High prevalence of trombiculid mite (Hannemania spp.) infestations in a microendemic and endangered frog from the southern temperate forest in Chile

The Contulmo Ground Frog (Eupsophus contulmoensis) and Darwin’s frog (Rhinoderma darwinii), are threatened endemic frogs from Chile. Hannemania (Acari: Trombiculidae: Leeuwenhoekiinae) are endoparasitic chiggers mites of... [ view full abstract ]

The Contulmo Ground Frog (Eupsophus contulmoensis) and Darwin’s frog (Rhinoderma darwinii), are threatened endemic frogs from Chile. Hannemania (Acari: Trombiculidae: Leeuwenhoekiinae) are endoparasitic chiggers mites of amphibians, occurring across all American continent. The aims of this study was to (I) report for the first time the parasitism of Contulmo Ground Frog by Hannemania chigger, (II) determine the infestation prevalence and (III) and describe the skin lesion in Contulmo Ground Frog. Forty two E. contulmoensis and 122 R. darwinii were captured in two remnants of native temperate austral forest located in Contulmo National Monument (38° 1'2.76"S 73°10'19.50"O), south-central Chile. After in situ examination the animals were released in the exact capture place. One individual was found dead and was used for mites identification after mounted in Hoyer`s liquid and histopathological analysis by Hematoxilin-Eosin staining. Of all 42 E. contulmoensis, 27 (64.3%) were infested externally with white cyst in different regions of the body, especially on fore and hind limbs with one mite being immersed in each cyst. Cyst prevalence was 74% in E. contulmoensis adults and 46.7% in juveniles. No apparent cyst were found in R. darwinii. Histological sections of the infected skin containing the cyst shows that the entire capsule is located within stratum spongiosum of the dermis. In the area of the skin containing the encapsulated mites, show signs of cell proliferation. Histological findings were consistent with those described for Hannemania. Mites were identified as Hannemania based on their morphological characteristic using identification keys. Although we did not know the relevance of this parasite in the conservation of this species, is important to improve the knowledge of parasitic fauna of threatened species to understand host-parasite interaction. The present report constitutes a new record of an endangered endemic anuran species being parasitized by Hannemania sp. in Chile.