RESUMO
PURPOSE: Cosmocercids are common nematodes that parasitize the digestive tract and lungs of amphibians and reptiles around the world. They are commonly found in leptodactylid and bufonid anurans in South America, primarily in Brazil and Argentina. This paper describes a new species of genus Cosmocerca based on specimens collected in a microhylid from the Dry Chaco ecoregion. METHODS: A total of 18 specimens of Elachistocleis haroi were collected in October 2011 in Chaco province and in December 2021 and March 2022 in Formosa province, Argentina, both areas of the Dry Chaco ecoregion. The morphology of the nematodes was studied in detail using light microscopy and scanning electron microscopy. RESULTS: One hundred and fifty-one nematodes were collected from the large intestines of E. haroi. Based on the morphology of the caudal papillae (rosette papillae and plectanes), the presence of two spicules and the absence of caudal alae in males, and the presence of two prodelphic ovaries in females, these specimens were allocated to the genus Cosmocerca. However, they presented unique characteristics that differentiate them from all known species. Cosmocerca wichiorum sp. nov. is similar to C. archeyi, C. australis, C. sardiniae, C. zugi, and C. leytensis by having four pairs of plectanes, but can be easily distinguished from all of them by the type, number, and arrangement of the precloacal (non-plectanes), adcloacal and postcloacal papillae, by the length of the spicules and by its different zoogeographical distribution. CONCLUSION: This is the 14th species of the genus Cosmocerca described in South America and the first one for the microhylid E. haroi from the Dry Chaco ecoregion.
Assuntos
Microscopia Eletrônica de Varredura , Animais , Masculino , Feminino , Argentina , Microscopia Eletrônica de Varredura/veterinária , Anuros/parasitologia , Anfíbios/parasitologia , Intestino Grosso/parasitologiaRESUMO
The present study describes the helminth community collected from juveniles of Dermatonotus muelleri (Anura: Microhylidae) from the Chaco Seco Ecoregion. Helminths were found in 80.0% of specimens examined (n = 16). The helminth community of this microhylid presented very low species richness; a total of 1,339 specimens belonging four helminth species were found; three adult nematodes, Aplectana hylambatis, Cosmocerca podicipinus and Parapharyngodon sp., and an adult cestode, Ophiotaenia sp. Parasites were found in the large and small intestines. Maximum helminth richness was 2 species per infected frog. The nematode A. hylambatis presented the highest prevalence and was the most abundant (d = 0.97) indicating that it is the dominant species in the community (I = 63.0). Host snout-vent length did not influence the intensity of infection or the richness of helminth species at the community component level. Two species showed significant co-variation (A. hylambatis and Parapharyngodon sp.). The high prevalence of infection and number of parasites found for A. hylambatis could be related to the characteristics of their life cycles; the possession of the infective stage (L3) protected inside the egg membrane would have benefits against extreme drought in the area in which the study was conducted. The studies of helminths in the Chaco Seco Ecoregion, an area seriously threatened in terms of its biodiversity, are incipient. This is the second study that has been carried out to determine the structure of the parasite community in amphibians of this ecoregion.
Assuntos
Anuros , Biodiversidade , Helmintíase Animal , Helmintos , Nematoides , Animais , Anuros/parasitologia , Clima Desértico , Helmintíase Animal/epidemiologia , Helmintíase Animal/parasitologia , Helmintos/classificação , Nematoides/classificação , Prevalência , Estados UnidosRESUMO
Aplectana hylambatis is a nematode with a wide geographic distribution and low host specificity. In spite of numerous reports, until this moment, the morphological variations between different hosts and localities have not been studied. We studied 401 specimens collected from five host species from seven localities in Argentina, and examined the following morphological characters: mamelon-like cuticular protuberances anterior to the vulva, structure of the gubernaculum and the spicules, number and arrangement of caudal papillae, and the measurements of twelve characters in females and eleven characters in males. The results showed that mamelon-like protuberances and caudal papillae varied in number and arrangement between different hosts and localities. The metrical study revealed that five characters in males and six in females contributed to variability; nine characters showed significant differences between host species and localities. Specimens of A. hylambatis collected from R. arenarum formed a group clearly differentiated from the rest of the specimens. The results from this study highlight the importance of examining as many specimens as possible from different host samples and from several localities to cover the intraspecific variations.
Assuntos
Anuros/parasitologia , Nematoides/anatomia & histologia , Nematoides/classificação , Animais , Anuros/classificação , Argentina , Feminino , Geografia , Interações Hospedeiro-Parasita , MasculinoRESUMO
The goal of the present study was to analyze the metacercariae found in adult amphibians collected in the Argentinean Chaco region. A total of 194 frogs, Leptodactylus chaquensis, Leptodactylus latinasus, and Lepidobatrachus laevis was examined for digeneans. Three different larval trematodes of the genus Strigea (Digenea, Strigeidae) were found infecting the liver, mesentery, body cavity, and muscle of frogs. These metacercariae are described and illustrated for the first time and provide new information on the composition of metacercariae in amphibians, thus contributing to the knowledge of larval trematodes biodiversity in the Neotropical region. We also present new information on the morphology and morphometry of strigeid metacercariae.
Assuntos
Anuros/parasitologia , Metacercárias/anatomia & histologia , Trematódeos/anatomia & histologia , Animais , Argentina , Especificidade da EspécieRESUMO
This is the first record of the nematode parasite Kalicephalus subulatus (Strongylida, Diaphanocephalidae) in Wagler's snakes, Xenodon merremi (Squamata, Colubridae), collected in Corrientes, Argentina. The species was observed using light and scanning electron microscope (SEM) and compared to previous studies from Tropical America. As for the metric characters, the specimens collected in Argentina are smaller than all of those found so far in other hosts. However, despite the differences in the measurements, some characters such as the dorsal lobe type III and the amphidelphic uterus allow its specific identification. Previously, this genus was found in X. merremi from Argentina but the absence of males precluded their specific identification.
Assuntos
Serpentes , Estrongilídios , Animais , Argentina , Feminino , Microscopia Eletrônica de Varredura , Serpentes/parasitologia , Especificidade da Espécie , Estrongilídios/anatomia & histologia , Estrongilídios/fisiologia , Estrongilídios/ultraestruturaRESUMO
Here we describe a new cosmocercid nematode, Aplectana nebulosa sp. nov., from the small and large intestines of Pleurodema nebulosum (Anura: Leptodactylidae), from the Monte desert of San Juan, Argentina. The new species belongs to the Aplectana group that possesses a gubernaculum and unpaired adcloacal papilla anteriorly to cloaca. It resembles A. membranosa, A. paraelenae and A. travassosi by the presence of four adcloacal papillae, but differs from those species by the following characters: number and arrangement of precloacal papillae; number and arrangement of postcloacal papillae; shape and size of spicules and gubernaculum, and by the presence of lateral alae in caudal region of males. The description of the new species is based on light microscopy and scanning electron microscopy (SEM) and we also provide a key to Neotropical species of Aplectana.
Assuntos
Nematoides , Animais , Anuros , Argentina , Ascaridídios , Masculino , ParasitosRESUMO
This is the first record of the nematode parasite Schulzia travassosi (Trichostrongylina, Molineidae) in two Argentinean amphibians, Leptodactylus bufonius and Rhinella major, collected in two localities of the Chaco region, Las Lomitas (Formosa Province) and Taco Pozo (Chaco Province). The species was observed using light and scanning electron microscopy (SEM) and compared with previous studies of Paraguayan specimens. Regarding metric characters, the measurements found in Argentinean specimens generally did not differ from those of Paraguayan specimens; some differences were observed in the total length of males and females (some longer and some shorter than Paraguayan specimens), length of the oesophagus (in almost all specimens shorter than in Paraguayan ones) and position of the vulva (nearer to posterior end in Argentinean specimens). The branches and sphincter of ovejector are slightly longer than in Paraguayan female specimens. In males, ray 4 is almost the same length as rays 2, 3 and 5, 6. Cephalic end, cephalic vesicle, synlophe and vulvar depression were viewed under SEM. Schulzia melanostictusi Chopra, Shing and Kumar, 1986 is reassigned as Oswaldocruzia melanostictusi (Chopra, Shing and Kumar, 1986) nov. comb.
Assuntos
Anuros/parasitologia , Bufonidae/parasitologia , Nematoides/classificação , Nematoides/isolamento & purificação , Infecções por Nematoides/veterinária , Estruturas Animais/anatomia & histologia , Animais , Argentina , Feminino , Masculino , Microscopia , Nematoides/anatomia & histologia , Infecções por Nematoides/parasitologiaRESUMO
The goal of this study was to evaluate the relative influence of terrestrial habits, season, and host body size on the species richness and abundance of helminth parasites in the toad Melanophryniscus klappenbachi, for which a greater abundance of nematode parasites was expected. A total of 90 toads were collected in the Chaco Province, Argentina. The helminth community found in infected toads included 17 taxa and was dominated particularly by larval parasites. Contrary to our expectations, nematode species showed lower values of infection parameters. Infected toads harbored a maximum of seven species, and the mean helminth richness was 3.16 ± 1.66 species per infected toads. Season played a significant effect on determining the species richness and abundance of the parasite infracommunity. Similarly, the prevalence of infection of several helminth species (8/47%) varied greatly over time. Host body size was the main factor in determining the infrapopulation structure of helminth parasites. Species richness was significantly and negatively correlated with host body size. Strong associations were observed mainly between larvae of some species. The transmission strategies of parasites suggest that this bufonid acquires infections through direct contact with larval parasites from aquatic and terrestrial habitats and by ingestion of infective larvae. The characteristic of the host tegument, such as the presence of alkaloids, could significantly contribute to the low occurrence of infection by skin-penetrating nematodes. Results also showed that diets and mobility of the host and the local microhabitat conditions play an important role in parasitic infections of toads.
Assuntos
Bufonidae/parasitologia , Helmintíase Animal/parasitologia , Helmintos/isolamento & purificação , Interações Hospedeiro-Parasita , Animais , Argentina , Tamanho Corporal , Ecossistema , Feminino , Helmintíase Animal/transmissão , Helmintos/fisiologia , Masculino , Estações do AnoRESUMO
Here, we describe a new kathlaniid nematode, Falcaustra sanjuanensis sp. nov., from the large intestine of Odontophrynus cf. barrioi (Anura: Cycloramphidae), from San Juan Province, Argentina. The new species belongs to the Falcaustra group that possesses a pseudosucker. It resembles F. andrias in the distribution pattern of caudal papillae (six precloacal, four adcloacal, 12 postcloacal, one unpaired median anterior to the cloaca) but differs from F. andrias in the following characters: the longer size of males and females (11.17-13.45 mm and 10.1-15.5 mm, respectively); the longer size and form of the gubernaculum (0.17-0.23 mm, triangular form); the arrangement of postcloacal papillae (three pairs on the ventral side, two pairs on the lateral side, one pair on the subventral side) and unpaired papilla anterior to the cloaca located on the protuberance. The species description is based on light microscopy and scanning electron microscopy (SEM). Falcaustra sanjuanensis sp. nov. represents the 12th Neotropical species assigned to the genus. Also, we added a key to Neotropical species of Falcaustra.