Occurrence of Chandleronema longigutturata (Nematoda: Acuariidae) in Procyon cancrivorus in the Neotropical region

Procyon cancrivorus is a wild animal that is found from Central America to Uruguay and northeastern Argentina. It is one of the least studied carnivore species in Brazil. For the purpose of identifying helminths that parasitize P. cancrivorus, individuals of this species that had been run over and killed by motor vehicles were collected from highways in the southern part of the state of Rio Grande do Sul. At necropsy, their organs, along with organ contents and mucous membranes, were examined for parasite collection. The nematodes found in the stomachs of these Procyonidae were cleared with lactophenol and Chandleronema longigutturata was identified. This report provides the first record of occurrences of C. longigutturata in the Neotropical region and its parasitism in P. cancrivorus.

Palavras-chave: Procyon cancrivorus, Chandleronema longigutturata, Nematoda, neotropical. Procyon cancrivorus, also known as the raccoon or crab-eating raccoon, belongs to the Procyonidae family and is found from Central America to Uruguay and northeastern Argentina. It occurs in all Brazilian biomes (REIS et al., 2006), and is one of the least studied carnivore species in this country (MORATO et al., 2004). In Brazil, it is popularly called "mão pelada" (bare paws) due to its furless paws (CAMERA & MURTA, 2003, apud PEREIRA et al., 2010. Wild animals are reservoirs for various parasites. Studies on overall parasite fauna and biodiversity are based mainly on the importance of parasites as disease agents affecting ecosystems and the health of natural and domestic environments (BROOKS & HOBERG, 2001).
Environmental problems affect the ecological balance and end up bringing wild animals closer to humans and pets. This closer contact allows dissemination of infectious and parasitic agents into new hosts and environments, thereby establishing new relationships that affect the disease transmission chain. As a result of these negative interactions, zoonoses of large epidemic extent and greater geographical spread of these agents may occur (BARTLETT & JUDGE, 1997).
Analyses on parasite diversity among wild animals can be a good indicator of ecosystem health, since this diversity reflects the phylogeny and conditions that enable symbiosis between parasites and hosts and therefore shows the evolutionary pressure on both of them (CHAI et al., 2005).
Nine of P. cancrivorus specimens were collected from highways in the southern part of the state of Rio Grande do Sul, where they had been run over and killed by motor vehicles (Authorization No. 38913-1 SISBIO/RS; EAEC/UFPel-07/05/2009). The animals collected were placed in individual plastic bags and were transported in coolers to the Laboratory of Wild-Animal Parasitology of the Federal University of Pelotas, where they were necropsied.
Their organs were then removed, opened and washed in a 106-micrometer mesh sieve. Each organ was examined under a stereomicroscope, and its contents were washed in order to collect any helminths that were present. The nematodes found were fixed in ethanol (70 °GL), clarified with Aman's lactophenol for identification in accordance with Little & Ali (1980) and then photographed under an Olympus BX41 microscope with an adapted camera system.
Out of the nine P. cancrivorus examined, six were parasitized by Chandleronema longigutturata, which was found in their stomachs. Among these parasites, 33 were females and four were males, and larval forms were also observed. Their measurements are shown in Table 1.
The genera of the subfamily Acuariidae are differentiated mainly in relation to their cuticular base and structures such as cordons, thorns, papillae, etc. (CHABAUD, 1975). Nematodes of the Acuariidae family mainly parasitize birds, but species other than C. longigutturata have been reported in mammals, such as Paracuaria soricis (JANÇEV, 1972) and Stammerinema soricis (TINER, 1951) in soricines; Synhimanthus australiensis (BEVERIDGE & BARKER, 1975) and Antechiniella suffodiax (BEVERIDGE & BARKER, 1975) in rodents and marsupials; and Skrjabinoclava thapari (TEIXEIRA DE FREITAS, 1953apud VICENTE et al., 1997 in P. cancrivorus in Brazil. Chandler (1942) apud Chandler (1980) reported that nematodes found in the stomachs of raccoons presented morphological characteristics similar to those of the genus Synhimanthus. However, Little & Ali (1980) redescribed the parasites, classifying them as belonging to the genus Chandleronema because of their cephalic cords characteristics and their cylindrical and exceptionally long pharynx.
The characteristics of these nematodes found in the stomach of P. cancrivorus included short, delicate, recurrent and anastomosing cephalic cordons (Figures 1b and 1c.); a small cephalic dilation and a long pharynx ( Figure 1b); tricuspid papillae (Figures 1a and 1d); spicule morphology ( Figure 1e); four pairs of pre-cloacal papillae and five pairs in the post-cloacal region; and eggs conforming with the description of C. longigutturata by Little & Ali (1980). Birds and the procyonid P. cancrivorus have similar diets (fish, crustaceans, snails, seeds, etc.) thus enabling both of them, albeit differently, to host the same parasites.