Helminth Communities in the Burrowing Toad, Rhinella Fernandezae, from Northeastern Argentina

Biologia 68/6: 1155—1162, 2013 Section Zoology DOI: 10.2478/s11756-013-0272-5

Helminth communities in the burrowing toad, Rhinella fernandezae, from Northeastern Argentina

Monika Inés Hamann, Arturo Ignacio Kehr & Cynthya Elizabeth González

Consejo Nacional de Investigaciones Cientíﬁcas y Técnicas, Centro de Ecología Aplicada del Litoral, Ruta 5 Km 2.5, W 3400 AMD, Corrientes, Argentina; e-mail: monika [email protected]

Abstract: The main goals of this study were to determine the richness and diversity of helminth parasites of Rhinella fernandezae at the component and infracommunity levels and determine the ecological implications of different biotic and abiotic factors. Specimens were collected near the city of Corrientes, Corrientes Province, Argentina. Prevalence of infection was 94% in the specimens examined (n = 65). The helminth component community in R. fernandezae in this area was comprised a total of 22 species. Of all helminth species, only three (Catadiscus inopinatus, Cosmocerca podicipinus and C. parva) were dominant (importance value: I > 1.0) in the community. The most abundant species were B. tetracotyloides (d = 0.43) among the larvae and C. podicipinus (d = 0.09) among adult worms. At the infracommunity level, the mean individual species richness (2.28 ± 1.48) (mean ± SD) was no more than 3 helminth species per infected host; the diversity and equitability of helminths were 0.23 ± 0.21 and 0.48 ± 0.38, respectively. The host body size was the main factor in determining the parasite abundance. Species richness was significantly and positively correlated with host body size. The parasite helminth species predominantly showed an overdispersed pattern of distribution. Helminth species showed two negative and significant pairs of covariation and one significant pair of association (P < 0.05). R. fernandezae has a wide variety of parasites relating to the host microhabitat, mobility and feeding habits. Key words: ecology; parasites; amphibian; Bufonidae; Rhinella fernandezae; Argentina

Introduction their host and environment, which underlie the structure of the helminth community, are still scarce During the last few years, studies about helminth par- (Hamann et al. 2006a, b, 2010, 2012). Specifically, ex- asite communities of Argentinean amphibians have be- tensive examination of many additional host species come more frequent. These studies have contributed to is needed before the helminth diversity of Argen- the understanding the patterns and processes involved tinean amphibians can be adequately known, as well in helminth community structure, and the role of para- as for making robust predictions about parasite speci- site in the ecosystems. In this context, extrinsic factors ficity (generalist vs. specialist), importance of a species such as anthropogenic disturbance (e.g., environments within the community, e.g., dominant helminth species, perturbed by intensive agricultural activity) and natu- and characteristics of the helminth communities (inter- ral habitat conditions are keys for helminth community active vs. isolationist). Likewise, the spatial and tem- organization in host amphibians (Hamann et al. 2006b). poral variations of larval parasites and the coloniza- At the same time, intrinsic factors such as reproductive tion abilities of parasites which could also influence the cycle of the host, relative vagility, feeding preference in parasite assemblage in the definitive host (Esch et al. terms of foraging behaviour, range of prey species, host 2002). So far, the present study is the first one investi- body size, and the life cycle of parasite are key fac- gating the ecological aspects of all groups of parasitic tors determining parasite abundance and species rich- helminths (i.e., platyhelminths, nematodes and acan- ness (Hamann et al. 2006a, b, 2010, 2012, 2013). This thocephalan) in terrestrial amphibians from Argentina, variety of processes related to the parasites, their host at the component and infracommunity levels. or its habitat have been identified by several authors Based on certain assumptions, the approach em- (Goater et al. 1987; Aho 1990; Muzzall 1991; McAlpine ployed in the current study predicted that (1) the di- 1997; Bolek & Coggins 2003; Yoder & Coggins 2007; versity of the helminth parasite community is deter- Marcogliese et al. 2009) as causes of the depauperate, mined by given habitat and the reproductive cycle of and high variability of the helminth communities in am- the host; (2) the helminth parasite populations may phibians from temperate latitudes. serve as markers of diet of the host; and (3) terrestrial In our region, despite the existence of a greatly amphibians mostly host the greater number of nema- diverse amphibian fauna (Frost 2011), studies that fo- tode species than aquatic amphibians. These premises cus on the ecological interrelationships of the helminths, are tested through analysis of the helminth parasite

c 2013 Institute of Zoology, Slovak Academy of Sciences 1156 M.I. Hamann et al. communities of the burrowing toad Rhinella fernan- Haematoloechus longiplexus Stafford, 1902; 09111007, Gor- dezae (Gallardo, 1957). This anuran species occurs in goderina parvicava Travassos, 1922; 09111007, Bursotrema Argentina, Brazil, Paraguay and Uruguay (Frost 2011); tetracotyloides Szidat, 1960; 09111006, Travtrema aff. steno- the adult microhabitat includes a preference for dry cotyle Cohn, 1902; 08100104, Opisthogonimus sp.; 09111006, land and usually uses burrows or natural cavities. Also, Styphlodora sp.; 09020603, Apharyngostrigea sp.; 09020901, Apatemon sp.; 09020901, Strigeidae gen. sp.; 09111004, R. fernandezae returns to the water for reproduction, Cylindrotaenia sp.; 08102211, Oswaldocruzia subaricularis and vocalizes in areas such as vegetation mounds in (Rudolphi, 1819); 08102207, Rhabdias aff. sphaerocephala flooded areas. The breeding season occurs in spring, Goodey, 1924; 08102212, Cosmocerca podicipinus Baker summer, and autumn. This burrowing toad has an in- and Vaucher, 1984; 09111002, Cosmocerca parva Travas- termediate (between generalist and specialist) diet type sos, 1925; 09020604, Ortleppascaris sp.; 09020606, Rhabdo- dominated by ants and coleopterans, and employs an chonidae gen. sp.; 08102206, Seuratoidea gen. sp.; 08102210, actively foraging predatory strategy (Duré et al. 2009; Physaloptera sp.; and 09020606, Centrorhynchus sp.]. Sanchez et al. 2010). Statistical analysis The aims of this study were: (1) to determine the The infection prevalence, intensity, and abundance were cal- helminth parasite fauna of R. fernandezae;(2)tode- culated for helminths following Bush et al. (1997). Commu- termine the richness and diversity of parasites at the nity richness and diversity were estimated through the fol- component and infracommunity levels; (3) to analyze lowing: total number of helminth species (= richness), Shan- the relationships between helminth and host character- non index (H ) (Shannon & Weaver 1949), and evenness istics; and (4) to identify and examine species affinities (J )asH /H maximum (Zar 2010). The diversity index was in helminth communities. used with decimal logarithms (log10). The Berger-Parker index of dominance (d) was used to determine the most abundant species (Magurran 2004). All values are expressed as Material and methods the mean ± standard deviation (SD). The helminth community structure was examined according to the methodology Study area outlined by Thul et al. (1985), in which helminth species are The study area was located ∼15 km east of the city of Cor- ◦ ◦ classified into four groups (dominant, codominant, subordi- rientes (27 30 S, 58 45 W). Although limited to 30 ha, the nate and unsuccessful) by taking into account their preva- predominant vegetation in the study area is forest with an lence, intensity, and maturation factor, which is related to herbaceous stratum comprising grasslands, numerous cacti thedegreeofhostspecificity.Theimportancevalue(I ), was and terrestrial bromeliads. The habitat is also character- calculated for each helminth species as follows: ized by temporary, semi-permanent, and permanent ponds. A B The aquatic vegetation in a permanent pond (30 m long, M j j Ij =( j ) 22 100 15 m wide, and 0.8 m deep) sampled in this study consisted AiBi of floating and submerged hydrophytes, surrounded by sev- i=1 eral species of grasses. The mean annual temperature for the where Aj = number of individual parasites in species j, Bj ◦ area is 23 C, and the mean annual precipitation is 1500 mm, = number of hosts infected with parasite j,andMj is a without a well-defined dry season, although periods of rain maturity factor equal to 1.0 if at least one mature specimen shortage occur every 4–6 years (Carnevali 1994). of species j is found and equal to 0 otherwise. Helminth communities were classified at the infracom- Collection and examination of amphibians munity level (i.e., all helminth infrapopulations within a sin- Sixty-five specimens of R. fernandezae were collected be- gle burrowing toad) and component community level (i.e., tween Sept. 2003 and Nov. 2009. Toads were hand-captured, all helminth infracommunities within a population of bur- mainly at night, using the sampling technique defined as the rowing toad) (Esch et al. 2002). Spearman’s rank test (rs) “visual encounters survey” (Crump & Scott 1994). Spec- was used to assess the relationship between the host body imens were transported live to the laboratory, killed in a size and infracommunity descriptors and calculate possible chloroform (CHCL3) solution and their snout-vent length correlations between the host body size and parasite abun- (SVL) and body weight (BW) were recorded. At necropsy, dances. Species co-variation was analyzed with the Spear- hosts were sexed and the oesophagus, stomach, gut, lungs, man test correlation. Species associations were analyzed us- liver, urinary bladder, kidneys, body cavity, musculature, in- ingaChi-squaredtest(χ2), with the Yates correction for tegument, and brain were examined for parasites. Helminths continuity. The variance/mean ratio was used to determine were observed in vivo, counted, killed in hot distilled wa- the spatial distribution of parasites. Calculations were made ter, and preserved in 70% ethyl alcohol. Digeneans, ces- using the software Xlstat 7.5 (Addinsoft 2004). For studies todes, and acanthocephalans were stained with hydrochlo- of correlations and associations, only the species that had at ric carmine, cleared in creosote, and mounted in Canada least 10% occurrences in each of the amphibian populations balsam. Nematodes were cleared in glycerine or lactophe- (eight species) were considered. nol, and examined as temporary mounts. Systematic de- termination of helminths was carried out following Yam- Results aguti (1961, 1963, 1975), Gibson et al. (2002), Jones et al. (2005), and Bray et al. (2008). Specimens of parasite species Community structure analysis were deposited in the Helminthological Collection of Cen- The helminth component community of this toad pop- tro de Ecología Aplicada del Litoral (CECOAL), Consejo Nacional de Investigaciones Científicas y Técnicas (CON- ulation consisted of 22 helminth species (Table 1). The ICET), Corrientes, Argentina [accession numbers CECOAL, predominant groups of helminth parasites (larval and 08100110, Catadiscus inopinatus Freitas, 1841; 08102208, adult) were trematodes (12 species) followed by nema- Catadiscus marinholutzi Freitas and Lent, 1939; 09111006, todes (8); other groups of parasites were represented by Helminths in Rhinella fernandezae from Argentina 1157

Table 1. Helminth parasites record of Rhinella fernandezae from Corrientes, Argentina.

Infection parameters b c Helminth Stage √ Sites S2/ x %MA± 1SD MI± 1SD

Catadiscus inopinatus Adult 10.3 20.0 0.9 ± 3.0 4.1 ± 5.4 Li Catadiscus marinholutzia Adult 0.0 1.5 0.0 ± 0.1 1.0 ± 0.0 Li Haematoloechus longiplexusa Adult 5.0 3.1 0.1 ± 0.7 4.0 ± 1.0 Lu Gorgoderina parvicavaa Adult 15.8 6.0 0.8 ± 3.6 12.3 ± 7.8 Ub Bursotrema tetracotyloidesa Larva 66.4 37.0 9.2 ± 24.7 24.8 ± 35.5 K Travtrema aff. stenocotylea Larva 14.0 43.0 3.1 ± 6.6 7.1 ± 8.4 B-M Opisthogonimus sp.a Larva 2.3 13.0 0.3 ± 0.8 1.8 ± 1.2 B-M Nephrostomumsp. a Larva 2.0 1.5 0.1 ± 0.5 4.0 ± 0.0 K Styphlodora sp.a Larva 22.6 13.0 1.9 ± 6.7 12.6 ± 12.5 K Apharyngostrigea sp.a Larva 0.0 1.5 0.0 ± 0.1 1.0 ± 0.0 B Apatemon sp.a Larva 0.0 1.5 0.0 ± 0.1 1.0 ± 0.0 B Strigeidae gen. sp. Larva 0.0 1.5 0.0 ± 0.1 1.0 ± 0.0 L Oswaldocruzia subaricularisa Adult 0.1 1.5 0.0 ± 0.4 3.0 ± 0.0 Si-Li Rhabdias aff. sphaerocephalaa Adult 56.1 1.5 0.8 ± 6.7 54.0 ± 0.0 Lu Cosmocerca podicipinus Adult 8.2 29.0 1.9 ± 3.9 6.3 ± 4.9 Si-Li Cosmocerca parva Adult 14.4 11.0 1.2 ± 4.1 10.9 ± 7.3 Si-Li Rhabdochonidae gen. sp. Larva 0.1 1.5 0.0 ± 0.4 3.0 ± 0.0 S Seuratoidea gen. sp.a Larva 7.7 6.1 0.3 ± 1.5 4.0 ± 4.6 S Physaloptera sp. Larva 9.5 3.1 0.2 ± 1.4 6.0 ± 5.0 S Ortleppascaris sp. Larva 0.1 1.5 0.1 ± 0.4 3.0 ± 0.0 L Cylindrotaenia sp.a Adult 3.0 8.0 0.1 ± 0.6 1.8 ± 1.2 Si Centrorhynchus sp. Larva 5.0 17.0 0.4 ± 1.4 2.4 ± 2.7 S-M √ Explanations: a New host; b Dispersion (S2/ x), prevalence (%), mean abundance (MA) ± 1 SD, mean intensity (MI) ± 1SD;c Site of infection: K – kidneys, B – body cavity, P – pharyngeal zone, Si – small intestine, Li – large intestine, S – serous of stomach, M – mesenteries, Lu – lungs, L – liver, Ub – urinary bladder. only 1 species (Cestoda: Cylindrotaenia sp. and Acan- thocephala: Centrorhynchus sp.). The infection prevalence was 94% for the 65 toads examined. Helminth diversity was 0.84 and evenness was 0.64. The most abundant species were Cosmocerca podicipinus (d = 0.09) within the group of adult worms and Bursotrema tetracotyloides (d = 0.43) in the larvae group. Most helminth parasites (0.68%) showed aggregated patterns of distribution. Only 8 parasite species were found in the intestine with prevalence >10% (Table 1). Of all adult specimens of helminths examined, the primary site of Fig. 1. Observed and expected frequency distribution of helminth infection was the digestive tract, except for Haema- infracommunity species richness in Rhinella fernandezae,accord- toloechus longiplexus and Rhabdias aff. sphaerocephala ing to Poisson distribution pattern. that were found in the lungs. Four helminth species are assumed to have indirect life cycles (Catadiscus marinholutzi, Catadiscus inopinatus, Gorgoderina parvicava nificant: C. podicipinus/T. aff. stenocotyle and C. podi- and H. longiplexus), and 5 are assumed to have direct cipinus/B. tetracotyloides (Table 3). One association life cycles (Cylindrotaenia sp., Oswaldocruzia subari- was found among the eight species analyzed: C. podi- cularis, Cosmocerca parva, C. podicipinus,andR. aff. cipinus/B. tetracotiloides (χ2 =4.7;df=1;P < 0.05). sphaerocephala)(Table2). At the infracommunity level, the mean helminth Infection in relation to host body size richness was 2.28 ± 1.48 (mean ± SD) (maximum = 6) The total lengths of the burrowing toads ranged from species per infected burrowing toad. Multiple infections 22.00 to 70.00 (48.54 ± 11.78) mm, and their weights were observed in 63% of toads, with 2, 3, 4, 5, and 6 ranged from 0.75 to 27.40 (11.42 ± 6.28) g. Infracom- species occurring in 16, 13, 5, 5, and 2 toads, respec- munity richness was significantly correlated with the tively. The observed distribution of helminth infracom- host body size (length: rs = 0.40, n = 61, P < 0.05, munity species richness showed a good fit to the Poisson and weight: rs = 0.37, n = 61, P < 0.05); significant distribution (χ2 =4.65,df=5,P = 0.46) (Fig. 1). The correlations were also found between the abundances mean helminth diversity was 0.23 ± 0.21 and evenness of helminth species and the host body size (Table 4). was 0.48 ± 0.38. The length of female burrowing toads ranged from 23.00 to 70.00 (44.00 ± 13.00) mm, and their weight Species affinity in the infracommunity ranged from 2.00 to 27.00 (9.00 ± 7.00) g. Both vari- Two correlations between species were negative and sig- ables were significantly correlated with infracommunity 1158 M.I. Hamann et al.

Table 2. Summary of helminth life cycles in Rhinella fernandezae from Corrientes, Argentina.

HOSTS HELMINTHS Reference c First intermediate Second intermediate Deﬁnitive

Travtrema aff. stenocotyle Aquatic snail Amphibian Snake Ostrowski de Núñez (1979) Opisthogonimus sp. Aquatic snail Amphibian Snake Grabda-Kazubska (1963) Styphlodora sp. Aquatic snail Amphibian Snake Grabda-Kazubska (1963) Bursotrema tetracotyloides Aquatic snail Amphibian Mammal Yamaguti (1975) Apharingostrigea sp. Aquatic snail Amphibian Bird Yamaguti (1975) Apatemon sp. Aquatic snail Amphibian Bird Yamaguti (1975) Strigeidae gen. sp. Aquatic snail Amphibian Bird-Mammalb Yamaguti (1975) Nephrostomum sp. Aquatic snail Amphibian Bird Ostrowski de Núñez (1974) Haematoloechus longiplexus Aquatic snail Aquatic insect larva Amphibian Smyth & Smyth (1980) Catadiscus inopinatus Aquatic snail Aquatic vegetation Amphibian Ostrowski de Núñez(1978) Catadiscus marinolutzi Aquatic snail Aquatic vegetation Amphibian Ostrowski de Núñez(1978) Gorgoderina parvicava Aquatic clams Aquatic insect larvae Tadpoles Amphibian Bolek et al. (2009) Cosmocerca podicipinus – – Amphibian Fotedar & Tikoo (1968) Cosmocerca parva – – Amphibian Fotedar & Tikoo (1968) Rhabdias aff. sphaerocephala – – Amphibian Anderson (2000) Oswaldocruzia subauricularis – – Amphibian Anderson (2000) Rhabdochonidae gen. sp. Insect larvas Amphibiana Fish Moravec (1977) Physaloptera sp. Insect-isopod Amphibiana Snake-Bird-Mammalb Schmidt (1985) Seuratoidea gen. sp. Invertebrate Amphibiana Snakeb Anderson (2000) Otleppascaris sp. Invertebrate Amphibiana Snake Anderson (2000) Centrorhynchus sp. Insect Amphibiana Bird Schmidt (1985) Cylindrotaenia sp. – – Amphibian Prudhoe & Bray (1982)

Explanations: a Paratenic host, b Possible deﬁnitive hosts, c References: life cycles of congener species or species of the same family.

Table 3. Co-variation based on Spearman coeﬃcient correlations (rs) among eight common helminth species in Rhinella fernandezae from Corrientes, Argentina.

Helminth Table ID (1) (2) (3) (4) (5) (6) (7) (8)

Catadiscus inopinatus (1) 1.000 Cosmocerca podicipinus (2) 0.007 1.000 Cosmocerca parva (3) 0.026 –0.033 1.000 Styphlodora sp. (4) –0.037 –0.017 0.086 1.000 Opisthogonimus sp. (5) –0.027 –0.098 –0.168 –0.087 1.000 Travtrema aﬀ. stenocotyle (6) –0.206 *–0.263 –0.110 0.182 0.010 1.000 Centrorhynchus sp. (7) –0.173 0.165 0.099 0.021 0.009 –0.039 1.000 Bursotrema tetracotiloides (8) –0.039 *–0.267 0.071 0.193 0.026 0.040 –0.047 1.000

Explanations: * Signiﬁcant at P < 0.05.

Table 4. Spearman correlation (rs) between helminth parasites and the body size of Rhinella fernandezae from Corrientes, Argentina.

Total frogs Male Female Helminth Weight Length Weight Length Weight Length

Infracommunity descriptors Diversity 0.252 *0.285 0.148 0.100 0.370 0.388 Evenness 0.126 0.125 0.051 0.038 0.173 0.213 Richness *0.369 *0.402 0.230 0.197 *0.486 *0.480 Parasitic abundance Catadiscus inopinatus –0.091 –0.158 –0.296 *–0.371 0.247 0.195 Cosmocerca podicipinus 0.032 –0.110 0.030 –0.196 –0.216 –0.216 Cosmocerca parva 0.224 0.238 0.152 0.195 0.355 0.356 Styphlodora sp. *0.365 *0.314 0.178 0.117 *0.554 *0.554 Opisthogonimus sp. –0.003 0.134 –0.082 0.151 –0.072 –0.072 Travtrema aﬀ. stenocotyle 0.218 0.181 0.276 0.215 0.000 0.000 Bursotrema tetracotiloides –0.037 –0.040 –0.128 –0.202 0.262 0.309 Centrorhynchus sp. *0.264 0.242 0.292 0.235 – –

Explanations: * Signiﬁcant at P < 0.05. richness and with abundance of one trematode species to 67.00 (50.91 ± 10.55) mm, and their weight from 0.75 (Table 4). The length of male toads ranged from 22.00 to 20.49 (12.66 ± 5.22) g. These variables were not sig- Helminths in Rhinella fernandezae from Argentina 1159

Table 5. Classification of helminth parasite species in Rhinella Discussion fernandezae from Corrientes, Argentina. In South America, previous reports have found that Helminth parasites classification* Importance value the helminth communities of Rhinella species consisted Dominant species predominantly of nematodes, with richness ranging be- Cosmocerca podicipinus 8.911 tween 2 and 15 species (see Table 6). In the present Catadiscus inopinatus 2.845 study, R. fernandezae presented greater richness (22 Cosmocerca parva 2.079 Codominant species species) with dominance of trematode species (larval Haematoloechus longiplexus 0.063 + adult); nevertheless, when only adult helminths were Rhabdias aff. sphaerocephala 0.211 compared, nematode and trematode species showed an Gorgoderina parvicava 0.766 equal richness. These results demonstrate that R. fer- Cylindrotaenia sp. 0.176 Subordinate species nandezae may act as intermediate and definitive hosts Catadiscus marinolutzi 0.001 for various helminth species (see Table 2). The most Oswaldocruzia subaricularis 0.012 represented larval stages were those whose definitive Unsuccessful pioneer species hosts are mammals (e.g., B. tetracotiloides) and rep- Bursotrema tetracotyloides 0.000 Travtrema aff. stenocotyle 0.000 tiles (e.g., Travtrema aff. stenocotyle), these results sug- Opisthogonimus sp. 0.000 gested that the infections of these metacercariae are Nephrostomum sp. 0.000 indicative of the significant role of R. fernandezae as Styphlodora sp. 0.000 prey item for these definitive hosts. Similar results were Apharyngostrigea sp. 0.000 Apatemon sp. 0.000 recorded in the same area for Leptodactylus chaquensis Strigeidae gen. sp. 0.000 Cei, 1950, Leptodactylus latinasus Jiménez de la Es- Rhabdochonidae gen. sp. 0.000 pada, 1875 and Scinax nasicus (Cope, 1862) (Hamann Seuratoidea gen. sp. 0.000 et al. 2006a, b, 2010). However, this result contrasts Physaloptera sp. 0.000 Ortleppascaris sp. 0.000 with those found in Leptodactylus bufonius Boulenger, Centrorhynchus sp. 0.000 1894 captured in the same area but with a different behavior, i.e., the adult frogs lives in burrows and only * According to the methodology from Thul et al. (1985). leaves to feed, thus resulting in lower values of metacercariae as a consequence of the short length of time of the nificantly correlated with the infracommunity richness, frogs in water (Hamann et al. 2012). Lastly, these larval however, host body size showed negative significant cor- infections could occur in different development stages of relation with the abundance of one species (Table 4). amphibians (Hamann & González 2009; Hamann et al. 2013), thus it could be assumed that amphibians in all Importance of species within the community life stages play an important link in the life cycle of Helminth species were classified according to commu- many helminth species. nity importance values (Table 5); three species were On the other hand, the helminth communities in strongly characteristic of the community (dominant) the present study predominantly consists of species that and four species contributed significantly to the com- had been recorded as infecting more than one species munity, though to a lesser degree. Two species occurred of amphibians; in this sense, Catadiscus inopinatus, infrequently and did not contribute significantly to the Cosmocerca podicipinus and C. parva are compara- community and thirteen that are able to enter the host tively common in other sympatric amphibians (e.g., but not of attaining maturity therein, contributed little L. chaquensis, L. latinasus and L. bufonius see Hamann to the community and are characteristic of a different et al. 2006a, b, 2012), and are also the helminth domi- host. nant species. This group of parasites was represented by

Table 6. Helminth species richness at the component community level for Rhinella species from South America.

Adult Helminth Larval Helminth Host n Total Locality Reference richness N T C A n t c a

R. fernandezae 65 22 4 4 – – 4 8 1 1 Corrientes, Argentina Present study R. ictericus 60 12 7 2 1 – – – 1 1 Santa Catarina, Brazil Santos et al. (2013) R. fernandezae 90 13 5 3 1 1 – 1 1 1 Rio de Janeiro, Brazil Santos & Amato (2010) R. ictericus 155 3––11–––S˜ao Paulo, Brazil Pinh˜ao et al. (2009) R. ictericus 58 12 5 4 2 1 – – – – Santa Catarina, Brazil Lux Hoppe et al. (2008) R. schneideri 42 6 5 – 1 1 – – – – Santa Catarina, Brazil Lux Hoppe et al. (2008) R. ictericus 32 15 13 2 – – – – – – Rio de Janeiro, Brazil Luque et al. (2005) R. typhonius 27 7 5 – – – 1 – – 1 Cuzco, Peru Bursey et al. (2001) R. glaberrimus 1 2 2 – – – – – – – Cuzco, Peru Bursey et al. (2001) R. marinus 5 5 3 – 1 – 1 – – – Cuzco, Peru Bursey et al. (2001)

Explanations: Adult/larval helminths, N/n – nematodes, T/t – trematodes, C/c – cestodes, A/a – acanthocephalans. 1160 M.I. Hamann et al. species that occur entirely in the aquatic environment organs (C. podicipinus + B. tetracotiloides); and on and the host acquire the infection by ingesting metacer- the other, we found a negative correlation between two cariae attached on vegetation or suspended in the water species at different infection sites (e.g., C. podicipinus (e.g., C. inopinatus), as well as by species that inhabit vs. T. aff. stenocotyle). Similarly to other local amphib- both moist soil and dry areas, and make such infections ians (Hamann et al. 2006a, b, 2010, 2012) there was no possible by penetration of infective larvae into the host discernible pattern or structure to R. fernandezae’s in- through the skin (e.g., C. podicipinus). fracommunities, although their proximity to the isola- The most common nematodes were monoxenous tionist extreme of the continuum was demonstrated, as species related to the habitat where R. fernandezae well as the presence of depauperate infracommunities spend more time, i.e., a more terrestrial existence. This when only the adult helminth species are considered. result agrees with previous reports for bufonid amphib- In conclusion, the helminth parasites community ians in temperate region (Bolek & Coggins 2003; Yo- of in R. fernandezae has the following characteristics: der & Coggins 2007) and tropical region (Bursey et larval infections result from acquisition of species by al. 2001; Goldberg & Bursey 2003; Luque et al. 2005; penetration of infective larvae into the host through Ibrahim 2008; Santos et al. 2013). Additionally, when natural orifices or the skin; the most common adult compared to the helminth community of R. fernandezae trematodes immediately infect the definitive host with from Brazil, the latter showed that the cosmocercid ne- cercariae that encyst rapidly in the open vegetation, matode Aplectana meridionalis Lent and Freitas, 1948 and adult nematodes with monoxenous cycles predom- dominated the parasite community (Santos & Amato inate in this community; the wide variety of parasites 2010). Similar conclusions were reported by Ibrahim suggests that the host microhabitat preference, mobil- (2008) who demonstrated that the parasitic community ity and feeding habits play an important role in specific of the maculated toad Amietophrynus regularis (Reuss, composition of this community. 1833) from Egypt is dominated by Aplectana macin- toshii (Stewart, 1914). In both cases, the infective larval stages can infect the host by ingestion or penetra- Acknowledgements tion (Anderson 2000), and so this would indicate the This project was partially supported by Consejo Nacional ability to move with relative freedom between different de Investigaciones Científicas y Técnicas (CONICET) from sites and to stay in contact for long periods with the Argentina, through grant PIP 2945 to M. I. Hamann. terrestrial environment, thus allowing contact with the infective larvae. Furthermore, the habitat and mobility of the hosts associated to their search of prey would References favour the penetration of infective larvae; thus resulting Addinsoft. 2004. Xlstat for Excel, version 7. 5. Addinsoft, Lon- in the richest and most diverse helminth communities. don, 104 pp. Regarding amphibian body size, researchers have Aho J.M. 1990. Helminth communities of amphibians and rep- previously stated that this variable influences the num- tiles: comparative approaches to understanding patterns and ber of helminth species and parasite abundance (Muz- processes, pp. 157–196. In: Esch G.W., Bush A.O. & Aho J.M. (eds), Parasite Communities: Patterns and Processes, Chap- zall 1991; McAlpine 1997; Bolek & Coggins 2000; Kehr man & Hall, London, 304 pp. ISBN-10: 0412335409, ISBN-13: et al. 2000; Yoder & Coggins 2007; Ibrahim 2008 9780412335402 Hamann et al. 2010, 2012). In the present study, the size Anderson R.C. 2000. Nematode Parasites of Vertebrates: Their nd of R. fernandezae individuals was a determining factor Development and Transmission. 2 ed. CABI International, for parasite species richness, which suggests that larger Oxford, 650 pp. ISBN: 0-85199-421-0 Bolek M.G. & Coggins J.R. 2000. Seasonal occurrence and com- size is related with a longer life of the hosts and con- munity structure of helminth parasites from the eastern sequently more time to become infected, which favours American toad, Bufo americanus americanus,fromsouth- higher values of parasitism and species richness, and eastern Wisconsin, USA. Comp. Parasitol. 67: 202–209. also with a greater surface area vulnerable to parasite Bolek M.G. & Coggins J.R. 2003. Helminth community structure of sympatric eastern American toad, Bufo americanus ameri- colonization, i.e., greater probability of skin penetration canus, northern leopard frog, Rana pipiens, and blue-spotted by larval stages. Larger females were also more-heavily salamander, Ambystoma laterale, from southeastern Wiscon- parasitized (e.g., species richness), suggesting that the sin. J. Parasitol. 89 (4): 673–680. DOI: 10.1645/GE-70R differential behavior of females (e.g., different times in Bolek M.G., Snyder S.D. & Janovy J.Jr. 2009. 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