Native species Maxvachonia chabaudi Mawson, 1972 (Nematoda: Cosmocercoidea) found in the invasive marine toad Rhinella marina (Linnaeus) (Anura: Bufonidae) in Australia.

The genus Maxvachonia Chabaud et Brygoo, 1960 (Ascaridomorpha: Cosmocercidae) is a poorly known group of parasitic nematodes. Species of Maxvachonia are native to Madagascar-Australo-Papuan Region, where they are known to parasitise frogs, snakes and skinks. Unfortunately, most of Maxvachonia species have been inadequately described. In the present study, we report the native species Maxvachonia chabaudi Mawson, 1972 from the intestine of the invasive marine toad Rhinella marina (Linnaeus) in Australia for the first time. We speculate that the marine toads infected with M. chabaudi are likely related to their eating skinks or the similarity in diet/habitat/ecology between the toad and the skinks. The detailed morphology of M. chabaudi was studied using light microscopy and, for the first time, scanning electron microscopy, based on the newly collected specimens. Some characters important for the specific diagnosis of M. chabaudi are reported for the first time, including each lip with distinct inner flanges, the location of vulva varying from anterior to posterior of the oesophageal bulb and the presence of single medio-ventral precloacal papilla. An identification key to the species of Maxvachonia is provided.

Pathology Associated With an Outbreak of Entamoebiasis in Wild Cane Toads (Rhinella marina) in Tropical Australia.

Infection due to Entamoeba spp. is known to cause serious disease in primates (Entamoeba histolytica) and snakes (Entamoeba invadens), but there are no detailed descriptions of the pathology associated with Entamoeba spp. infection in amphibians. In 2014, an outbreak of entamoebiasis associated with a novel species of Entamoeba induced clinical illness and poor body condition in free-ranging cane toads in Australia's Northern Territory. Here, we describe the gross pathology, histology, and clinical pathology linked to the outbreak. The study compared 25 toads with invasive entamoebiasis, defined as histologically visible amoebas within tissue, and 12 toads without invasive entamoebiasis. Grossly, affected toads had mild to marked congestion of colonic serosal vasculature, with variable thickening of the intestinal wall and serosanguineous to hemorrhagic colonic content. Histologically, invasive entamoebiasis manifested primarily as moderate to severe, variably hyperplastic to ulcerative colitis. The small intestine was affected in 10 of 25 toads, and 5 of 25 toads also had gastric lesions. Amoebas consistent in morphology with Entamoeba sp. were commonly intermingled with mucosal epithelium, frequently along the basement membrane, with deeper invasion into the superficial lamina propria in only 5 toads. Toads with invasive entamoebiasis had neutrophilia, monocytosis, and lymphopenia, and thus elevated neutrophil to lymphocyte ratios, suggestive of an inflammatory and/or stress leukogram.

Ocorrência de Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae) em Rhinella icterica (Spix, 1824) (Anura: Bufonidae) em Maricá, Rio de Janeiro, Brasil / Occurrence of Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae) in Rhinella icterica (Spix, 1824) (Anura: Bufonidae) in Maricá, Rio de Janeiro, Brazil / Ocurrencia de Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae) en Rhinella icterica (Spix, 1824) (Anura: Bufonidae) en Maricá, Río de Janeiro, Brasil

Anfíbios anuros são comumente parasitados por carrapatos da espécie Amblyomma rotundatum, os quais possuem alta predileção por animais ectotérmicos. Fêmeas e ninfas ingurgitadas de A. rotundatum foram coletadas em condições naturais a partir de um espécime de "sapo-cururu" da espécie Rhinella icterica. A identificação dos carrapatos foi feita por meio de características morfológicas. Este é o primeiro relato do parasitismo deste carrapato em sapos desta espécie no Município de Maricá, Região Metropolitana do Estado do Rio de Janeiro, Brasil.(AU)

Anuran amphibians are commonly parasitized by ticks of the species Amblyomma rotundatum, which have high predilection for ectothermic animals. Engorged females and nymphs of A. rotundatum were collected under natural conditions from a "toad-cururu" specimen of the species Rhinella icterica. The identification of ticks was made through morphological characteristics. This is the first report of the parasitism of this tick in toads of this species in the Municipality of Maricá, Metropolitan Region of the State of Rio de Janeiro, Brazil.(AU)

Los anfibios anuros son comúnmente parasitados por garrapatas de la especie Amblyomma rotundatum, los cuales poseen alta predilección por animales ectotermos. Las hembras y ninfas ingurgitadas de A. rotundatum fueron recolectadas en condiciones naturales a partir de un espécimen de "sapo cururú" de la especie Rhinella icterica. La identificación de las garrapatas se ha hecho a través de características morfológicas. Este es el primer relato del parasitismo de esta garrapata en sapos de esta especie en el Municipio de Maricá, Región Metropolitana del Estado de Río de Janeiro, Brasil.(AU)

Invasive Colonic Entamoebiasis in Wild Cane Toads, Australia.

We detected a disease syndrome in free-ranging Australian cane toads involving atypical behavior and emaciation that is associated with a previously undescribed Entamoeba sp. that infiltrates the colonic lining, causing it to slough. The organism may become seasonally pathogenic when toads are under hydric and nutritional stress.

Detection of Rickettsia spp. in ticks parasitizing toads (Rhinella marina) in the northern Brazilian Amazon.

This study evaluated rickettsial infection in ticks collected on toads from the northern Brazilian Amazon (Amapá state), where to our knowledge there are neither records of ticks from amphibians nor rickettsial infections in ticks. During 2016-2017, a total of 22 free-living toads were captured and identified as Rhinella marina. Overall, 12 (54.5%) toads were parasitized by a total of 97 ticks (6 males, 39 females, 31 nymphs, 21 larvae), giving a mean intensity of 8.1 ticks per infested toad. Two tick species were morphologically identified: Amblyomma rotundatum Koch (31 females, 14 nymphs), and Amblyomma dissimile Koch (6 males, 8 females, 17 nymphs). The 21 larvae were morphologically denoted as Amblyomma sp. Five toads were co-infested by A. rotundatum and A. dissimile. Morphological identifications were confirmed by nucleotide sequencing of fragments of the mitochondrial genes 16S rDNA, 12S rDNA and/or COX1. A total of 54 ticks were analyzed for the presence of rickettsial DNA. Eleven (9 females and 2 nymphs) out of 14 A. rotundatum ticks contained Rickettsia bellii. None of the 25 specimens of A. dissimile (6 males, 6 females, 13 nymphs) contained amplifiable rickettsial DNA. From 15 Amblyomma sp. larvae, a pool of 10 individuals contained Rickettsia sp. strain Colombianensi. Sequencing of the 16S rDNA amplicon derived from the positive pool yielded a sequence of A. dissimile. We detected Rickettsia sp. strain Colombianensi for the first time in Brazil. Prior records of this agent were restricted to Colombia and Honduras. In addition, we report the presence of A. rotundatum for the first time in the state of Amapá, where the only other record of A. dissimile was registered over 20 years ago.

Helminth infracommunity of the cane toad Rhinella marina (Anura: Bufonidae) within its native distribution range.

During August 2010, a total of 66 cane toad Rhinella marina were collected in Laguna de Coyuca, Guerrero, Mexico and examined for the presence of helminths. Ninety-two percent were parasitized by 1 or more parasite species. A total of 4624 individuals were found, belonging to 8 helminth taxa (1 digenean, 1 cestode and 6 nematodes). Infracommunities harbored by this host species are highly variable (mean Jaccard similarity index 0.31±0.27); mean percent similarity index 0.26±0.32) and depauperate (mean richness 1.91±0.92; mean abundance 64.4±100.34); almost 50% of them were dominated by Rhabdias fuelleborni, a skin-penetrating nematode. Differences related to host gender and size were found, since males registered infracommunities with lower species richness and diversity than females. The reproductive condition of females (collected during the breeding season) might explain the results obtained; during this season, females invest less in resistance to infection in favor of investing resources in reproduction. However, confirmation of this statement can only be made by sampling in the dry season, when the toads do not reach their reproductive peak.

First report of exotic ticks (Amblyomma rotundatum) parasitizing invasive cane toads (Rhinella marina) on the Island of Hawai'i.

Our surveys of 1401 invasive cane toads (Rhinella marina) from the Hawaiian islands of Hawai'i, O'ahu, and Maui revealed the presence of an exotic tick, Amblyomma rotundatum. Immature and adult female ticks infested three wild adult toads at a single site in the vicinity of a zoo south of Hilo, Island of Hawai'i, Hawai'i, USA. We found no tick-infested toads on O'ahu or Maui. This tick infests cane toads in their native Neotropical range, but it was excluded from Hawai'i when the original founder toads were introduced over 80 years ago. The circumstances of our discovery suggest that A. rotundatum was independently and belatedly introduced to Hawai'i with imported zoo animals, and Hawai'i now joins Florida as the second U.S. state where this tick is established.

BODY DISTRIBUTION OF HANNEMANIA SP. (ACARI: LEEUWENHOEKIIDAE) IN RHINELLA SPINULOSA, PLEURODEMA BUFONINA, AND PLEURODEMA THAUL FROM CHILE.

Hannemania larvae are parasites of amphibians in North and South America. In Chile, only one species of Hannemania has been reported from Batrachyla taeniata (banded wood frog). The objective of the study was to determine the abundance and body distribution of Hannemania among three amphibians from Antuco (Biobío Region, Chile): Pleurodema thaul (13 adults; Chile four-eyed frog), Pleurodema bufonina (5 adults; large four-eyed frog), and Rhinella spinulosa (15 adults and 16 juveniles; warty toad). Amphibians (82.75 %; n = 49) were infested with Hannemania. The infestation rate in R. spinulosa juveniles was lower than in adults (68 versus 100%, respectively; mean larval intensity: juvenile = 3.2 ± 2.5 and adult = 17.3 ± 16.3). Mean intensity of larval infestation in P. bufonina (63.2 ± 47.9) was higher than in the other two species of amphibians (R. spinulosa adult: 17.3 ± 16.3; R. spinulosa juvenile: 3.2 ± 2.5; P. thaul: 11.62 ± 7.8). There was no significant association between body size and mean intensity of infestation. The inguinal region, ventrum, and dorsal forearm region were the most parasitized. These body zones would be in direct contact with the substrate making the infestation easier for the larvae. This study represents the first record of Hannemania sp. in P. bufonina, R. spinulosa, and P. thaul in Chile.

Morphological characterization of Eustrongylides sp. larvae (Nematoda, Dioctophymatoidea) parasite of Rhinella marina (Amphibia: Bufonidae) from Eastern Amazonia.

Absctract Eustrongylides spp. nematodes have birds as final hosts and uses other vertebrates as intermediate/paratenic host (fish, amphibians and reptiles) and have zoonotic potential. In amphibians, the larvae may be located in the subcutaneous tissues, liver and mesentery, between the muscle fibres, especially in the lower limbs. Rhinella marina, which is widely observed in Brazil, has exhibited complex diversity in its helminth fauna, reflecting the unique habitat of the Amazon biome. For the first time, this study describes the morphological aspects of third-stage larvae of Eustrongylides sp. in Rhinella marina from Santa Cruz do Ararí, Marajó Archipelago, Eastern Amazonia, using light and scanning electron microscopy.

Morphological characterization of Eustrongylides sp. larvae (Nematoda, Dioctophymatoidea) parasite of Rhinella marina (Amphibia: Bufonidae) from Eastern Amazonia / Caracterização morfológica de larva de Eustrongylides sp. (Nematoda, Dioctophymatoidea) parasita de Rhinella marina (Amphibia: Bufonidae) da Amazônia Oriental Brasileira

Absctract Eustrongylides spp. nematodes have birds as final hosts and uses other vertebrates as intermediate/paratenic host (fish, amphibians and reptiles) and have zoonotic potential. In amphibians, the larvae may be located in the subcutaneous tissues, liver and mesentery, between the muscle fibres, especially in the lower limbs. Rhinella marina, which is widely observed in Brazil, has exhibited complex diversity in its helminth fauna, reflecting the unique habitat of the Amazon biome. For the first time, this study describes the morphological aspects of third-stage larvae of Eustrongylides sp. in Rhinella marina from Santa Cruz do Ararí, Marajó Archipelago, Eastern Amazonia, using light and scanning electron microscopy.

Resumo Os nematoides do gênero Eustrongylides tem as aves como seus hospedeiros definitivos e utilizam outros vertebrados como hospedeiros intermediários/paratênicos (peixes, anfíbios, répteis), além de apresentar potencial zoonótico. Em anfíbios, as larvas podem estar localizadas em tecidos subcutâneos, fígado, mesentério e entre fibras musculares de membros inferiores. Rhinella marina, anfíbio o qual é distribuído amplamente no Brasil, apresenta uma complexa diversidade em sua helmintofauna, refletindo o seu hábitat no bioma amazônico. O presente estudo descreve, pela primeira vez, os aspectos morfológicos das larvas de terceiro estágio de Eustrongylides sp. em R. marina de Santa Cruz do Arari, Arquipélago do Marajó, Amazônia Oriental Brasileira, utilizando-se microscopia de luz e microscopia eletrônica de varredura.

Rhinella marina (Amphibia: Bufonidae) Versus Rhabdias paraensis (Nematoda: Rhabdiasidae): Expanding the View on a Natural Infection.

Amphibian and reptile lungs are frequently infected with Rhabdias parasites, and this condition ultimately leads to reduced survival, performance, and growth because of granulomatous inflammation, nodule formation, and nematodal pneumonia onset. Here we investigate the histopathological features of naturally infected Rhinella marina by the lung nematode Rhabdias paraensis. A total of 10 host animals were captured in peridomiciliar areas in the eastern Brazilian Amazon, and anatomic-histological analyses were performed on both the infected and non-infected lungs of these amphibians. Helminths were usually found within the secondary and primary septa of infected lungs whereas parasites were not detected within vessels or adhering to tissues. In addition, we observed discrete erythrocytes, diapedesis foci, few granulocytes and erythrocytes in the interseptal spaces, discrete cell infiltration, and a small number of melanomacrophages, and no granulomas or cysts were observed. New aspects related to changes in tissue and helminth-host interactions are discussed for the relationship of R. paraensis × Rhi. marina from the Amazon region.

The morphology of free-living stages and immature parasites of Rhabdias paraensis (Nematoda: Rhabdiasidae), a parasite of Rhinella marina (Anura: Bufonidae) in Brazil.

Rhabdias paraensis Santos, Melo, Nascimento, Nascimento, Giese et Furtado, 2011 was described based on fully gravid worms. Further investigations on the free-living stages, immature worms and young individuals were facilitated by cultivation in the laboratory, which allowed us to add new information about the morphology and development of the species. Observations on the free-living development of R. paraensis showed that the life cycle is typical of Rhabdias, with alternation of gonochoristic and hermaphroditic generations and without homogony. Males of the free-living generation were different from those in several species of the genus studied previously. In the original description, the excretory glands and duct were absent in gravid specimens of R. paraensis, while in this study, distinct excretory glands and a duct were observed in immature and young individuals. Additionally, we recognised the separation of the buccal capsule walls into anterior and posterior portions and described the specific shapes of these portions in lateral and apical view. Studies on the morphology and development of free-living stages of Rhabdias spp. from Neotropical regions may provide additional information for species determination.

The Effects of a Nematode Lungworm (Rhabdias hylae) on its Natural and Invasive Anuran Hosts.

Biological invasions can bring both the invader and native taxa into contact with novel parasites. As cane toads ( Rhinella marina ) have spread through Australia, they have encountered lungworms (Rhabdias hylae) that occur in native frogs. Field surveys suggest that these lungworms have not host-switched to toads. In our laboratory studies, R. hylae infected cane toads as readily as it infected native frogs, but failed to reach the lungs of the novel host (i.e., were killed by the toads' immune response). Plausibly, then, R. hylae might reduce the viability both of their native hosts (frogs, that can exhibit high parasite burdens) and cane toads (that must deal with infective larvae traveling through the host body). Our laboratory trials suggest, however, that the impacts of the parasite on infected anuran hosts (both frogs and toads) were minimal, with no significant decrements to host survival, activity, growth, or locomotor performance. Ironically, the lack of impact of the parasite on its native hosts appears to be an outcome of co-evolution (frogs tolerate the lungworm), whereas the lack of impact on the novel host is due to a lack of co-evolution (toads can recognize and eliminate the lungworm).

An introduced pentastomid parasite (Raillietiella frenata) infects native cane toads (Rhinella marina) in Panama.

The pentastomid parasite, Raillietiella frenata, is native to Asia where it infects the Asian House gecko, Hemidactylus frenatus. This gecko has been widely introduced and recently R. frenata was found in introduced populations of cane toads (Rhinella marina) in Australia, indicating a host-switch from introduced geckos to toads. Here we report non-native adult R. frenata infecting the lungs of native cane toads in Panama. Eight of 64 toads were infected (median = 2.5, range = 1-80 pentastomids/toad) and pentastomid prevalence was positively associated with the number of buildings at a site, though further sampling is needed to confirm this pattern. We postulate that this pattern is likely due to a host shift of this parasite from an urban-associated introduced gecko. This is the first record of this parasite infecting cane toads in their native range, and the first instance of this parasite occurring in Central America.

Quantifying anuran microhabitat use to infer the potential for parasite transmission between invasive cane toads and two species of Australian native frogs.

Parasites that are carried by invasive species can infect native taxa, with devastating consequences. In Australia, invading cane toads (Rhinella marina) carry lungworm parasites (Rhabdias pseudosphaerocephala) that (based on previous laboratory studies) can infect native treefrogs (Litoria caerulea and L. splendida). To assess the potential of parasite transmission from the invader to the native species (and from one infected native frog to another), we used surveys and radiotelemetry to quantify anuran microhabitat use, and proximity to other anurans, in two sites in tropical Australia. Unsurprisingly, treefrogs spent much of their time off the ground (especially by day, and in undisturbed forests) but terrestrial activity was common at night (especially in anthropogenically modified habitats). Microhabitat overlap between cane toads and frogs was generally low, except at night in disturbed areas, whereas overlap between the two frog species was high. The situations of highest overlap, and hence with the greatest danger of parasite transmission, involve aggregations of frogs within crevices by day, and use of open ground by all three anuran species at night. Overall, microhabitat divergence between toads and frogs should reduce, but not eliminate, the transmission of lungworms from invasive toads to vulnerable native frogs.

Foleyellides rhinellae sp. nov. (Nematoda, Onchocercidae) a new filaria parasitizing Rhinella marina (Anura, Bufonidae) in Mexico.

A new nematode species, Foleyellides rhinellae sp. nov. (Onchocercidae), is described from specimens found in the body cavity of the cane toad, Rhinella marina (Linnaeus) (Anura, Bufonidae), in the Laguna de Coyuca, Guerrero, in the Pacific slope of Mexico. The new species differs from the other nine species of Foleyellides by infecting bufonid anurans and by the number and arrangement of caudal papillae. Other distinguishing feature of the new species is the size of the left spicule (0.16-0.23 long), the smallest recorded among the species included in the genus. Foleyellides rhinellae sp. nov. is the second known species of the genus recorded from amphibians of Mexico.

Survey of helminths, ectoparasites, and chytrid fungus of an introduced population of cane toads, Rhinella marina (Anura: Bufonidae), from Grenada, West Indies.

One hundred specimens of Rhinella marina , (Anura: Bufonidae) collected in St. George's parish, Grenada, from September 2010 to August 2011, were examined for the presence of ectoparasites and helminths. Ninety-five (95%) were parasitized by 1 or more parasite species. Nine species of parasites were found: 1 digenean, 2 acanthocephalans, 4 nematodes, 1 arthropod and 1 pentastome. The endoparasites represented 98.9% of the total number of parasite specimens collected. Grenada represents a new locality record for Mesocoelium monas, Raillietiella frenatus, Pseudoacanthacephalus sp., Aplectana sp., Physocephalus sp., Acanthacephala cystacanth, and Physalopteridae larvae. The digenean M. monas occurred with the highest prevalence of 82%, contrasting many studies of R. marina where nematodes dominate the parasite infracommunity. Female toads were found to have a significantly higher prevalence of Amblyomma dissimile than male toads. Only 2 parasites exhibited a significant difference between wet and dry season with Parapharyngodon grenadensis prevalence highest in the wet season and A. dissimile prevalence highest during the dry season. Additionally, A. dissimile was significantly more abundant during the dry season.

Seasonal dynamics of the lungworm, Rhabdias pseudosphaerocephala, in recently colonised cane toad (Rhinella marina) populations in tropical Australia.

The impact of parasites on host populations depend upon parasite prevalence and intensity. Understanding how infection dynamics change through time following a host population's initial exposure to the parasite is fundamental to host-parasite biology. We studied an invasive host (the cane toad, Rhinella marina) currently undergoing range expansion - a process through which this host's range is expanding faster than that of its lung parasites (the nematode, Rhabdias pseudosphaerocephala), such that hosts at the expanding range edge remain parasite-free for several years. It was predicted that parasite intensity and prevalence would be affected by host characteristics (e.g., size, sex), environmental conditions (e.g., seasons, habitat type), and time since parasite arrival in the newly established invading host population. Over 2,400 cane toads were sampled at 10 sites in recently established toad populations in the highly seasonal monsoonal tropics of northern Australia. The sampling spanned 14 consecutive 3 month seasons commencing in the early stages of lungworm establishment in those toad populations. Both parasite prevalence and intensity increased with host body size but were unaffected by host sex. Prevalence and intensity were highest during drier times of year and in drier habitats (i.e., sites lacking permanent waterbodies). These changes in parasite prevalence may reflect a trend for saturated soil to reduce parasite survival during the free-living infective stage, and to allow anuran hosts to disperse widely (thus reducing the transfer of directly transmitted parasites between hosts). Conversely, dry conditions induce toads to aggregate in moist dry-season refugia where conditions may be more conducive to direct transmission of infective parasitic larvae between hosts.

A new species of Mesocoelium (Digenea: Mesocoeliidae) found in Rhinella marina (Amphibia: Bufonidae) from Brazilian Amazonia.

Mesocoelium lanfrediae sp. nov. (Digenea: Mesocoeliidae) inhabits the small intestine of Rhinella marina (Amphibia: Bufonidae) and is described here, with illustrations provided by light, scanning electron microscopy and molecular approachs. M. lanfrediae sp. nov. presents the typical characteristics of the genus, but is morphometrically and morphologically different from the species described previously. The main diagnostic characteristics of M. lanfrediae sp. nov. are (i) seven pairs of regularly-distributed spherical papillae on the oral sucker, (ii) ventral sucker outlined by four pairs of papillae distributed in a uniform pattern and interspersed with numerous spines, which are larger at the posterior margin and (iii) small, rounded tegumentary papillae around the opening of the oral sucker, which are morphologically different from those of the oral sucker itself, some of which are randomly disposed in the ventrolateral tegumentary region of the anterior third of the body. Addionally, based on SSU rDNA, a phylogenetic analysis including Brachycoeliidae and Mesocoeliidae taxa available on GenBank established the close relationship between M. lanfrediae sp. nov. and Mesocoelium sp.