Anurans trophic dynamic and guild structure in tropical dry forests of the Caribbean region of Colombia.

Studies on the exploitation of trophic resources allow to establish interactions between predators and predator-prey, and this dynamic can present fluctuations over time and space. We analysed stomach contents of 19 anuran species from tropical dry forests of Colombia, quantified the overlap between species and identified anuran trophic guilds. Most of the species were generalists in diet (89.5%), some with strong prey dominance and only two species were classified as specialists. Two anurans guilds were identified according to diet structure and habitat use: "ground foraging anurans, consuming Formicidae and Isoptera" and "arboreal 'sit-and-wait' predators, primarily consuming arachnids". A considerable number of species did not clearly group in community trophic structure analysis. The level of taxonomic resolution with that preys are worked affects analysis of trophic niches segregation when analyzing regional and local patterns. Anuran species of tropical dry forest in the Colombian Caribbean display trophic resources partitioning at the level of species and/or morphospecies, as a mechanism of coexistence.

A new flesh fly species (Diptera: Sarcophagidae) parasitic on leptodactylid frogs.

Here we describe a new species of sarcophagid fly reared from larvae found feeding on three species of leptodactylid frogs collected in subtropical Corrientes Province in northeastern Argentina. Our species description is based on adult male and female external morphology and genitalia. Adult males and females of the new species were associated with certainty because all specimens studied were reared from single clutches of larvae on each of three infested frogs. Thus, adult males and females reared from each clutch were siblings that emerged almost simultaneously. The paper provides line drawings, high-resolution photographs, and SEM images to aid in identifying Lepidodexia (Notochaeta) adelina sp. nov. and to distinguish the new species from its closely related congeners. We include brief notes on the host species and on larval feeding behavior of L. (N.) adelina. This is the first and only species in the genus Lepidodexia reported to parasitize leptodactylid frogs. Further, our observations reported here are the first to fully document a completed life cycle by sarcophagid fly larvae on three different species of leptodactylid frogs and the only well-documented case of myiasis of an amphibian in Argentina.

A New Species of Cosmocerca Diesing, 1861 (Nematoda: Cosmocercidae) in Elachistocleis haroi Pereyra, Akmentins, Laufer, and Vaira, 2013 (Amphibia: Microhylidae) from South American Chaco.

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.

[Feeding of two amphibian species (Anura: Hylidae) during the low temperatures season and its relationship with energy storage in Santa Fe, Argentina]. / Alimentación de dos especies de anfibios (Anura: Hylidae) en la estaci6n de bajas temperaturas y su relación con la acumulación de energía en Santa Fe, Argentina.

Feeding of two amphibian species (Anura: Hylidae) during the low temperatures season and its relationship with energy storage in Santa Fe, Argentina. In environments with thermal and pluvial seasonality such as those of the Middle Paraná River floodplain (Province of Santa Fe, Argentina), most amphibian species reproduce during the warm season and drastically diminish their activity during winter. Even though, a few species remain active during the cold season, such as Hypsiboas pulchellus that has its reproductive peak during the autumn-winter period (and the consequent energy demand). The objective of this study was to analyze and compare the feeding and development of fat bodies during the low temperature season for H. pulchellus and Dendropsophus nanus. We analyzed entire gastrointestinal tract contents of both species (H. pulchellus = 110 specimens; D. nanus = 114 specimens) and applied an index (IRI%) that combines prey abundance, volume and frequency to describe frogs diets; we used fat bodies weights as indicators of stored energy reserves. We compared diet between species with a niche overlap index (Ojk: 0-1) and used null models to ascribe statistical significance to evaluate overlap; and we analyzed variation in empty guts proportions through months and between species. Also, using ANCOVAs we explored differences in fat bodies, number and volume of prey consumed along months, between species and sexes. The most important preys in H. pulchellus diet during the cold season were Araneae (IRI% = 34.96), Chironomidae (IRI% = 33.08), Tipulidae (IRI% = 11.44) and Gryllidae (IR1% = 7.31); while for D. nanus, Chironomidae (IR1% = 48.14), Tipulidae (IRI% = 18.41), Psychodidae (IRI% = 7.44) and Araneae (IRI% = 7.34). Diet overlap between species was elevated (Ojk=0.78) and higher than expected by chance (mean simulated indices: Ojk = 0.04; p[observed > or = expected]<0.01; p[observed < or = expected] = 1). In H. pulchellus there was a monthly variation in number of prey per gut, while in D. nanus there was a difference in fat bodies development between sexes. Fat bodies development, number of prey per gut and preys volume also varied between species. Despite diet similarity between H. pulchellus and D. nanus, each species showed a different strategy to accumulate energy and support their activity during the cold season. The low rate of gastrointestinal emptiness in H. pulchellus (< 10% in any analyzed month) together with the poor development of their fat bodies, allows us to point out that, to sustain the breeding elevated energy demands, this species continues with a high feeding rate even at the low temperatures of cold season. On the other hand, the rate of gastrointestinal emptiness of D. nanus was higher than that of H. pulchellus (May = 17.24%, July = 22.22% and August = 35.71%), while their fat bodies were well developed. Thus, D. nanus would depend more on their stored reserves to sustain the energy demands of being active during the low temperatures season and hence would reach the reproductive season in spring-summer in good body condition.

Structure of the helminth community in Dermatonotus muelleri (Anura: Microhylidae) from the driest area of the American Chaco

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.

Presence of Kalicephalus subulatus Molin, 1861 (Nematoda, Diaphanocephalidae) in Wagler's snake, Xenodon merremi from Argentina

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.

Alimentación de dos especies de anfibios (Anura: Hylidae) en la estación de bajas temperaturas y su relación con la acumulación de energía en Santa Fe, Argentina / Feeding of two amphibian species (Anura: Hylidae) during the low temperatures season and its relationship with energy storage in Santa Fe, Argentina

In environments with thermal and pluvial seasonality such as those of the Middle Paraná River floodplain (Province of Santa Fe, Argentina), most amphibian species reproduce during the warm season and drastically diminish their activity during winter. Even though, a few species remain active during the cold season, such as Hypsiboas pulchellus that has its reproductive peak during the autumn-winter period (and the consequent energy demand). The objective of this study was to analyze and compare the feeding and development of fat bodies during the low temperature season for H. pulchellus and Dendropsophus nanus. We analyzed entire gastrointestinal tract contents of both species (H. pulchellus=110 specimens; D. nanus=114 specimens) and applied an index (IRI%) that combines prey abundance, volume and frequency to describe frogs diets; we used fat bodies weights as indicators of stored energy reserves. We compared diet between species with a niche overlap index (Ojk: 0-1) and used null models to ascribe statistical significance to evaluate overlap; and we analyzed variation in empty guts proportions through months and between species. Also, using ANCOVAs we explored differences in fat bodies, number and volume of prey consumed along months, between species and sexes. The most important preys in H. pulchellus diet during the cold season were Araneae (IRI%=34.96), Chironomidae (IRI%=33.08), Tipulidae (IRI%=11.44) and Gryllidae (IRI%=7.31); while for D. nanus, Chironomidae (IRI%=48.14), Tipulidae (IRI%=18.41), Psychodidae (IRI%=7.44) and Araneae (IRI%=7.34). Diet overlap between species was elevated (Ojk=0.78) and higher than expected by chance (mean simulated indices: Ojk=0.04; p[observed≥expected]<0.01; p[observed≤expected]=1). In H. pulchellus there was a monthly variation in number of prey per gut, while in D. nanus there was a difference in fat bodies development between sexes. Fat bodies development, number of prey per gut and preys volume also varied between species. Despite diet similarity between H. pulchellus and D. nanus, each species showed a different strategy to accumulate energy and support their activity during the cold season. The low rate of gastrointestinal emptiness in H. pulchellus (<10% in any analyzed month) together with the poor development of their fat bodies, allows us to point out that, to sustain the breeding elevated energy demands, this species continues with a high feeding rate even at the low temperatures of cold season. On the other hand, the rate of gastrointestinal emptiness of D. nanus was higher than that of H. pulchellus (May=17.24%, July=22.22% and August=35.71%), while their fat bodies were well developed. Thus, D. nanus would depend more on their stored reserves to sustain the energy demands of being active during the low temperatures season and hence would reach the reproductive season in spring-summer in good body condition.

Existe escasa información sobre la alimentación de las especies de anfibios activas durante la estación fría o las estrategias de utilización de reservas lipídicas como fuente de energía durante el periodo de bajas temperaturas. Por lo tanto, se analizaron las estrategias de obtención y acumulación energética durante la estación de bajas temperaturas en un anfibio que se reproduce principalmente en otoño-invierno, Hypsiboas pulchellus (Hp), y uno que lo hace en primavera-verano, Dendropsophus nanus (Dn). Para ello se analizó la alimentación de ambas especies y se utilizó el peso de los cuerpos grasos (CG) como indicador del desarrollo de las reservas energéticas. Si bien se encontró una elevada similitud en la dieta entre las especies, esto no implicó la ausencia de diferencias en las estrategias de obtención energética entre ellas. El bajo índice de vacuidad gastrointestinal de Hp, acompañado de CG poco desarrollados, permite señalar que, para sostener la elevada demanda energética de la actividad reproductiva concentrada en el otoño-invierno, esta especie continúa alimentándose aún en temperaturas bajas. Por otro lado, el índice de vacuidad de Dn fue mayor al de Hp, mientras que sus CG se encontraron bien desarrollados, por lo que esta especie utilizaría en mayor medida sus reservas lipídicas como fuente de energía para transitar el período de bajas temperaturas y llegar en buenas condiciones a la temporada reproductiva en la próxima primavera-verano.

Diversity of amhhibians in rice fields from northeastern Argentina / Diversidad deanffibios en campos de arroz en el noreste de Argentnaa / diversidadE de anfÍbios eM campos de arroz NO nordeste da argentina

The anuran biodiversity and richness of a frog community inhabiting rice fields in northeastern Argentina was surveyed and analyzed. The samples were taken between October 2001 and June 2003. Twenty six species of amphibians were identified in five microhabitats: rice fields per se, ditches and paths, natural vegetation, aquatic vegetation and gullies. The natural vegetation was the most diverse of the microhabitats, while gullies were the poorest in species. The amphibian species of three of the microhabitats adjusted to the logarithmic range-abundance model, one to the geometric and one to the broken stick model. The data suggest that rice cropping in northeastern Argentina, if properly managed, can support a diverse anuran fauna.

Se registró y analizó la diversidad y riqueza de una comunidad de anfibios que habita campos de arroz en el nordeste de Argentina. Las muestras fueron obtenidas en el período comprendido entre octubre 2001 y junio 2003. Se identificaron 26 especies habitando cinco microhábitats: campos de arroz, zanjas y caminos, vegetación natural, vegetación acuática y barrancas. La vegetación natural fue el microhábitat más diverso mientras que las barrancas presentaron la menor cantidad de especies. El modelo de rango abundancia serie logarítmica fue el de mejor ajuste para tres de los microhábitats analizados, otro se ajustó al modelo geométrico y el restante al modelo de varilla rota. Los datos sugieren que los cultivos de arroz del nordeste argentino, podrían albergar una fauna muy diversa si están sujetos a un manejo apropiado.

Registrou-se e analisou-se a diversidade e riqueza de uma comunidade de anfíbios que habita campos de arroz no nordeste da Argentina. As amostras foram obtidas no período compreendido entre outubro de 2001 e junho de 2003. Identificaram-se 26 espécies habitando cinco microhábitats: campos de arroz, sulcos e caminhos, vegetação natural, vegetação aquática e barrancas. A vegetação natural foi o microhábitat mais diverso enquanto que as barrancas apresentaram a menor quantidade de espécies. O modelo de espécie-abundância de série logarítmica foi o de melhor ajuste para três dos microhábitats analisados, outro foi ajustou ao modelo geométrico e o último ao modelo de vara quebrada. Os dados sugerem que os cultivos de arroz do nordeste argentino poderiam abrigar uma fauna muito diversa se estão sujeitos a uma manipulação apropriada.