Abstract
The digenetic trematode Canaania obesa Travassos, 1944 (Dicrocoeliidae) was described as a parasite of the bile ducts of the rodent Akodon cursor Winge, 1887 (Cricetidae) collected in Santa Teresa, state of Espírito Santo, Brazil. In the present study, we report the occurrence of C. obesa infecting three additional sigmodontinae rodent species: Akodon montensis Thomas, 1913; Oligoryzomys nigripes Olfers, 1818 and Nectomys squamipes Brants, 1827, from three municipalities situated at Serra dos Órgãos, Rio de Janeiro, Brazil. Scanning electron microscopy showed that this helminth has a leaf-like shape with conical extremities and the ventral mid body protrudes at the acetabulum level. The microtopography of the tegument shows a heterogeneous surface with smooth or wrinkled areas and several randomly distributed papillae. The cirrus is located just posterior to the oral sucker and is covered by smooth tegument without spines or papillae. The excretory pore is subterminal. The eggs are elliptic and operculate at one of the extremities. The present study adds new taxonomic characters to C. obesa. The municipalities of Nova Friburgo, Teresópolis and Sumidouro are new geographical areas of distribution, and A. montensis, O. nigripes and N. squamipes are new host records for C. obesa.
Highlights
The Atlantic Rainforest ecosystem, one of the world’s biodiversity (MYERS et al 2000) hotspots, has been reduced to seven percent of its original size by anthropogenic activities
We report the occurrence of C. obesa infecting three additional sigmodontinae rodent species: Akodon montensis Thomas, 1913; Oligoryzomys nigripes Olfers, 1818 and Nectomys squamipes Brants, 1827, from three municipalities situated at Serra dos Órgãos, Rio de Janeiro, Brazil
Scanning electron microscopy showed that this helminth has a leaflike shape with conical extremities and the ventral mid body protrudes at the acetabulum level
Summary
Rodents were captured in three municipalities of the state of Rio de Janeiro, Brazil: 1) Nova Friburgo (22°16’55”S, 42°31’ 52”W) comprising eleven localities (Baixada Nova Friburgo, Campo do Coelho, Cardinas, Conquista, Córrego Grande, Floresta, Rio Grande, Salinas, Santa Cruz, São Lourenço and Três Cachoeiras); 2) Teresópolis (22°26’12”S, 42°58’42” W) with six localities (Bonsucesso, Fazenda Alpina, Mottas, Santa Rosa, Venda Nova and Vieira); and 3) Sumidouro (22°02”46”S, 42°41’21”W) with three localities (Campinas, Dona Mariana and São Bento). The following species were identified: A. cursor, A. montensis and A. serrensis. In the present study Akodon spp. represents rodents with an inconclusive karyotype. Other rodents species studied were identified using morphological characters. Specimens were euthanized by CO2 inhalation and necropsied for worm recovery. Their digestive system was immediately opened in a Petri dish filled with a physiological saline solution (NaCl 0.9%) at room temperature. 317 individuals were identified as Akodon spp., 423 were O. nigripes and 63 corresponded to N. squamipes. The majority of infected rodents were from localities in Teresópolis and Nova Friburgo (Tab. I). The prevalence of C. obesa was 23.3% for Akodon spp., 0.47% for O. nigripes and 1.58% for N. squamipes. Rodents in all localities in Nova Friburgo and Teresopólis were infected with C. obesa. The highest prevalences of the parasite were observed in A. cursor and A. montensis com-
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