Ecologia de helmintos, dieta e ecomorfologia das serpentes Sibynomorphus neuwiedi (Ihering, 1911) e Sibynomorphus mikanii (Schlegel, 1837) (Squamata, Dipsadidae) de Minas Gerais, Brasil

Abstract

Sibynomorphus neuwiedi and Sibynomorphus mikanii are small sized snakes, known as sleepy snakes, nocturnal, non-venomous and snail eaters. Both occurs in Mata Atlânica forests and impacted environments, however S. mikanii is more frequently found in Cerrado. Studies about parasitology, biology, ecology and morphology of both species are scarce. The goals of the present study where to analize ecology of helminths, the diet and ecomorphology of the snakes S. neuwiedi and S. mikanii from Minas Gerais, Brazil, register the helminths presentes in their preys, verify the effects of seazonality and gender, reproductive state, size and body mass of these snakes, so as the size of parasitized organs, on their helminths, and verify the ecological, phylogenetic and sexual effects at morphometric variation. The 39 analyzed individuals of S. neuwiedi and the 49 specimens of S. mikanii from the Herpetological Collection of the UFJF – Reptiles have had measured their length and width of head, length between eyes, rostrum-cloacal length, tail and total, and body mass. Subsequently where necropsied, sexed and analyzed the maturity, the body cavity, organs and digestive contents searched in search of helminths and preys. Parasitized organs were measured. It were colected 30 specimens of snails from Veronicellidae family, euthanasia was realized and the animal fixed, conserved and, added to the specimens found in snakes stomach, these were dissected and examined to identification and pursuit of helminths. The helminths found in the snakes and in molluscs were washed, fixed, conserved, quantified, identified and photographed. It was realized morphometry of trematodes and nematodes. The metazoans parasites communities of the snakes where composed only by endoparasites from helminths group and presents low richness and diversity, distribution patttern assembled, isolacionist profile, specificity to infection sites and predominance of only one parasite taxon by infracommunity. The prevalences were average. Both species of snakes were parasitized by two taxa of trematodes, while S. neuwiedi presented also three taxa of nematodes and S. mikanii, four (two in common amongst these snakes). The prevailing parasites taxa were Rhabdias sp. and Strongyluris sp. in both species of snakes, and Mesocoelium sibynomorphi in S. neuwiedi, do not presenting the size of this last helminth in this snake relation of intensity-dependency. The snakes presented similar diet: molluscs from species of Veronicellidae family, being registered the prey-species Sarasinula linguaeformis in S. neuwiedi and Latipes erinaceus and Sarasinula sp. in S. mikanii. Larval forms from the nematode Strongyluris sp. was the common helmint between these snakes and their prey. The seazonality variation, gender, reproductive state, size and body mass of S. neuwiedi and S. mikanii, and the size of parasitized organs, did not influenced the helminth communities of these snakes. These species did not present sexual dimorphism. The habitat did not influence the morphology these snakes, while the phylogeny influenced the morphology of adult females, what did not occurred in young females and male.