Nematodes of genus Parapharyngodon (Oxyuroidea: Pharyngodonidae) a parasite of large intestine of Osteocephalus taurinus (Anura: Hylidae) from Caxiuanã National Forest, Pará, Brazil

LOPES LEITE, BN; DOS SANTOS, JEANNIE NASCIMENTO; DOS SANTOS, ANA NUNES; GONZÁLEZ, CYNTHYA E.; DOS SANTOS, TAP; PENHA FURTADO, A; DE VASCONCELOS MELO, FRANCISCO TIAGO

Rio de Janeiro

Congreso; XXV Congreso Brasilero de Parasitología; 2017

Sociedad Brasilera de Parasitología

Osteocephalus taurinus (Steindachner, 1862) is an anuran of arboreal and nocturnal habit that belongs to the femily Hylidae mainly distributed in the Amazonian Basin, Guiana, Suriname and French Guiana. They are characterized by having a flat dorsum in females and granular dorsum in males. The dorsal coloration varies from light brown to dark brown. Some individuals have a light brown line in the center of the back, and the males have two vocal sacs laterally arranged on the head. Nematodes of the genus Parapharyngodon are amphibians and reptiles parasites, being characterized by females presenting eggs with subterminal operculum and males presenting non-pedunculated sessile papillae. There are few reports of parasitism for this host in the literature, therefore, there is a need for studies to know its helminths parasites. Thus, this work aims to describe the nematodes of the genus Parapharyngodon found in the large intestine of O. taurinus. A helminthological expedition was carried out between 2014 and 2015, where eight individuals of O. taurinus were collected in the National Forest (FLONA), region of Caxiuanã, and in the surrounding area of Ferreira Pena Science Station, Melgaço, Pará, Brazil. After the collect, the anurans were anesthetized, weighed and necropsied in the Scientific Laboratory of the Station. The helminths were collected, rinsed in saline solution, fixed in 70% alcohol, clarified in Aman lactophenol and observed in Olympus BX41 light microscope for morphological and morphometric analysis. For Scanning Electron Microscopy analysis, some specimens were dehydrated to the critical point of Co2, metallized with a thin layer of gold-paladium, mounted on metallic supports and analyzed in VEGA2 Tescan Electronic Microscope of the Federal Rural University of Amazônia. The nematodes have a fusiform and robust body, cuticles with evident transverse striations throughout the body, except for the caudal filament, triangular oral opening surrounded by three bilobed lips, oxyuroid esophagus, nerve ring located in the anterior portion of the esophagus and post-bulbar excretory pore. The males have an evident lateral wing, a slightly sclerotized spike tail and genital cone; also presents a pair of ad cloacal non-pedunculated sessile papillae, one pair on the upper lip of the cloaca, and a single caudal papilla. The females are prodelphic, devoid of lateral wing, vulva located in the median region of the body, eggs with subterminal operculum and ovary surrounding the intestine. Based on the morphological data found in the present work, and according to the correlated literature, these nematodes belong to the genus Parapharyngodon. To date, this genus have six species described from neotropical region parasitizing amphibians and reptiles, and the species of the present study differs morphologically from the species already described, and may be a new species. Therefore, dditional studies on the morphometry, morphology and molecular biology analyzes still necessary for the identification and formal description of this new species.