Metazoan endoparasites of Erythrolamprus poecilogyrus caesius (Cope, 1862) (Serpentes: Dipsadidae) in South American Chaco: Structural attributes at different organization levels

In this study, the structure of metazoan endoparasites infracommunities and component community in Erythrolamprus poecilogyrus caesius (Cope, 1862) (Serpentes: Dipsadidae) is presented. From 21 specimens (15 females; 6 males) collected between February 2017 and March 2022 at Ingeniero Juárez, Formosa, Argentina, 90.5% of individuals surveyed (n= 19) were infected with at least one species of metazoan endoparasite. Nine hundred sixty specimens were collected (117 adults; 843 larvae), from 11 taxa. Kalicephalus appendiculatus (Nematoda), Raillietiella furcocerca (Pentastomida), Ophiotaenia joanae, Catadiscus uruguayensis, Opisthogonimus lecithonotus (Platyhelminthes) were found as adults. Larvae identified were Oligacanthorhynchus sp. (Acanthocephala), Physaloptera sp. (Nematoda), Strigea spp. and Alaria sp. (Digenea). Digenea was the richest group (S= 6). Adults were collected in intestines, trachea and esophagus, while larvae were found in mesenteries and body cavity. Ophiotaenia joanae was the most prevalent species (38.1%) and K. appendiculatus had the highest mean abundance (3.7). Considering larvae, Strigea spp. were dominant and Oligacanthorhynchus sp. was subdominant. Between pairs of metazoans, positive and negative covariations were obtained. In general, intensity of metazoan taxa had positive correlation to host weight and body condition but had negative relationships with snout-vent length. Mean infracommunity richness (including larvae and adults) was 4.35 ± 1.27 taxa/host. Richness and diversity were higher in larval infracommunities than those composed by adults. This is the first ecological study of endoparasites in snakes from Argentina. New reports to parasite biodiversity in Dry Chaco were added, also, information about habitat use, diet, and position in trophic webs of host was generated.