A New Species of Molinema (nematoda: Onchocercidae) in Bolivian Rodents and Emended Description of Litomosoides

We report the distribution of 2 species of filarioid nematodes occurring in different hosts in the central region of South America. Molinema boliviensis n. sp. was recorded as a parasite of sigmodontine and echymyid rodents in Bolivia, and Litomosoides esslingeri was recorded in sigmodontine and ctenomyid rodents from Bolivia and Argentina. Molinema boliviensis n. sp. shares several similarities with other species reported in spiny rats; however, it can be easily differentiated by the presence of a flat anterior end, gradually tapering lappets and a tubercle present in posterior end, a short, uniform buccal capsule, an oval-shaped vagina vera, and a ratio of spicules of 1:1.44. An account for the morphological variability of L. esslingeri is presented that allows the identification of the buccal capsule, the tail tip in females, and the shape of spicules as reliable diagnostic traits. A complete set of head papillae is also described. The finding of these parasites in phylogenetically unrelated hosts suggests that host capture may be a frequent phenomenon in these filarioids. Researchers should focus efforts in surveying mammals within the same ecological guild to understand the distribution and host specificity of these nematodes. From 1984–2000, the American Museum of Natural History (AMNH), the Museum of Southwestern Biology (MSB), the Bolivian National Museum of Natural History in La Paz, and the Harold W. Manter Laboratory of Parasitology (HWML) mounted joint collecting expeditions throughout Bolivia to survey and inventory sylvatic mammals and their parasites. Within the geopolitical boundaries of Bolivia, more than 327 species of mammals have been documented, with about 5% being endemic (Anderson, 1997). At the present time, around 140 species of rodents are known to occur in Bolivia, some of them only recently described (Salazar et al., 1994; Anderson, 1997; Anderson and Yates, 2000; Gardner et al., 2012). While the mammal fauna of the country is fairly well known, the data on the parasites are still lagging due to the paucity of workers in this area. Members ofMolinema Freitas and Lent, 1939 and Litomosoides Chandler, 1931 (Nemata: Onchocercinae) are known exclusively from the New World (Guerrero and Bain, 2001). Representatives of both genera have been reported from echimyid, ctenomyid (Hystricomorpha), and murid (Myomorpha) rodents in South America and from castorids in North America. At the present time, 12 species of Molinema are known and most of these parasites use mosquitoes as vectors (Bain, 1974); adults may be found in the body cavity of hystricognath rodents (11 species) and beavers (1 species) (Freitas and Lent, 1939; Anderson, 1953; Esslinger, 1974; Guerrero and Bain, 2001). To our knowledge, there is no record for any species of Molinema in Bolivia. There are 41 species included in Litomosoides, all recorded from the thoracic and abdominal cavities of sigmodontine and ctenomyid rodents, bats, and marsupials (Caballero, 1947; Esslinger, 1973; Bain et al., 1989; Brant and Gardner, 1997; Notarnicola et al., 2000). Species of Litomosoides use mites as intermediate hosts (Bain et al., 1980). In Bolivia, they have been recorded in tuco-tucos (Hystricognathi: Ctenomyidae) and in phyllostomid and vepertilionid bats (Brant and Gardner, 1997; 2000; Notarnicola et al., 2010). As part of our investigations on Bolivian parasite biodiversity, we herein describe a new species of Molinema parasitizing sigmodontine and echymyid rodents (Holochilus and Proechimys, respectively) and record for the first time Litomosoides esslingeri Bain, Petit and Diagne, 1989 for Bolivia and Argentina. We also provide some additional data on the morphological variability of L. esslingeri based on observations of the type specimens and material from the present study. MATERIALS AND METHODS Rodents collected in the field were processed following the guidelines for the use of wild mammals in research of the American Society of Mammalogists (Sikes and Gannon, 2011). Nematodes were collected and preserved following Gardner (1996) and Gardner and Jiménez (2009). Filarioids were placed directly into either 70% ethanol, 95% ethanol, or 10% formalin; some were killed and straightened in glacial acetic acid and stored in 70% ethanol. All filarioids were transported in those solutions to the Harold W. Manter Laboratory (HWML), Lincoln, Nebraska, and stored until further examination. For study of morphological characters, specimens were cleared in lactophenol and examined using a Zeiss Ultraphot or Zeiss Axiophot digital microscope (Zeiss, Oberkochen, Germany). To examine the oral papillae, the apical portion was excised from a specimen and used to prepare an en face view. The lateral cuticular internal ridge was used to identify lateral fields and the Y-shaped section of the lumen of the esophagus was used to identify the dorsal side. The uterus of 1 female was dissected to extract microfilariae. Illustrations were made with the aid of a drawing tube. Measurements are presented as follows: holotype male; paratypes males, allotype female, and paratypes females. If more than 3 specimens were examined, mean values and standard deviations are presented with ranges in parentheses; measurements from 2 specimens are separated by semicolons. Measurements are given in micrometers unless otherwise stated. Prevalence and mean intensity of infection are also provided for each species. Specimens were deposited in the HWML (Division of Parasitology, University of Nebraska State Museum). We choose the sigmodontine rodent Holochilus sciureus Wagner, 1842 as the type host for the description of the new species of Molinema because the material included 2 males and 1 female that were well preserved. One specimen of Proechimys contained a female and a male, but they were not well preserved; the remaining hosts contained either females or males. Specimens of L. esslingeri (originally identified as Litomosoides carinii) fromMelanomys caliginosus (Tomes, 1860) from Yumbo, Valle del Cauca, Colombia, were requested from the United States National Museum, Parasite Collection (Beltsville, Maryland). Material examined included 3 males, 3 females (USNM 72391), and a slide with microfilaria from blood (USNM 72392). Other acronyms used throughout the text include: AMNH: American Museum of Natural History, New York, New York; CML: Colección Miguel Lillo, San Miguel de Tucumán, Argentina; Received 5 December 2011; revised 3 June 2012; accepted 8 June 2012. * Department of Zoology, Southern Illinois University, Carbondale, Illinois 62901-6501. † The Harold W. Manter Laboratory of Parasitology, University of Nebraska–Lincoln, Lincoln, Nebraska 68588-0547. DOI: 10.1645/GE-3059.1 J. Parasitol., 98(6), 2012, pp. 1200–1208 American Society of Parasitologists 2012