson's (1935a) nominal species established from northern California (Goniobasis chacei, G. coquillensis, G. orickensis, G. yrekaensis, and G. y. obscura) were included in the molecular analysis of Strong & Whelan (2019) (Fig. 23F, M-N, S, V-W) and are conspecific with topotypic specimens of nigrina (Fig. 23T-U). All five were regarded as species incerta by Goodrich (1942).  and Burch (1982Burch ( , 1989 did not mention any of them; nor did Turgeon et al. (1988Turgeon et al. ( , 1998.  considered only Juga (Oreobasis) chacei and J. (O.) orickensis as valid, of which only the former was retained in the list of Johnson et al. (2013).  considered all as valid, or potentially so, except yrekaensis obscura, which they synonymized with yrekaensis. Campbell et al. (2016: supp. file 1) supported the synonymy of obscura with yrekaensis but they did not address the taxonomic status of Henderson's other nominal species. Thus, the explicit synonymy of all five nominal species with nigrina here is new.
Specimens identified as Juga (Oreobasis) "nigrina" from the Upper Klamath River drainage by Frest & Johannes (1998) and Johannes (2015) are hypothesized here to represent true nigrina, but this will require confirmation with molecular data. Frest & Johannes (1998 reported that they had found no ribbed forms in this area. However, USNM 334391 from Klamath Falls is a lot of two juvenile specimens which display regular plications typical of nigrina. The other three historical lots from Klamath County are all eroded but are rather high spired and cylindrical with a moderately impressed suture and are cautiously interpreted as representing true nigrina as well. However, it is possible they could represent a mixture of nigrina and smooth forms of J. canella sp. nov., which would extend the distribution of the latter to the east. The OTU referred to as Juga (Oreobasis) "nigrina"  = Schoolhouse Meadow Juga) and later as Juga (O.) n. sp. (Johannes 2013a = Spring Creek Juga) from the Cascade-Siskiyou National Monument comprises smooth forms of J. canella. The OTU referred to as scalloped lirae, barely elevated to prominent, highly variable in number and sinuosity, dividing whorl into intervening flattened areas or grooves. Axial sculpture of fine, weakly opisthocyrt to sinuous growth lines; plications lacking. Shell dark to reddish brown, to yellowish green in color, occasionally with a lighter subsutural band; bands otherwise lacking. Interior of aperture light brown to white in color.
Radula. Rachidian squarish, slightly wider than tall, with weakly v-shaped lower margin and projecting outer corners; basal denticles lacking or vestigial (Fig. 26). Upper margin slightly concave with cutting edge bearing central, elongate conical cusp, and two to three stout, conical denticles on each side. Lateral teeth with prominent triangular cusp flanked by two to three inner and two to three outer, triangular denticles, and frequently a large, membranous outermost denticle. Marginal teeth with broadly rounded cutting edges and long, slender, flattened shafts with membranous flanges along inner and outer edges. Narrow inner flanges along distal third to quarter of inner marginal teeth and distal two-thirds of outer marginal teeth; broad outer flanges extending almost to tooth bases. Inner marginal teeth with three to four and outer marginal teeth with four to five flattened denticles.

Distribution and ecology
In spring-fed creeks to large rivers and lakes, currently restricted to the Pit River system in Lassen, Shasta, and Modoc Counties of northern California (Fig. 21C).  emended the type locality of Melania occata to "Sacramento River, California (between American River and mouth)" given that the types were collected during the voyage of the HMS Sulphur which traveled no further upstream than the mouth of the American River. Museum records (e.g., UMMZ 40420, UMMZ 134037) indicate that the species once inhabited the Sacramento River and the lower part of the San Joaquin River watershed to Antioch, California (Henderson 1935a: 96), but was extirpated in the 19 th century from the lower Sacramento River system owing to the effects of mining, pollution, and impoundment , 2010Furnish 2007). Only three river miles of the Upper Sacramento River were unaffected by the Cantara chemical spill in 1991, but surveys found it already extirpated there as well; there are no museum records from the Upper Sacramento River since at least 1940 ).

Remarks
The type locality of G. a. var. siskiyouensis was indicated to be the headwaters of the Fall River in southeastern Siskiyou County. However, the Fall River is considered to originate at Thousand Springs in northeastern Shasta County. Bear Creek is a major tributary that joins the river near its origin and flows from southeastern Siskiyou County and may have been the source of the type material. Attempts to collect from Bear Creek by the authors were unsuccessful. The type locality of G. a. pittensis at the confluence of the Fall and Pit Rivers is now impounded, heavily polluted, and eutrophic from agricultural runoff and Juga no longer occurs there.

Distribution
The main part of the distribution of Juga occata lies in southern Pit River drainages in Shasta and Lassen Counties where it overlaps with J. douglasi sp. nov., although individuals of the two species are rarely found in syntopy; only three lots with mixtures of the two were found in the USNM collections, and one species is always numerically dominant [USNM 1111864, USNM 1665623 (ex USNM 1111864); USNM 892372, USNM 1665624 (ex USNM 892372); USNM 892373, USNM 1665622 (ex USNM 892373)]. In contrast to J. douglasi, juveniles of occata are lirate, although not always prominently so, and erosion frequently obscures details of the spire; the spire angle in occata is also generally broader and the suture less impressed (Fig. 25X-D'). Sequenced specimens from two sites sampled by Campbell  et al. (2016) and lirate museum specimens collected nearby (UF 520309, UF 520312, CASIZ 165958, CASIZ 166008, CASIZ 166015) confirm that the current range of occata extends as far south as central western Lassen County. If reliable, one historical lot (ANSP 73521) collected in the late 19 th century from Battle Creek along the southern border of Shasta County indicates that the well-sculptured form also extended into smaller tributaries of the Sacramento River. Most historical lots from the lower Sacramento and San Joaquin Rivers, including the types, are poorly localized specimens of the typical, sculptured, large river form. We could find no evidence of early teleoconchs with the characteristic lirae south of the Pit watershed and, thus, records in the Sierra Nevada are tentatively hypothesized to represent Juga douglasi. However, given the range of morphological variation seen in species of Juga, it is possible that populations from the Sierra Nevada represent mixtures of J. occata and J. douglasi, or an as yet undescribed form.

Common name
The common name for this species is the Topaz Juga , erroneously referred to as the Scalloped Juga by Turgeon et al. (1988Turgeon et al. ( , 1998, which was followed by  and Johnson et al. (2013) (see J. acutifilosa, above). A composite species comprised of J. acutifilosa and J. occata as circumscribed herein has been referred to as the Willow Creek Juga (= Juga (Calibasis) n. sp. 1; ).

The fossil record of Juga H. & A. Adams, 1854
Given that names of fossil taxa described from late Pliocene to Pleistocene (Blancan) age might be applicable to Recent species, several observations on these forms are relevant here. Taylor (1966) was the first to revise the fossil taxa attributed to Juga in the Blancan fauna of North America and recognized J. kettlemanensis kettlemanensis (Arnold, 1909), J. k. woodringi (Pilsbry, 1934), J. chrysopylica Taylor, 1966 and J. arnoldiana (Pilsbry, 1934). At the same time, he established the subgeneric classification of Juga based on the ontogeny of teleoconch sculpture with J. chrysopylica as the type of the extinct subgenus Idabasis. Given the implications of the molecular analyses for the subgeneric classification of extant forms (Strong & Whelan 2019), we infer that subgeneric distinctions based on shell sculpture similarly would not be meaningful for the fossils and have here synonymized Idabasis with Juga. Likewise, we consider recognition of subspecies of J. kettlemanensis (e.g., Pilsbry 1934;Taylor 1966; to be unjustified and recommend synonymizing J. k. woodringi with kettlemanensis. Furthermore, we consider none of these nominal fossil species to be conspecific with any in the modern fauna and thus none of these names should be considered as available for one of the Recent species, including those described here as new. In addition to the four fossil species treated by Taylor (1966),  included J. sculptilis (Meek, 1870) and J. subsculptilis (Meek, 1870) as valid species of Blancan age. However, we follow Taylor (1975b, and references therein) who indicated the species not to be of Blancan age but of early or middle Pliocene age, and who considered J. sculptilis to be a synonym of J. subsculptilis.

Nomina nuda and taxa excluded from Juga H. & A. Adams, 1854
Frest & Johannes (2010: table 6) provided a list of names that are "invalid" or have been incorrectly used in combination with the genus-group name Juga. However, they included several names that have not been used in combination with Juga but were simply described from the West Coast of North America in genera that are now considered to be pleurocerids or viviparids. They also summarized incorrect subsequent spellings, lapsus calami, incorrect author attributions, and nomina nuda; while some are synonyms and hence not taxonomically valid, nomina nuda and incorrect subsequent spellings are not available names and hence cannot be taxonomically invalid. To their list we make the following additions and corrections. proliferation of species-group names and recognized OTUs. For example, one of the species described here as new, Juga canella sp. nov., represents a mixture of at least five morphotypes each occupying a different drainage and previously hypothesized to each represent a distinct and undescribed new species (see chresonymy, above). This pattern also explains the challenge in allocating some poorly localized historical specimens, including types, to recognized species. The dense population sampling and sequencing effort of Strong & Whelan (2019) has alleviated this to some extent; however, surveys have failed to locate the source population(s) of the distinctive type material of bulbosa, which may no longer be extant (Strong & Frest 2007;. By the same token, most species, even those whose morphological range intergrades with other species, include distinctive forms that cannot be confused for any other species (e.g., the low spired, broadly conical morph of newberryi, the "bairdiana" morph of bulbosa, and the heavily sculptured, large river morphs of occata and plicifera). However, the sequenced populations of J. caerulea sp. nov. and J. douglasi sp. nov. are rather simple, smooth, dark, lightly constructed, mostly without distinguishing sculpture; J. acutifilosa, bulbosa, canella, and nigrina all possess forms that have converged on this basic morphotype. In the absence of precise locality information or sequence data, many of these morphs cannot be reliably identified to species.
Given this complicated morphological landscape, it is unsurprising that the two most wide-ranging and morphologically variable species, J. plicifera and J. nigrina, are the most taxonomically complex. As circumscribed herein, they overlap in color, banding, and strength and persistence of spiral and axial sculpture, and as such, these two species and their many synonyms have been widely confused and variably interpreted. The molecular analyses of Strong & Whelan (2019) confirmed that the two species have allopatric distributions, with plicifera occurring in the Willamette River drainage and northwards, and nigrina occurring in the Umpqua River drainage and southwards. The break in their distribution coincides with the boundary between the Klamath and Oregonian biogeographic provinces for land and freshwater mollusks (sensu Frest & Johannes 2000a, 2000b at the southern end of the Willamette River drainage and adjoining Pacific drainages. Despite the lack of discrete, diagnosable differences between the two, plications tend to be more strongly developed in plicifera and can extend farther down the shell than in nigrina, sometimes reaching the body whorl. The shell of plicifera is typically more heavily constructed than nigrina, but large river forms of both species are thicker and more sculptured than those found in small creeks and streams. Larger, more robust specimens of nigrina with more prominent sculpture are usually found in larger rivers in the northern part of the range, while specimens from the southern part of the range are more lightly constructed, often lighter in color, and typically lack plications ( Fig. 23Y-D').
While the molecular analyses of Strong & Whelan (2019) clarified the diversity of species of Juga, mitochondrial and nuclear gene trees did not agree on the relationships between them. Additional sequencing effort with more nuclear loci is needed to resolve internal nodes and to clarify the identities of the Sierra Nevada populations. Population genomics could better illuminate intraspecific relationships among shell morphs and patterns of gene flow across the landscape. Surveys are also needed to clarify the status of isolated observation records in the eastern Columbia Gorge. Furthermore, many populations have not been revisited in years if not decades and may be no longer extant. Efforts by the authors to recollect some populations that had been sampled by Frest & Johannes were unsuccessful, evidently the victim of drought, trampling from grazing, eutrophication, and other human-mediated impacts.

Conservation
A reliable and accurate taxonomic framework is essential for meaningful interpretations and comparisons of past, present, and future anatomical, physiological, ecological, biogeographical, and life history studies, which are all needed to devise effective conservation management plans. Both locally and globally, freshwater mollusks are facing increasing threats from human-mediated impacts, including climate change, and rank among the most threatened animals on Earth with the highest rates of modern extinction . However, understanding of their biodiversity continues to be plagued by significant knowledge shortfalls (Lydeard et al. 2004;Strong et al. 2008;Johnson et al. 2013;Böhm et al. 2021;Lopes-Lima et al. 2021). Knowledge shortfalls are now even more pronounced for Juga, as the new systematic framework has redrawn species boundaries to cut across almost all species as previously defined. The implications are that much of the conventional knowledge of Juga species, what little we do know, in terms of their life histories, distributions, population size and structure, ecological tolerances, and habitat preferences will require reassessment. Basic demographic, life history, and ecological information is essential for updating the conservation status of these species.
Despite the need to generate conservation-relevant data on the species recognized here, some generalizations are possible. Juga species are found predominantly in groundwater-dependent habitats including springs, spring runs, and spring-fed creeks. These fragile ecosystems face increasing threats from climate change as temperatures increase, precipitation declines, and droughts and wildfires become more severe (Johannes 2015). These threats are compounding other human-mediated impacts from pollution (urban runoff, agriculture), eutrophication, recreation, water diversions and groundwater extraction (irrigation and livestock), dam construction, sedimentation, and habitat fragmentation and loss. Many populations have declined in size, and for some species (e.g., J. occata) the range has contracted markedly Duncan 2005;Furnish 2007;Blackburn et al. 2021). However, some entities thought to require federal protection are now known to be part of much wider ranging species (e.g., the undescribed Basalt Juga), which may make management actions less necessary. On the other hand, one newly described species, J. caerulea sp. nov., has an extremely restricted current range and may warrant immediate protection.