Graciela T. Navone

Arthropod and filarioid parasites associated with wild rodents in the northeast marshes of Buenos Aires, Argentina.

During 1995, 16 species of arthropods and 2 species of filarioids, totaling 1 287 specimens were collected from 64 wild rodents captured in the Hudson Natural Reserve, Buenos Aires, Argentina. Infestation parameters and indexes were analyzed. Host specific richness was S = 6, diversity H = 1.48, and relative density RDI = 40%. High values of parasite species richness and diversity were found on Oligoryzomys delticola (S = 9; H = 1.40), Oxymycterus rufus (S = 9; H = 1.37), and Oligoryzomys flavescens (S = 9; H = 1.28), followed by Scapteromys aquaticus (S = 6; H = 0.17), and Akodon azarae (S = 4; H = 1.20). Deltamys kempi was infested only by Androlaelaps rotundus. O. delticola and O. flavescens showed the highest similarity index (O = 74.19%), followed by O. flavescens with S. aquaticus, as a result of historical processes and shared microhabitats. Considering arthropods-filarioids associations, significant affinity was observed in Litomosoides bonaerensis with Hoplopleura travassosi, Laelaps paulistanensis, and Gigantolaelaps wolffsohni.

FURTHER STUDY OF CONTRACAECUM PELAGICUM (NEMATODA: ANISAKIDAE) IN SPHENISCUS MAGELLANICUS (AVES: SPHENISCIDAE) FROM ARGENTINEAN COASTS

The anisakid species Contracaecum pelagicum Johnston and Mawson, 1942, is reported for first time at 2 different sites on the Argentine coast (Península Valdés, 42°04′S, 63°38′W and Mar del Plata, 38°05′S, 57°38′W), parasitizing the Magellanic penguin, Spheniscus magellanicus Foster. Morphometric analysis and further studies of adult specimens of C. pelagicum were done using light and scanning electron microscopy. The presence of bifurcated interlabia differentiates the present species from most others in the genus, except (1) from Contracaecum travassosi, which possesses higher interlabia and longer spicules, and a blunt, more constrained tail; (2) from Contracaecum rudolphii, which has longer spicules, blunter spicule tips, postparacloacal papillae with oblique disposition, and a blunter constrained tail; (3) from Contracaecum eudyptulae, which has a blunter tail and longer spicules; and (4) from Contracaecum variegatum, which possesses smaller-diameter, hooklike extensions on auricle lips, and a less robust interlabium with a more marked furrow. In this paper we present the first detailed description of C. pelagicum adults from S. magellanicus. Morphometric data between adult specimens of C. pelagicum from S. magellanicus and those from the black-browed albatross, Diomedea melanophris Temminck, from Argentinean coasts were compared. In addition, fourth-stage larvae that parasitized both hosts were assigned to a nondeterminated Contracaecum species. Ecological parameters for adults and larvae nematodes were calculated.

Helminths of the Magellanic penguin, Spheniscus magellanicus (Sphenisciformes), during the breeding season in Patagonian coast, Chubut, Argentina.

Abstract Twenty-seven Magellanic penguins, Spheniscus magellanicus (Sphenisciformes), were collected from September 1996 to November 2000 from Península Valdés (42°04′–42°53′S; 63°38′–64°30′W), on the Patagonian coast, Argentina and the gastrointestinal tract was examined for helminths. All birds were parasitized by at least 1 of the 5 following parasite species: Tetrabothrius lutzi (Cestoda); Cardiocephaloides physalis (Lutz, 1926) (Digenea), Contracaecum pelagicum (Johnston and Mawson, 1942), Cosmocephalus obvelatus (Creplin, 1825) (Nematoda), and Corynosoma sp. (Acanthocephala). The total mean intensity was 686. The helminth community composition of S. magellanicus is reported for first time in Argentina increasing the host range of many of the species registered.

TWO NEW SPECIES OF LITOMOSOIDES (NEMATODA: FILARIOIDEA) IN SIGMODONTINES (RODENTIA: MURIDAE) FROM RIO DE LA PLATA MARSHLAND, ARGENTINA

Two new species of coelomic filarioid belonging to Litomosoides are described from sigmodontine murids from the Rio de La Plata marshland, Argentina. Litomosoides bonaerensis n. sp., a parasite of Oligoryzomys delticola, belongs to the carinii group and is close to L. silvai, which differs by the head and tail papillae, buccal capsule and cavity, area rugosa, and morphology of the microfilaria. Litomosoides oxymycteri n. sp., from Oxymycterus rufus, belongs to the sigmodontis group. Differential diagnosis is based on the morphology of the buccal capsule, the head and tail papillae, and microfilaria. The ectoparasitic gamasid Ornithonyssus bacoti, in which several Litomosoides species develop, has been recovered from sigmodontines trapped in the study.

A NEW SPECIES OF TRICHURIS (NEMATODA: TRICHURIDAE) FROM PHYLLOTINI RODENTS IN ARGENTINA

A new species of Trichuris is described. Trichuris pardinasi n. sp. was recovered from Phyllotis xanthopygus Waterhouse (Rodentia: Muridae: Phyllotini) in Sierra de la Ventana, Buenos Aires Province, and Pampa de Achala, Córdoba Province (Argentina). This is the first record of Trichuris parasitizing Phyllotini rodents. The new species can be differentiated from the other 10 species parasitizing rodents from South America by the absence of the spicular tube, spicular sheath with spines uniformly distributed, the length of spicule, the J-shaped proximal cloacal tube, and the nonprotrusive vulva. Also, a description of the bacillary band is provided. The present and the future findings of shared parasite fauna from both populations of P. xanthopygus in these disjunct areas will support the hypothesis of a continuous distribution of this host species at a past time.

A new species of Syphacia (Nematoda: Oxyuridae) from Akodon azarae (Rodentia: Cricetidae) in Argentina.

Eight species of Syphacia (Nematoda: Oxyuridae) have been reported from South America in rodents of the Sigmodontinae, only 1 of which has been recorded in Argentina. Syphacia (Syphacia) carlitosi n. sp. is described from the ceca of Akodon azarae bibianae and Akodon azarae hunteri (Sigmodontinae: Akodontini) captured in 3 provinces in the northeast region of Argentina. The new species is differentiated principally by the shape of the cephalic plate; distribution of submedian papillae and amphids; presence, extent, and shape of cervical alae in females; absence of lateral alae; absence of deirids; spicular and gubernaculum length; shape and structure of accessory hook of gubernaculum; and distance of mamelons, excretory pore, and vulva from the anterior extremity. This is the second record of Syphacia parasitizing rodents of the tribe Akodontini.

A NEW SPECIES OF MATHEVOTAENIA (CESTODA: ANOPLOCEPHALIDAE) AND OTHER TAPEWORMS FROM MARSUPIALS IN ARGENTINA

Cestodes are reported from Didelphis albiventris Lund, 1840 and Micoureus cinereus Temminck, 1824 (Marsupialia: Didelphidae) in Argentina. These include a new species of Mathevotaenia Akhumyan, 1946 (Cestoda: Anoplocephalata) as well as M. bivittata (Janicki, 1904) and an unknown hymenolepidid cestode. Mathevotaenia argentinensis n. sp. is characterized by a relatively narrow strobila, 18–37 mm in total length and 1.0–1.5 mm in maximum width, 135–163 craspedote proglottids, 19–27 testes, and a muscular genital atrium. This species differs from M. didelphidis (Rudolphi, 1819) in the disposition of the genital ducts between the excretory canals and in the entrance of the vagina into the genital atrium posterior to the cirrus pouch; from M. paraguayae Schmidt and Martin, 1978 in the disposition of the genital ducts, absence of a seminal receptacle, and presence of an armed cirrus; and from M. boliviana Sawada and Harada, 1986 and M. pennsylvanica Chandler and Melvin, 1951 in the presence of an armed cirrus. Linstowiines appear to be the dominant cestodes in New World marsupials, with M. bivittata representing the most prevalent and widely distributed species. The hymenolepidid is the first record of this family in Neotropical marsupials.

Parasites of the Silversides Odontesthes smitti and Odontesthes nigricans (Pisces: Atherinopsidae) from Argentinean Patagonia

Abstract Seventeen parasite species (1 microsporidean, 1 cestode, 5 digeneans, 6 nematodes, 2 acanthocephalans, and 2 copepods) were recovered from a total of 356 Odontesthes smitti and 125 Odontesthes nigricans (Atherinopsidae). Fishes were collected from Nuevo and San José gulfs, Argentinean Sea, from April 2003 to February 2005. The following parasites were found: Microsporidia (xenomas); Cestoda: Tetraphyllidea plerocercoid larvae; Digenea: Prosorhynchoides sp. metacercariae (Bucephalidae), Aponurus laguncula, Lecithaster sp. (Lecithasteridae), Proctotrema sp. (Monorchiidae), Diphterostomum sp. (Zoogonidae); Nematoda: Cucullanus marplatensis (Cucullanidae), Huffmanela moraveci (Trichosomoididae), Cosmocephalus obvelatus L3 (Acuariidae), Anisakis sp. L3, Pseudoterranova sp. L3, Contracaecum sp. L3 (Anisakidae); Acanthocephala: Corynosoma sp. cystacanth larvae (Polymorphidae), Hypoechinorhynchus sp. (Arhythmacanthidae); Crustacea: Bomolochus globiceps (Bomolochidae) and Peniculus sp. (Penelidae). Odontesthes smitti and O. nigricans are new host records for most these parasites.

A New Anisakid Species Parasitizing the Imperial Cormorant Phalacrocorax atriceps From the North Patagonian Coast, Argentina

The anisakid species Contracaecum chubutensis n. sp. was found parasitizing the imperial cormorant Phalacrocorax atriceps at 2 different localities, Bahía Bustamante (45°11′S, 66°30′W) and Puerto Madryn (42°47′S, 65°02′W) on the Patagonian coast. Morphometrical analysis and further studies of adult specimens of C. chubutensis n. sp. and fourth-stage larvae of Contracaecum sp. were done using light and scanning electron microscopy. The possession and disposition of 7 pairs of tail papillae differentiate this new species from C. osculatum, C. radiatum, C. plagiaticium, and C. mirounga. Double-sized spicules separate it from C. variegatum and C. pelagicum. Moreover, the paracloacal papillae disposition and tail shape differentiate this new species from C. travassosi. The presence of bifurcated interlabia separate it from C. ogmorhini and C. margolisi. Three well-marked lip notches, a sharp tail shape, and the of the transversal paracloacal papillae disposition distinguishes C. chubutensis n. sp. from C. magnipapillatum and C. septentrionale. The species here described can be differentiated from C. caballeroi by its bifurcated interlabia, longer spicules, and for possessing more precloacal papillae pairs. It can be separated from C. rudolphii by a thinner interlabia at the base, deeper lip notches, a sharper tail, the disposition of transversal paracloacal papillae, and greater distance between both papillae of the first subventral distal papillae pair. In addition, fourth-stage larvae recovered from the same host and localities were identified and described as Contracaecum sp. Prevalence of adult parasites was 66.7 %, mean intensity was 4.0, and mean abundance was 7.1.

PARASITES OF THE STOUT RAZOR CLAM TAGELUS PLEBEIUS (PSAMMOBIIDAE) FROM THE SOUTHWESTERN ATLANTIC OCEAN

Abstract This work describes the parasites and their respective pathologies in the stout razor clam, Tagelus plebeius (Lightfoot, 1786) (Psammobiidae) from Argentinean coasts. It represents the first report about a histopathological survey for these species in the Southwestern Atlantic. Specimens of T. plebeius were collected at Mar Chiquita coastal lagoon (37°46′S, 57°27′W) (n = 104 dissected under stereomicroscope, n = 28 histologically sectioned and microscopically examined) and from the mouth of the Quequén Salado River (38°56′S, 60°33′W) (n = 14 dissected under stereomicroscope). Tagelus plebeius was found housing two ciliate species without apparent host reaction and acting as first intermediate host for two digenetic trematode species of the families Fellodistomidae and Gymnophallidae, by hosting sporocysts (mainly in gonad and digestive gland that results in the replacement of host tissues) and as second intermediate host by housing a gymnophallid metacercaria. Likewise, T. plebeius was found parasitized by a larval spirurinae nematode encapsulated by hemocytes. The finding of two ciliate species, the gymnophallid cercaria and metacercaria, and the larval nematode represents the first record for the host. The Southwestern Atlantic populations of this clam seem to be devoid of serious pathogens in the study area.