Juga occata ( Hinds, 1844 )

Strong, Ellen E., Garner, Jeffrey T., Johnson, Paul D. & Whelan, Nathan V., 2022, A systematic revision of the genus Juga from fresh waters of the Pacific Northwest, USA (Cerithioidea, Semisulcospiridae), European Journal of Taxonomy 848, pp. 1-97 : 74-80

Juga occata ( Hinds, 1844)

Figs 25–26

Melania occata Hinds, 1844: 9 .

Goniobasis acutifilosa var. siskiyouensis Pilsbry, 1899: 65–66 .

Goniobasis acutifilosa pittensis Henderson, 1935a: 134 , pl. 4 fig. 11.

Melania occata – Hinds 1845: 56–57, pl. 15 fig. 5.

Melania shastaensis – Reeve 1860: unpaginated, species 318, pl. 44 fig. 318.

Goniobasis acutifilosa pittensis – Henderson 1936b, pl. 2 fig. 11.

Juga (Calibasis) occata – Burch & Tottenham 1980: 152, fig. 451. — Burch 1982: 41, fig. 451; 1989: 152, fig. 451. — Frest & Johannes 1993: 61; 1995b: 38; 2010: 10, 44, fig. 2e. — Furnish 2007: 16, fig. 6, above right. — Campbell et al. 2016: 160.

Juga (Calibasis) acutifilosa siskiyouensis – Burch & Tottenham 1980: 152. — Burch 1982: 41; 1989: 152.

Juga (Calibasis) acutifilosa pittensis – Burch & Tottenham 1980: 152. — Burch 1982: 41; 1989: 152.

Juga occata – Turgeon et al. 1988: 65; 1998: 67. — Johannes & Clark 2016: 24. — Johnson et al. 2013: 282. — Strong & Whelan 2019: 89, fig. 4m –q.

Juga (Calibasis) acutifilosa – Frest & Johannes 1993: 61 (in part); 1995 b: 37 (in part); 2000a: 283 (in part); 2005: 160 (in part); 2010: 9, 22 (in part). — Furnish 2007: 14, fig. 6, above left.

Juga (Calibasis) n. sp. 1 – Frest & Johannes 1995b: 38 (in part).

Juga (Calibasis) OTU 3 – Campbell et al. 2016: 160.

Juga (Calibasis) OTU 4 – Campbell et al. 2016: 160.

Juga (Calibasis) OTU 5 – Campbell et al. 2016: 160.

Material examined

Melania occata Hinds, 1844 USA • 1 spm (possible syntype, Fig. 25A ); “ River Sacramento , California ”; R.B. Hinds leg.; NHMUK 4.9.23.34 .

Lectotype of Goniobasis acutifilosa var. siskiyouensis Pilsbry, 1899 (designated by Baker 1964: 187) USA • “ Headwaters of Fall River , S.-E. [southeast] Siskiyou Co. ”; R.C. McGregor leg.; ANSP 73508 .

Paralectotypes of Goniobasis acutifilosa var. siskiyouensis Pilsbry, 1899 ( Fig. 25B ) USA • 90 spms; same collection data as for lectotype; ANSP 466291 (ex ANSP 73508 ).

Holotype of Goniobasis acutifilosa pittensis Henderson, 1935 ( Fig. 25C ) USA • “ Fall River Mills , on Pitt [sic, Pit] River, California ”; Ellsworth Bethel leg.; UCM 12080a.

Paratypes of Goniobasis acutifilosa pittensis Henderson, 1935 USA • 2 spms; same collection data as for holotype; UCM 12080b.

Other material examined 48 lots, 898 specimens, of which 21 were sequenced.

USA – California • 5 spms; Lassen Co., Davis Creek, Lassen NF, above FS22; 40.8325, -121.1183; 1 Sep. 2007; T. Grace leg.; UF 520312 • 54 spms; Lassen Co., Lassen Natl Forest, Davis Creek , on FS Rd 22; [40.8375, -121.1183]; 5 Jun. 2001; USFS Lassen Natl Forest Mollusk Survey 2001; CASIZ 166015 • 39 spms; Lassen Co., Lassen Natl Forest, Davis Creek , on FS Rd 22 [= FS Rd 35N05]; [40.8375, -121.1183]; 5 Jun. 2001; USFS Lassen Natl Forest Mollusk Survey 2001; CASIZ 165958 • 199 spms; Lassen Co., Lassen Natl Forest, Russell Dairy Spring , on 35N85 [= FS Rd 35N05]; [40.8277, -121.0281]; 2001; USFS Lassen Natl Forest Mollusk Survey 2001; CASIZ 166008 • 35 spms; Lassen Co., Russell Dairy Spring Run, Lassen NF, FS22 and 34N2, S side of road; 40.8253, -121.0268; 1 Sep. 2007; T. Grace leg.; UF 520309 • 12 spms; Modoc Co., Goose Lake ; [41.9067, -120.3652]; 26 Sep. 1979; CASIZ 85267 • 2 spms; Modoc Co., Modoc Natl Forest, W end of Upper Rush Creek Campground , 3.2 km N of Lower Rush Creek Campground; [41.3015, -120.8461]; 8 Oct. 2007; T. Grace leg.; small spring run, among water cress and on rocks and twigs; UF 548146 • 1 spm; Sacramento Co., Sacramento ; [38.5833, -121.5064]; Wetherby leg.; USNM 118914 • 2 spms; Shasta Co., Battle Creek , S boundary of county; [40.3921, -122.1787]; 1898; R.C. McGregor leg.; ANSP 73521 • 49 spms; Shasta Co., Baum Lake ; 40.9345, -121.5485; 10 Sep. 2015; E.E. Strong and P. Bouchet leg.; USNM 1413151 • 1 spm; same collection data as for preceding; GenBank: MK472482 , MK464849 , MK480916 ; USNM 1413146 • 1 spm; same collection data as for preceding; GenBank: MK472483 , MK464850 , MK480917 ; USNM 1413147 • 1 spm; same collection data as for preceding; GenBank: MK472484 , MK464851 , MK480918 ; USNM 1413148 • 1 spm; same collection data as for preceding; GenBank: MK472485 , MK464852 , MK480919 ; USNM 1413149 • 1 spm; same collection data as for preceding; GenBank: MK472486 , MK464853 , MK480920 ; USNM 1413150 • 34 spms; Shasta Co., Fall River at Spinner Fall Lodge ; 41.0972, -121.5491; 11 Sep. 2015; E.E. Strong and P. Bouchet leg.; USNM 1413084 • 1 spm; same collection data as for preceding; GenBank: MK472471 , MK464838 , MK480906 ; USNM 1413079 • 1 spm; same collection data as for preceding; GenBank: MK472472 , MK464839 , MK480907 ; USNM 1413080 • 1 spm; same collection data as for preceding; GenBank: MK472473 , MK464840 , MK480908 ; USNM 1413081 • 1 spm; same collection data as for preceding; GenBank: MK472474 , MK464841 , MK480909 ; USNM 1413082 • 1 spm; same collection data as for preceding; GenBank: MK472475 , MK464842 , MK480910 ; USNM 1413083 • 29 spms; Shasta Co., Hat Creek Park, Hat Creek, E of Burney at highway bridge; [40.9767, -121.5565]; 16 May 1978; J. Landye leg.; sand and emergent vegetation; USNM 892368 • 50 spms; Shasta Co., Hat Creek Park, Hat Creek, E of Burney at highway crossing; [40.9767, -121.5565]; 16 May 1978; J. Landye leg.; on sand and vegetation; USNM 892375 • 9 spms; Shasta Co., near border of Modoc County, N of McArthur , Big Lake , Crystal Springs ; [41.1118, -121.4494]; 16 Jul. 1980; CASIZ 85274 • 55 spms; Shasta Co., Pit River at U.S. Hwy 299; 40.9807, -121.5473; 11 Sep. 2015; E.E. Strong and P. Bouchet leg.; USNM 1413091 • 1 spm; same collection data as for preceding; GenBank: MK472476 , MK464843 , MK480911 ; USNM 1413085 • 1 spm; same collection data as for preceding; GenBank: MK472477 , MK464844 , MK480912 ; USNM 1413086 • 1 spm; same collection data as for preceding; GenBank: MK472478 , MK464845 ; USNM 1413087 • 1 spm; same collection data as for preceding; GenBank: MK472479 , MK464846 , MK480913 ; USNM 1413088 • 1 spm; same collection data as for preceding; GenBank: MK472480 , MK464847 , MK480914 ; USNM 1413089 • 1 spm; same collection data as for preceding; GenBank: MK472481 , MK464848 , MK480915 ; USNM 1413090 • 57 spms; Shasta Co., Pit River, above Lake Britton and upstream from Hat Creek ; [40.9805, -121.5476]; 16 May 1978; J. Landye leg.; in pockets along rocky shore in eddies; USNM 892363 • 16 spms; Shasta Co., Rainbow Springs, at headwaters of Fall Mill Creek on Lazy S Ranch adjacent to Thousand Springs Ranch ; [41.1111, -121.5511]; 16 May 1978; J. Landye leg.; USNM 892373 • 75 spms; Shasta Co., Rainbow Springs, in headspring on Lazy S Ranch in Thousand Springs Area ; [41.1111, -121.5511]; 16 May 1978; J. Landye leg.; on rocks; USNM 892380 • 15 spms; Shasta Co., S side of Hwy 299, Pit River , Lion’s Club picnic area, W of Pit River camping grounds; 40.9866, -121.513; 1 Sep. 2007; T. Grace leg.; USNM 1111864 • 2 spms; Shasta Co., S side of Pit River, water source spring at Pacific Gas and Electric plant; [40.9896, -121.5021]; 16 May 1978; J. Landye leg.; USNM 892372 • 58 spms; Shasta Co., S side of Pit River, water source spring at Pacific Gas and Electric Plant #1; [40.9896, -121.5021]; 16 May 1978; J. Landye leg.; USNM 892365 • 46 spms; Shasta Co., Spring Creek at Spring Creek Rd ; 41.1018, -121.5189; 11 Sep. 2015; E.E. Strong and P. Bouchet leg.; USNM 1413164 • 1 spm; same collection data as for preceding; GenBank: MK472487 , MK464854 , MK480921 ; USNM 1413159 • 1 spm; same collection data as for preceding; GenBank: MK472488 , MK464855 ; USNM 1413160 • 1 spm; same collection data as for preceding; GenBank: MK472489 , MK464856 , MK480922 ; USNM 1413161 • 1 spm; same collection data as for preceding; GenBank: MK472490 , MK464857 , MK480923 ; USNM 1413162 • 1 spm; same collection data as for preceding; GenBank: MK472491 , MK464858 ; USNM 1413163 • 18 spms; Sacramento River ; Trask leg.; USNM 119157 • 2 spms; same collection data as for preceding; U.S. Exploring Expedition; USNM 16251 • 7 spms; Upper Sacramento ; USNM 58982 • 3 spms; Sacramento River , headwaters [sic, likely mislocalized]; USNM 56463 . – Oregon • 3 spms; Clatsop Co., Astoria [sic, mislocalized]; White leg.; USNM 126074 .

Description

SHELL. Thin to moderately thick, large, reaching ~ 2.75 cm in length; turriform, narrowly or broadly conical to cylindrical in shape, spire height moderate to tall ( Fig. 25 ). 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, 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 ).

Remarks

Taylor (1981) 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 ( Taylor 1981; Frest & Johannes 1993, 2010; Furnish 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 ( Frest & Johannes 1993).

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.

Juga occata has been considered a robust, heavily sculptured, large river form ( Fig. 25D–F ) ( Burch & Tottenham 1980; Taylor 1981; Burch 1982, 1989; Frest & Johannes 1993, 2010), but molecular analyses indicate that this form is conspecific with less heavily sculptured populations that occur in lakes and spring-fed creeks ( Strong & Whelan 2019). This includes near topotypic specimens ( Fig. 25H–J ) of Goniobasis acutifilosa var. siskiyouensis and G. a. pittensis. The classifications of Burch & Tottenham (1980) and Burch (1982, 1989) recognized these two subspecies as valid, but recent classifications ( Turgeon et al. 1988, 1998; Johnson et al. 2013) did not consider the rank of subspecies. Frest & Johannes (2010) followed Taylor (1981) in synonymizing siskiyouensis with J. acutifilosa , and pittensis with J. occata , while Campbell et al. (2016: supp. file 1) synonymized both with occata .

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 ( Frest & Johannes 1993) , erroneously referred to as the Scalloped Juga by Turgeon et al. (1988, 1998), which was followed by Frest & Johannes (2010) 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; Frest & Johannes 1995b).

Figures

Fig. 25 (next page). Shell morphology of Juga occata (Hinds, 1844). A–C. Primary type material. D–J. Sequenced vouchers. A. Melania occata Hinds, 1844. Possible syntype, USNM 4.9.23.34. B. Goniobasis acutifilosa var. siskiyouensis Pilsbry, 1899. Lectotype, ANSP 73508. C. Goniobasis acutifilosa pittensis Henderson, 1935. Holotype, UCM 12080a. D. USNM 1413088. E. USNM 1413085. F. USNM 1413086. G. USNM 1413146. H–J. Near topotypic (Goniobasis acutifilosa var. siskiyouensis Pilsbry, 1899; Goniobasis acutifilosa pittensis Henderson, 1935). H. USNM 1413159. I. USNM 1413082. J. USNM 1413079. K. CASIZ 85267. L. UF 548146. M–N. Paralectotype, ANSP 466291 (ex ANSP 73508). O–Q. USNM 892373. R. USNM 892363. S–T. CASIZ 85274. U. USNM 892368.V. CASIZ 165958. W. ANSP 73521. X. USNM 892380. Y. USNM 892363. Z. USNM 1111864. A’. USNM 892372. B’. USNM 892368. C’. USNM 892375. D’. CASIZ 166015. Scale bar: 1 cm.

Fig. 26. Radular morphology of Juga occata (Hinds, 1844) (USNM 1413085). A. View of the anterior radular ribbon. B. Detail of cutting edge of rachidian and lateral teeth. C. Detail of lateral teeth cusps. D. Detail of rachidian cusps. E. Inner and outer marginal teeth. F. Detail of inner and outer marginal teeth cusps. Scale bars: A = 300 µm; B, E = 100 µm; C–D, F = 50 µm.

Fig. 21. Distribution maps. A. Juga newberryi (I. Lea, 1860). B. Juga nigrina (I. Lea, 1856). C. Juga occata (Hinds, 1844). Red stars, type localities; black dots, sequenced specimens; gray dots, unsequenced museum material. Abbreviations: CA = California; NV = Nevada; OR = Oregon; WA = Washington.