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New Host and Geographic-Distribution Records for Helminth and Arthropod Parasites of the Southern Toad, Anaxyrus terrestris (Anura: Bufonidae), from Florida
Chris T. McAllister, Charles R. Bursey, Matthew B. Connior, Stanley E. Trauth, and Lance A. Durden

Southeastern Naturalist, Volume 14, Issue 4 (2015): 641–649

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Southeastern Naturalist 641 C.T. McAllister, C.R. Bursey, M.B. Connior, S.E. Trauth, and L.A. Durden 22001155 SOUTHEASTERN NATURALIST 1V4o(4l.) :1644,1 N–6o4. 94 New Host and Geographic-Distribution Records for Helminth and Arthropod Parasites of the Southern Toad, Anaxyrus terrestris (Anura: Bufonidae), from Florida Chris T. McAllister1,*, Charles R. Bursey2, Matthew B. Connior3, Stanley E. Trauth4, and Lance A. Durden5 Abstract - We collected 18 Anaxyrus terrestris (Southern Toad) in March and May 2014 and July 2015 from Topsail Hill Preserve State Park, Walton County, FL, and examined them for helminth and arthropod parasites. Fourteen toads (78%) were infected or infested with parasites as follows: 2 (11%) with Megalodiscus temperatus, 1 (6%) with tetrathyridia of Mesocestoides sp., 3 (17%) with Cylindrotaenia americana, 2 (11%) with 3rd-stage larval Physaloptera sp., 9 (50%) with Cosmocercoides variabilis, 10 (55%) with Oswaldocruzia pipiens, and 2 (11%) with larval Hannemania hegeneri chigger mites. We observed multiple infections/infestations of helminths and/or arthropods in 7 (39%) of these hosts. Herein, we report 5 new host and 2 new geographic-distribution records. Introduction Anaxyrus terrestris (Bonnaterre) (Southern Toad) is a common toad that has highly pronounced cranial crests and knobs and is found from extreme southern Virginia to the Mississippi River, west to Louisiana and south through Florida to the lower Keys. There is also a disjunct population in the Upper Piedmont and Blue Ridge of extreme western South Carolina (Conant and Collins 1998). The Southern Toad is particularly abundant in sandy habitats in wooded and open areas where it becomes active at dusk and forages into the evening. Although a great deal of information is available on the natural history of the Southern Toad (Blem 1979), comparatively little is known about its helminth parasites (see Dickey 1921; Jewell 1916; Pryor and Greiner 2004; Sears et al. 2012; Walton 1938, 1940). Here, we report new host and distributional records for some parasites of Southern Toads studied in Florida. Methods We collected 18 juvenile and adult Southern Toads by hand on 28 March (n = 1), 3 May 2014 (n = 9), and 27 July 2015 (n = 8) (12 males, 6 females, mean ± 1 SD snout-vent length [SVL] = 56.0 ± 20.1, range = 30–100 mm) from Topsail 1Science and Mathematics Division, Eastern Oklahoma State College, Idabel, OK 74745. 2Department of Biology, Pennsylvania State University-Shenango Valley Campus, Sharon, PA 16145. 3Life Sciences, Northwest Arkansas Community College, Bentonville, AR 72712. 4Department of Biological Sciences, Arkansas State University, State University, AR 72467. 5Department of Biology, Georgia Southern University, 4324 Old Register Road, Statesboro, GA 30458. *Corresponding author - cmcallister@se.edu. Manuscript Editor: David Bruce Conn Southeastern Naturalist C.T. McAllister, C.R. Bursey, M.B. Connior, S.E. Trauth, and L.A. Durden 2015 Vol. 14, No. 4 642 Hill Preserve State Park, Walton County, FL (30°22'11.3"N, 86°17'48.1"W). We placed all specimens in individual bags on ice and transported them to the laboratory within 48 hr for necropsy. Following procedures for humane treatment of amphibians (HACC 2004), we overdosed the toads with a concentrated Chloretone solution (Lab Connections, St. Augustine, FL), and examined their tegument for ectoparasites. We used dissecting scissors and fine forceps to carefully remove Hannemania sp. (chigger mites) from encapsulations on hosts and stored the samples in vials of 70% ethanol until they could be cleared in lactophenol, slide-mounted in Hoyer’s medium (Walter and Krantz 2009), and identified using appropriate guides (Brennan and Goff 1977, Hyland 1956, Loomis 1956). To collect endoparasites, we made a mid-ventral incision from mouth to cloaca, removed the gastrointestinal tract and other organs, and placed them in a Petri dish containing 0.6% saline for study under a stereomicroscope. We examined the gall bladder for myxozoans following methods of McAllister and Trauth (1995). We used standard histological techniques to prepare tissues for light microscopy following Presnell and Schreibman (1997). We dehydrated the tissues in a graded series of increasing ethanol solutions (70–100%), cleared them with xylene, and infiltrated and embedded in paraffin wax all samples. We trimmed each paraffin tissue block and used a rotary microtome to sagittally section the samples into 8-μm-thick ribbons. We affixed the ribbons to microscope slides using Haupt’s adhesive on a slide warmer while floating them on a 2% neutral-buffered formalin solution. We stained the slides using Harris hematoxylin followed by counterstaining with eosin (H & E), and applied coverslips using Permount® (Fisher Scientific) mounting medium. We used a Nikon Eclipse 600 epifluorescent light microscope with a Nikon DXM 1200C digital camera (Nikon Instruments Inc., Melville, NY) for photomicroscopy and used the same camera mounted on a Nikon SM2800 stereomicroscope for macrophotography. We used hot tap water to kill trematode specimens, which we then fixed in 70% DNA-grade ethanol, stained with acetocarmine, and mounted samples in Canada balsam. We fixed nematodes in hot 70% DNA-grade ethanol and placed each sample on a glass slide in a drop of undiluted glycerol for identification. We deposited voucher specimens of ectoparasites in the general ectoparasite collection in the Department of Biology at Georgia Southern University, Statesboro, GA (accession nos. L 3683–84) and deposited voucher specimens of helminths in the Harold W. Manter Laboratory of Parasitology (HWML), University of Nebraska, Lincoln, NE. We deposited host vouchers in the Arkansas State University Museum, Herpetological Collection (ASUMZ), Jonesboro, AR. We provide prevalence, mean intensity, and range of infection (Bush et al. 1997). Scientific names of amphibians follow Frost (2014). Results and Discussion Fourteen (78%) Southern Toads were infected or infested with parasites as follows: 2 (11%) with Megalodiscus temperatus (Stafford) Harwood (HWML 64779), 1 (6%) with tetrathyridia of Mesocestoides sp. (HWML 75381), 3 (17%) with Cylindrotaenia americana Jewell (retained in C.T. McAllister’s personal Southeastern Naturalist 643 C.T. McAllister, C.R. Bursey, M.B. Connior, S.E. Trauth, and L.A. Durden 2015 Vol. 14, No. 4 collection), 9 (50%) with Cosmocercoides variabilis (Harwood) Travassos (HWML 64780), 10 (55%) with Oswaldocruzia pipiens (Travassos) (HWML 64781), 2 (11%) with 3rd-stage larval Physaloptera sp. (HWML 64782), and 2 (11%) with larval Hannemania hegeneri Hyland (a chigger mite). We observed multiple infections/infestations of helminths and/or arthropods in 7 (39%) of these hosts and documented several new host and geographic-distribution records. We found no myxozoans in the gall bladder. We observed trematodes of Megalodiscus temperatus in the rectum of Southern Toad (2 host-toads with 1 trematode each). This organism has been reported from a variety of anurans, including 3 bufonids, A. americanus americanus Holbrook (American Toad) from Iowa and ON, Canada, A. fowleri Hinkley (Fowler’s Toad) from Virginia, and A. woodhousii Girard (Woodhouse’s Toad) from Nebraska (Bolek and Janovy 2008, Campbell 1968, Stafford 1905, Ulmer 1970). Megalodiscus temperatus has also been found in caudate amphibians and anurans from Florida (Loftin 1960, Manter 1938, Parker 1941). Megalodiscus temperatus eggs are embryonated when laid, and miracidia hatch and penetrate snails of 3 species of Planorbella (= Helosoma) in which they develop into sporocysts. Cercariae develop into daughter rediae in the snail hepatopancreas and after leaving the snail, they encyst as metacercaria in the skin of metamorphosed anurans. Frogs become infected when they ingest tadpoles or pieces of shed skin, and the adult worm develops in the rectum. Tadpoles become infected when they ingest the Megalodiscus metacercariae, which encyst on the bottom of the waterbody. In tadpoles that successfully undergo metamorphosis into juvenile frogs, M. temperatus flukes migrate up to the stomach and then back to the rectum (Bolek and Janovy 2008, Krull and Price 1932). Our observations represent a new host record for M. temperatus. The abundant Mesocestoides sp. tetrathyridia that we observed in the liver of Southern Toads possessed characteristic individual features of the non-proliferative type with a single invaginated scolex, a generally deep invagination canal, a prominent single excretory pore at the end opposite the scolex, and a solid hindbody (Fig. 1; also see Conn et al. 2002). Adult Mesocestoides tapeworms are cosmopolitan parasites of placental mammals, birds, and rarely humans (Padgett et al. 2012). The tetrathyridial stage is often found in the body cavity and encapsulated in tissues of vertebrate 2nd-intermediate hosts such as amphibians, reptiles, and rodents. Recently, McAllister et al. (2014b) provided a summary of North American anuran hosts of Mesocestoides sp. that included the following bufonid hosts: American Toad, Anaxyrus americanus charlesmithi (Bragg) (Dwarf American Toad), A. cognatus Say (Great Plains Toad), Fowler’s Toad, A. houstonensis Sanders (Houston Toad), and Incilius nebulifer (Girard) (Coastal-Plain Toad). To date, this tapeworm has been reported in amphibians from 11 (22%) states including Arkansas, California, Iowa, Kansas, Michigan, Nebraska, New York, Oklahoma, South Dakota, Texas, and Wisconsin. We document for the first time, Mesocestoides sp. in Southern Toad and in Florida. We collected a total of 19 (mean ± 1SD = 6.3 ± 7.5, range = 2–15) Cylindrotaenia americana from the small intestine of Southern Toad. This nematotaeniid Southeastern Naturalist C.T. McAllister, C.R. Bursey, M.B. Connior, S.E. Trauth, and L.A. Durden 2015 Vol. 14, No. 4 644 tapeworm was originally reported from Southern Toad (as Bufo lentiginosus Shaw) from an unknown locality (Jewell 1916). Cylindrotaenia americana has a large geographic range in the US as well as in Canada, the Caribbean, Central America, Mexico, and South America (see McAllister et al. 2013) and has been previously reported from Florida in Scincella lateralis (Say in James) (Ground Skink; Brooks 1972). We found 23 Cosmocercoides variabilis nematodes (8 males, 15 females, 4.0 ± 3.6, 1–8) in the lower intestinal tract of Southern Toad. Cosmocercoides variabilis is a very common intestinal parasite of North American amphibians and reptiles (see recent summation by Bursey et al. 2012). In Florida, C. variabilis has been reported from Southern Toad (Walton 1940) and Oak Toad (Hamilton 1955). This nematode has been previously reported from several other states including, Arizona, Arkansas, California, Idaho, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Nebraska, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, South Dakota, Texas, Utah, Virginia, Washington, West Virginia, and Wisconsin; the overall distribution also includes Alberta, British Columbia, New Brunswick, and Quebec, Canada; and Baja California Norte, Mexico; Costa Rica; and Panama (see Bursey et al. 2012, Connior et al. 2015). We report C. variabilis in Southern Toad for the second time. Figure 1. Mesocestoides sp. tetrathyridia from liver (near the kidneys) of Southern Toad showing solid hindbody (H) below the scolex (S). Southeastern Naturalist 645 C.T. McAllister, C.R. Bursey, M.B. Connior, S.E. Trauth, and L.A. Durden 2015 Vol. 14, No. 4 We found 6 third-stage larval Physaloptera sp. (1 in 1 host, 5 in another host) in Southern Toad stomachs. They are common nematodes of many other anurans, including Oak Toad in Florida (Goldberg and Bursey 1996) as well as other bufonids in Arizona, California, New Mexico, North Carolina, Ohio, Oklahoma, Texas, Utah, and Virginia (see summary by Goldberg et al. 2009). Species assigned to Physaloptera reach maturity in reptiles, birds, and mammals; they require an insect intermediate host, and infection can be acquired from ingesting insects containing infective larvae (Anderson 2000). Larvae ingested by possible paratenic hosts generally attach to the gastric mucosa and can persist for varying periods of time; alternately, infective larvae have been found encapsulated in the stomach wall of various paratenic hosts (Anderson 2000). We found the larva in the stomach lumen; thus, it is not possible to determine if Southern Toad represents a paratenic host and the unencysted larvae would be infective to the next host in the life cycle. This is the first report of larval Physaloptera in Southern Toad. We recovered 29 Oswaldocruzia pipiens Walton strongylid nematodes (9 males, 20 females, 5.0 ± 4.8, 1–13) from the small intestine of Southern Toad. The species has been previously reported from various anurans from North America, including American Toad, Dwarf American Toad, Anaxyrus boreas (Baird & Girard) (Western Toad), Great Plains Toad, Fowler’s Toad, A. hemiophrys Cope (Canadian Toad), Houston Toad, A. punctatus (Baird & Girard) (Red-spotted Toad), A. retiformis (Sanders & Smith) (Sonoran Green Toad), and Woodhouse’s Toad from Arizona, Arkansas, California, Colorado, Georgia, Massachusetts, Michigan, North Carolina, Ohio, Oklahoma, Tennessee, Texas, Virginia, West Virginia, and Wisconsin, and Alberta and Ontario, Canada (see McAllister et al. 2014a). Harwood (1932) previously reported O. pipiens in Southern Toad from Texas; however, this host was misidentified and was actually the Houston Toad (see Thomas et al. 1984). Therefore, this is the first time O. pipiens has been reported from Southern Toad and Florida. Hannemania hegeneri was originally described from Lithobates sphenocephalus utricularius Cope (Southern Leopard Frog) from Sarasota, FL (Hyland 1956). Loomis (1956) recorded this chigger mite from various amphibians in Arkansas, Kansas, Missouri, Oklahoma, Nebraska, and Texas under the synonym Hannemania multifemorala. Although he recorded it from Bufo terrestris in Arkansas, that host (currently treated as Anaxyrus terrestris [Southern Toad]) is not known to occur in Arkansas; thus, the host identification must have been an error. Crossley and Proctor (1971) also recorded H. hegeneri from Southern Leopard Frog (as Rana pipiens) and Acris crepitans (Baird) (Northern Cricket Frog) in Georgia. Walters et al. (2011) listed H. hegeneri and H. multifemorala as separate species, recording H. hegeneri from amphibians in Florida and Georgia and H. multifemorala from amphibians in Alaska, Arkansas, Kansas, Missouri, Nebraska, Oklahoma, and Texas. We question the Alaska report because of its distance from the other records and wonder if this was an unintentional repeat of the Arkansas records because states were listed by their 2-letter abbreviations by Walters et al. (2011) with both AK and AR and NB and NE listed (NE is the correct abbreviation for Nebraska). Crossley Southeastern Naturalist C.T. McAllister, C.R. Bursey, M.B. Connior, S.E. Trauth, and L.A. Durden 2015 Vol. 14, No. 4 646 (1960) described the nymph of H. hegeneri based on specimens from Nebraska and Texas, and Hyland (1961) described the life cycle based on specimens reared from Sarasota, FL. As with other members of the genus, unfed larvae of H. hegeneri penetrate the connective tissue of the host dermis where a localized host-tissue reaction forms an envelope or cyst around the chigger mite (Hyland 1961). Engorgement of H. hegeneri larvae is prolonged, taking 2–3 wk; engorged larvae may remain inside the host cyst for an additional period of time so that the total on-host phase can be as long as 6 mo (Hyland 1961). Currently, the helminth and arthropod parasite list for Southern Toad contains 2 trematode species, 3 cestode species, 5 nematode species, and 1 arthropod (Table 1). Further surveys on Southern Toad from other parts of its range (including disjunct populations) may, in time, increase the number of known parasites; however, our survey supports Aho’s (1990) suggestion that like most amphibians, Southern Toad harbors a depauperate noninteractive helminth community. Acknowledgments The Florida Fish and Wildlife Conservation Commission provided a scientific collecting permit (# LSSC 13-00033) to M.B. Connior. We thank Dr. S. L. Gardner (HWML) for expert curatorial assistance. Table 1. Summary of helminth and arthropod parasites reported from Southern Toad. Prevalence = number infected/number examined (percent). Helminth Locality Prevalence Reference Trematoda Megalodiscus temperatus1 Florida 2/18 (11%) This report Reniferinae (cercaria)2 Florida Not given Sears et al. (2012) Cestoidea Cylindrotaenia americana Not given Not given Jewell (1916) Florida 3/18 (17%) This report Distoichometra bufonis Dickey Georgia Not given Dickey (1921) Mesocestoides sp.1, 3 Florida 1/18 (6%) This report Nematoda Cosmocercoides variabilis Florida Not given Walton (1940) Florida 9/18 (50%) This report Gyrinicola batrachiensis4 (Walton) Florida 1/1 (100%) Pryor and Greiner (2004) Oswaldocruzia pipiens1, 3 Florida 10/18 (55%) This report Physaloptera sp.1 Florida 2/18 (11%) This report Rhabdias americanus Baker Florida Not given Walton (1938) Arthropoda Hannemania hegeneri1 Florida 2/18 (11%) This report 1New host record. 2Experimental infection. 3New distribution record. 4Tadpoles only. Southeastern Naturalist 647 C.T. McAllister, C.R. Bursey, M.B. Connior, S.E. Trauth, and L.A. Durden 2015 Vol. 14, No. 4 Literature Cited Aho, J.M. 1990. Helminth communities of amphibians and reptiles: Comparative approaches to understanding patterns and processes. Pp. 157–195, In G.W. 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