Estudo comparativo sobre a estrutura das comunidades de metazoários endoparasitos do lagarto Gonatodes humeralis (Guichenot, 1855) (Squamata: Sphaerodactylidae), em duas áreas com diferentes graus de impactos antrópicos no município de São Luís, Maranhão, Brasil

Abstract

In recent years, parasitological studies involving helminths infecting squamate reptiles in Brazil have significantly increased. Despite this growth, the diversity and richness of helminth species parasitizing lizards, as well as the factors structuring their parasitic communities, remain poorly understood and explored in the country, given the high potential biodiversity of both parasites and their hosts. Gonatodes humeralis (Guichenot, 1855) is a small lizard widely distributed across numerous Latin American countries. Although its behavioral, ecological, and phylogenetic aspects are well-known, amplified studies on the composition of its parasitic community are lacking in Brazil, with related studies limited to small samplings where only four species of nematodes are known to parasitize G. humeralis. The aim of this study was to comparatively evaluate the structure of the metazoan parasite community of the lizard G. humeralis in two areas with different degrees of environmental preservation in the state of Maranhão, Brazil. The first area was the Bacanga State Park, established to preserve underground water sources and surface water bodies. Despite being a conservation area, Bacanga State Park has been heavily impacted by human activities and increased urbanization in the region where it is located. The second collection area was the Itapiracó Environmental Protection Area, created to protect springs and preserve the remaining biodiversity of the Amazon domain. Hosts were manually captured through active search during October and November 2023. A total of 132 individuals were captured, with 85 from the Itapiracó Area and 47 from Bacanga State Park. The parasite community consisted of cestodes identified as Oochoristica sp., nematodes identified as Skrjabinelazia galliardi (Chabaud, 1973), and digeneans found in only two hosts in the Itapiracó Area, identified as Mesocoelium sp. The host's sex (male or female) and ontogeny (adult or juvenile) were related to weight and size (rostral-cloacal length [RCL]) of the lizards, with males and adults showing greater weight and RCL in both study areas. Location and sex, when interacting with RCL, influenced the abundance of S. galliardi, which was higher in males in the Itapiracó Area. The same variables did not influence the abundance or prevalence of cestodes or S. galliardi. Due to its presence in only one study area with very low prevalence and abundance, Mesocoelium sp. was not included in statistical analyses. Skrjabinelazia galliardi was the most dominant species overall. Additionally, we concluded that statistically, the two study areas exhibited very similar parasite communities despite differing levels of anthropogenic impact. It was apparent that host body size influenced infection rates, with larger hosts typically being older, providing more space for parasite colonization, and spending more time in the environment exposed to infections. The parasite communities showed low diversity and richness, high dominance, and no interaction among species, indicating a typical structure of communities formed by endoparasites in reptiles.