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Despite the important roles of freshwater gastropods in aquatic ecosystems, the taxonomic status of many taxa is unclear, which is compounded by a lack of information on species population genetic structuring, distribution, and dispersal patterns. The objective of this study was to address the biogeography of the freshwater snail Planorbella trivolvis (Gastropoda: Planorbidae) in the western United States. We amplified two genetic markers (16S, COI) from individuals belonging to western USA populations and downloaded genetic data from GenBank. We utilized minimum spanning networks to assess the genetic patterns and performed Analysis of Molecular Variance and linear regression analyses to determine how geographic distance and watershed identity contributed to the observed genetic structuring. For both markers, we found that the majority of genetic variation was associated within and among populations, rather than among watersheds. Correspondingly, there was no significant effect of geographic distance on genetic distance, suggesting that long-distance dispersal was promoting gene flow between populations. The genetic similarity could reflect avian-mediated dispersal of snails along the Pacific Flyway, a major waterfowl migratory corridor. Further analysis of the population structuring across North America revealed East-West genetic structuring, suggesting that across longitudinal gradients P. trivolvis experiences significant genetic isolation.

Parasite infections often lead to dramatically different outcomes among host species. Although an emerging body of ecoimmunological research proposes that hosts experience a fundamental trade-off between pathogen defences and life-history activities, this line of inquiry has rarely been extended to the most essential outcomes of host-pathogen interactions: namely, infection and disease pathology. Using a comparative experimental approach involving 13 amphibian host species and a virulent parasite, we test the hypothesis that pace-of-life predicts parasite infection and host pathology. Trematode exposure increased mortality and malformations in nine host species. After accounting for evolutionary history, species that developed quickly and metamorphosed smaller (fast-species) were particularly prone to infection and pathology. This pattern likely resulted from both weaker host defences and greater adaptation by parasites to infect common hosts. Broader integration between life history theory and disease ecology can aid in identifying both reservoir hosts and species at risk of disease-driven declines.

Summary 1. An emerging framework in animal disease ecology seeks to ‘decompose’ a host’s response to disease into resistance, or its ability to resist infection following exposure, and tolerance, or its ability to limit the damage associated with infection. How these processes vary over the life history of a host, however, and whether developmental changes in resistance and tolerance account for ‘critical windows’ of disease vulnerability remain open questions. 2. Critical developmental windows are particularly important for infections that alter host development. Recently, increased observations of amphibians with severe limb malformations have stimulated debate over the causes responsible and whether malformation types can be used to infer the agent responsible. The trematode parasite Ribeiroia ondatrae, for example, is often implicated in accounts of extra-legged frogs, but is believed to be unimportant in explaining missing legged animals. Here, we test the influence of host developmental stage, from eggs to post-metamorphosis, on the risk of mortality and the types of malformations produced in Pacific chorus frogs (Pseudacris regilla) following exposure to trematode infection. 3. Consistent with a critical window of vulnerability, host mortality and malformations were greatest among animals exposed during pre-limb and early limb development (15–90%) and decreased to

minima, egg mass, oviposition More than half of the known remaining populations of the Oregon Spotted Frog (Rana pretiosa) are at elevations .1200 m along the Cascade Range and its eastern flank in Oregon (Pearl and Hayes 2005). Rana pretiosa in this region typically breed soon after thaw and often lay eggs in water ,20 cm deep (Pearl and others 2009). Egg masses in shallow microhabitats experience broad temperature fluctuations, and ice formation on the surface is common (Bull and Shepherd 2003). At .20 oviposition sites around Sunriver in central Oregon (elevation 1270 m), we have observed high survival of R. pretiosa embryos after exposure to subfreezing air temperatures and ice cover for up to several days. These observations and the characteristics of oviposition sites across much of the species’ range along the Cascade Range suggest that R. pretiosa eggs in this region may be more tolerant of low temperatures than previously reported. Information on thermal limits of R. pretiosa embryos derives from studies of 1 population in the Fraser River Valley of southwestern British Columbia. The low elevation of this site (approximately 50 m above sea level) and its proximity to the Strait of Georgia and Pacific Ocean make its climate more moderate than much of the extant range of R. pretiosa. Licht (1971) reported a lethal minimum, the temperature at which egg survival is ,50%, near 66C for eggs from that site at a range of stable temperature treatments in the laboratory. A subset of embryos survived lower temperatures for up to 8 h, after which trials were terminated (Licht 1971), but data were not presented on presence or timing of develop

While many predators completely consume their prey, others feed only on blood or tissue without killing the prey, sometimes causing ecologically significant levels of injury. We investigated the importance of sublethal predator attacks in driving an emerging issue of conservation importance: missing-limb deformities in amphibians. We combined long term field data and manipulative experiments to evaluate the role of sublethal predation in causing abnormalities in two regions of central Oregon, USA. Since 1988, western toads (Bufo boreas) in Lake Aspen have exhibited abnormalities dominated by partially missing limbs and digits at annual frequencies from < 1% to 35%. On Broken Top volcano, we found comparable types and frequencies of abnormalities in Cascades frogs (Rana cascadae). Field sampling and observational data implicated two aquatic predators in these abnormality phenomena: introduced sticklebacks (Gasterosteus aculeatus) at Lake Aspen and corduliid dragonfly larvae (Somatochlora albicinctd) at Broken Top. In experiments, these predators produced limb abnormalities identical to those observed in the respective regions. At Lake Aspen, in situ predator exclosures effectively eliminated abnormalities in toads, while comparisons among years with low and high stickleback abundance and between wetlands with and without sticklebacks reinforced the link between fish and amphibian abnormalities. Neither trematode parasite infection nor pesticide contamination could explain observed abnormalities. Our results suggest that predators are an important explanation for missing-limb abnormalities and highlight the ecological significance of sublethal predation in nature.

We used five years of recapture data and Bayesian estimation to assess seasonal survival, movement, and growth of Oregon Spotted Frogs (Rana pretiosa) relocated into created ponds at Dilman Meadow in Oregon, USA. We evaluate hypotheses specific to the relocation and elucidate aspects of R. pretiosa life history that are poorly known. The odds of survival of relocated individuals during the first year following relocation were 0.36 times the survival odds of relocated and non-relocated frogs after one year since the relocation. Survival rate was higher for large frogs. After accounting for frog size, we found little variation in survival between ponds at Dilman Meadow. Survival was lowest for males during the breeding/post-breeding redistribution period, suggesting a high cost of breeding for males. The highest survival rates occurred during winter for both genders, and one small spring was used heavily during winter but was used rarely during the rest of the year. Individual growth was higher in ...

Chytridiomycosis (infection by the fungus Batrachochytrium dendrobatidis) has been associated with amphibian declines in at least four continents. We report results of disease screens from 210 pond-breeding amphibians from 37 field sites in Oregon and Washington. We detected B. dendrobatidis on 28% of sampled amphibians, and we found ≥ 1 detection of B. dendrobatidis from 43% of sites. Four of seven species tested positive for B. dendrobatidis, including the Northern Red-Legged Frog (Rana aurora), Columbia Spotted Frog (Rana luteiventris), and Oregon Spotted Frog (Rana pretiosa). We also detected B. dendrobatidis in nonnative American Bullfrogs (Rana catesbeiana) from six sites in western and central Oregon. Our study and other recently published findings suggest that B. dendrobatidis has few geographic and host taxa limitations among North American anurans. Further research on virulence, transmissibility, persistence, and interactions with other stressors is needed to assess the potential impact...

Introduced American bullfrogs (Rana catesbeiana) come in contact with native amphibians on four continents and are well established in lowlands of western North America. To date, research on the effects of introduced bullfrogs on native frogs has focused on competition and predation, and is based largely on larval interactions. We present observations of interspecific amplexus between bullfrogs and two native ranid frogs (R. aurora and R. pretiosa) from six sites across the Pacific Northwest that imply that this interaction is more widespread than currently recognized. Our observations indicate that R. catesbeiana juveniles and subadults in this region are of appropriate size to elicit marked amplectic responses from males of both native species. Our literature review suggests that greater opportunity may exist for pairings between R. catesbeiana and native R. aurora or R. pretiosa than among syntopic native ranids in western North America. We hypothesize that interspecific amplexus with introduc...

Parasites and pathogens can influence the survivorship, behavior, and very structure of their host species. For example, experimental studies have shown that trematode parasites can cause high frequencies of severe limb malformations in amphibians. In a broad-scale field survey covering parts of California, Oregon, Washington, Idaho, and Montana, we examined relationships between the frequency and types of morphological abnormalities in amphibians and the abundance of trematode parasite infection, pH, con- centrations of 61 pesticides, and levels of orthophosphate and total nitrate. We recorded severe malformations at frequencies ranging from 1% to 90% in nine amphibian species from 53 aquatic systems. Infection of larvae by the trematode Ribeiroia ondatrae was associated with, and functionally related to, higher frequencies of amphibian limb malfor- mations than found in uninfected populations (#5%). Parasites were concentrated around the basal tissue of hind limbs in infected anurans, and malformations associated with infection included skin webbings, supernumerary limbs and digits, and missing or mal- formed hind limbs. In the absence of Ribeiroia, amphibian populations exhibited low (0- 5%) frequencies of abnormalities involving missing digits or distal portions of a hind limb. Species were affected differentially by the parasite, and Ambystoma macrodactylum , Hyla regilla, Rana aurora, R. luteiventris, and Taricha torosa typically exhibited the highest frequencies of abnormalities. None of the water-quality variables measured was associated with malformed amphibians, but aquatic snail hosts (Planorbella spp.) were significant predictors of the presence and abundance of Ribeiroia infection. Morphological comparisons of adult specimens of Ribeiroia collected from different sites and raised in experimental definitive hosts suggested that all samples represented the same species— R. ondatrae. These field results, coupled with experimental research on the effects of Ribeiroia on amphibians, demonstrate that Ribeiroia infection is an important and widespread cause of amphibian limb malformations in the western United States. The relevance of trematode infection to declines of amphibian populations and the influence of habitat modification on the pathology and life cycle of Ribeiroia are emphasized as areas requiring further research.

From 2001 to 2005, we studied the demography and seasonal movement of Oregon spotted frogs (Rana pretiosa) translocated into created ponds in Dilman Meadow in central Oregon. Our objectives were to inform future monitoring and management at the site, and to elucidate poorly known aspects of the species’ population ecology. Movement rates revealed complementary use of sites seasonally, with one small spring being preferred during winter that was rarely used during the rest of the year. Growth rates were significantly higher in ponds that were not used for breeding, and larger size resulted in significantly higher survival. When variation in survival by size was accounted for there was little variation among ponds in survival. Seasonal estimates of survival were lowest for males during the breeding/post-breeding redistribution period, suggesting a high cost of breeding for males. Overwintering survival for both genders was relatively high. Our study supports others in suggesting Oregon spotted frogs are specific in their overwintering habitat requirements, and that predator-free springs may be of particular value. We suggest that any future monitoring include measures of the rate of pond succession. Demographic monitoring should include metrics of both frog reproduction and survival: counts of egg masses at all ponds during spring, and capture-recapture study of survival in mid and late summer when capture rates are highest. Additional study of early life stages would be particularly useful to broaden our understanding of the species’ ecology. Specifically, adding intensive capture and marking effort after larval transformation in fall would enable a full understanding of the annual life cycle. Complete study of the annual life cycle is needed to isolate the life stages and mechanisms through which Oregon spotted frogs are affected by stressors such as nonnative predators. Dilman Meadow, which lacks many hypothesized stressors, is an important reference for isolating the life stages most responsive to management elsewhere in the species’ range. Oregon Spotted Frog (Rana pretiosa) Movement and Demography at Dilman Meadow: Implications for Future Monitoring By Nathan D. Chelgren, Christopher A. Pearl, Jay Bowerman, and Michael J. Adams

A new species of ectoparasitic glossiphoniid leech was found feeding on frogs in the Nature Center Pond and elsewhere in Deschutes County, Oregon. The new species of Placobdella resembles the southern alligator leech, Placobdella multilineata Moore, 1953, notwithstanding their vast geographic separation in North America. The new species is readily distinguished by possessing subdivided annuli, by its papillation and pigmentation patterns as well as by the arrangement of ovarian tissues. There is strong evidence of nocturnality and of the potential for parasitizing humans.

Helobdella bowermani n. sp. Figures 1���3 Material examined. Holotype (USNM 1213041) Ball Bay (42 �� 24 ��� 21 ���N 122 �� 01��� 01���W) Upper Klamath Lake, Klamath County, Oregon on 30 May 2012. Paratypes (USNM 1213042) 8 specimens mid-trench (42 �� 23 ��� 05���N 121 �� 55 ��� 38 ���W), 6 November 2008, 4 whole mount slides (USNM 1225776���1225779); USNM 1213043 3 specimens Ball Bay (42 �� 24 ��� 21 ���N 122 �� 01��� 01���W) on 30 May 2012, 2 whole mount slides (USNM 1225780���1225781); USNM 1213044 9 specimens midtrench (42 �� 23 ��� 05���N 121 �� 55 ��� 38 ���W), 18 June 2008; USNM 1213045 2 specimens mid-trench (42 �� 23 ��� 05���N 121 �� 55 ��� 38 ���W), May 2008; USNM 1213046 8 specimens mid-north (42 �� 26 ��� 22 ���N 122 �� 00��� 40 ��� W), 30 May 2012, 1 whole mount slide (USNM 1225782); USNM 1213047 3 specimens Modoc Rim (42 �� 24 ��� 37 ���N 121 �� 51 ��� 52 ���W), 18 June 2008; YPM IZ 67710 4 specimens mid-trench (42 �� 23 ��� 05���N 121 �� 55 ��� 38 ���W), 18 June 2008; Upper Klamath Lake, Klamath County, Oregon. Description. External morphology. Body lanceolate; length of preserved specimens 5.2���9.7 mm, mean �� SE 7.2 �� 0.2 mm (n= 38), width at widest point 1.7���4.5 mm, mean 3.0 �� 0.1 mm (n= 38). Dorsum pale yellow/buff with scattered chromatophores throughout the dorsal surface (Figs. 1 A���B). Pair of widely separated eye spots and pair of black longitudinal pigment lines extending posteriad from the eye spots for a few annuli. Small oval-shaped nuchal scute (occasionally triangular) on VIII, raised in preserved specimens (Figs. 1 A���B). Dorsal medial row of papillae with papillae on the a 1 (papilla small), a 2 (papilla large) and a 3 (papilla large) annulus (Figs. 1 A���B). Medial dorsal papillae row extends posteriad below the nuchal scute to a couple of annuli anteriad of the anus. Additional row of papillae at the extreme lateral margins on the a 2 (neural) annulus, giving the body a serrated or denticulate appearance (Figs. 1���2). Lateral papillae row begins as 2 papillae below the anus and extends anteriad. Anus located 1 annulus anteriad of the caudal sucker. Caudal sucker small to moderate size (half the diameter of mid-body, 0.7���1.3 mm in diameter, mean �� SE, 1.0 �� 0.0 (n= 38), with few black chromatophores and no papillae. Ventrum without papillae and unpigmented (Fig. 2). Male gonopore on annulus and female gonopore in furrow (1 �� annuli between gonopores). Internal morphology. Digestive system: Proboscis pore at center of anterior sucker. Robust proboscis uniformly cylindrical and in membranous sheath. In the anterior third of body, salivary glands diffusely scattered on either side of the proboscis and salivary ductule bundles attaching at each side of the base of the proboscis (Figs. 3 A���B). Short, simple esophagus. Six pair of short, simple unlobed and unbranched crop ceca with no post ceca and four pair of intestinal ceca with the last pair reduced (Figs. 3 A���B). Rectum robust, pyriform and recurved in some specimens (Figs. 3 A���B). Reproductive system: Male atrium opening into paired falciform to luniform atrial cornuae that extend laterally and anteriorly into ejaculatory ducts without atrial loops (Figs. 3 A���B). Six pair of testisacs (Figs. 3 A���B). Female gonopore simple, opening to pair of simple, tubular ovisacs. Length of ovisacs dependent on the reproductive state of the leech. Taxonomic summary. Type locality. Upper Klamath Lake, Klamath County, Oregon. Type material. Holotype USNM 1213041, Paratypes USNM 1213042���1213048, USNM 1225776���1225782, and YPM IZ 67710. Etymology. Named to honor scientist and naturalist Jay Bowerman of the Sunriver Nature Center, Sunriver, Oregon. DNA analysis. Molecular characterization of 614 nucleotides of CO-I revealed differences of 0.0% to 0.2 % (0���1 nucleotide) among three specimens of Helobdella bowermani n. sp. (GenBank KF 683192 ���KF 683194). Differences of 10.6 % to 10.8 % (65 to 66 nuceotides) were found between H. bowermani n. sp. and a specimen of Helobdella californica (GenBank HQ 686307) collected from San Francisco, California. Comparison of CO-I sequence data of three specimens of H. bowermani n. sp. revealed differences of 12.2 % to 13.7 % (75 to 84 nucleotides) among three specimens of Helobdella atli (GenBank HQ 179850 ���HQ 179852), differences of 12.7 % to 13.2 % (78 to 81 nucleotides) among three specimens of Helobdella simplex (GenBank KF 683195 ���KF 683197), differences of 14.5 % to 14.7 % (89 to 90 nucleotides) among two species of Helobdella modesta from Washington (GenBank HQ 179853 ���HQ 179854), differences of 14.7 % to 14.8 % (90 to 91 nucleotides) from a specimen of H. modesta from Ohio (GenBank AF 329040), and differences of 14.7 % to 14.8 % (90 to 91 nucleotides) from a specimen of Helobdella stagnalis from the United Kingdom (GenBank AF 329041). A neighbor joining tree of Helobdella spp. based on CO-I sequence data is presented in Figure 4. Helobdella bowermani n. sp. formed a clade with H. californica, and a sister clade with Helobdella atli had modest support. The sister clade relationship of Helobdella simplex and Helobdella sorojchi had robust support. Figure legends: atrial cornuae (AC), crop ceca (CC), ejaculatory duct (ED), intestinal ceca (IC), proboscis (Pr), rectum (R), salivary cells (Sc), testisac (T 1 ���T 6). Natural history. Helobdella bowermani n. sp. occurs abundantly in the fine sediment and was collected in the open water benthos with an Ekman grab and a 0.5 mm sieve bucket throughout Upper Klamath Lake. The reproductive period for Helobdella bowermani n. sp. was during spring with specimens brooding eggs and hatchlings in May and June, and a second reproductive period was observed in August and September. Remarks. Three nominal species of Helobdella with a nuchal scute occur in the United States: Helobdella modesta (Verrill 1872), Helobdella californica Kutschera 1988, and Helobdella bowermani n. sp. Whether a fourth species of Helobdella with a nuchal scute, Helobdella stagnalis (Linneaus 1758), occurs in the United States is in doubt. At one time, every specimen of Helobdella with a nuchal scute was identified as H. stagnalis, but differences in genetic distance prompted Siddall et al. (2005) to resurrect Helobdella modesta (Verrill 1872). In a molecular characterization of H. modesta from the type locality (New Haven, Connecticut), Moser et al. (2011) suggested H. stagnalis is a complex of cryptic species and additional species similar to H. stagnalis likely exist in the United States. Although H. bowermani n. sp. has a nuchal scute, its dorsal medial row of papillae and a 2 papillae on the lateral margins easily distinguish it from the non-papillated H. modesta and H. stagnalis. Helobdella californica, which formed a clade with H. bowermani n. sp., exhibited a 10.6 % to 10.8 % difference among COI sequence data. Both nuchal scute species occur in the western United States, but H. californica has a pair of longitudinal stripes, diverticulated crop ceca at the lateral ends and no papillae which differentiate it from H. bowermani n. sp. Helobdella californica is also only known from Golden Gate Park [Stow Lake (type locality), San Francisco Botanical Garden Gunnera Creek and Mallard Lake], San Francisco, California (Kutschera 1988; 2011). Helobdella bowermani n. sp. is morphologically similar to H. atli and H. simplex. All three species have a nuchal scute on VIII and dorsal-medial row of papillae. Comparison of H. bowermani COI sequence data with the other two species, revealed differences of 12.2 % to 13.7 % with H. atli and differences of 12.7 % to 13.2 % with H. simplex. There are also morphological differences between H. bowermani n. sp., H. atli and H. simplex. Helobdella simplex has a pale brownish coloration, a dorsal medial black line, 24 fine longitudinal lines, lateral extensions on every annulus, dorsal medial row of papillae with papillae of the same size on every annulus and it has a nuchal gland, but rarely nuchal scute (Moore 1911; Siddall & Borda 2004). Helobdella atli has a white or yellowish base color without any pigmentation, lateral extensions only on the a 2 and a 3 annuli, dorsal medial row of papillae with papillae only on the a 2 and a 3 annuli and a small triangular scute (Oceguera-Figueroa & Leon-Regagnon 2005). Helobdella bowermani n. sp. is differentiated from H. atli and H. simplex by its pale yellow/buff coloration with scattered chromatophore blotches throughout the dorsal surface, lateral extensions or papillae only on the a 2 annulus, dorsal medial row of papillae with small papilla on a 1 and larger papillae on a 2 and a 3, and a small oval scute (rarely triangular). Helobdella bowermani n. sp. is also ecologically distinct, occurring in the fine sediment of open water benthos of an eutrophic lake. Whereas, H. atli is attached underneath submerged rocks and on plants in a lake (Oceguera- Figueroa & Leon-Regagnon 2005) and H. simplex is attached on submerged substrata and aquatic vegetation in rivers, streams and lakes (Moore 1911; Siddall & Borda 2004; Gullo 1998; 2007; C��sar et al. 2009)., Published as part of Moser, William E., Fend, Steven V., Richardson, Dennis J., Hammond, Charlotte I., Lazo-Wasem, Eric A., Govedich, Fredric R. & Gullo, Bettina S., 2013, A new species of Helobdella (Hirudinida: Glossiphoniidae) from Oregon, USA, pp. 287-294 in Zootaxa 3718 (3) on pages 288-293, DOI: 10.11646/zootaxa.3718.3.5, http://zenodo.org/record/222372