Morphological and molecular evidence of Oslerus osleri (Nematoda: Filaroididae) in the Andean fox (Lycalopex culpaeus).

Oslerus osleri is a cosmopolitan filaroid nematode that parasitizes the respiratory system of domestic and wild canids. Natural infection by O. osleri is reported in the Andean fox (Lycalopex culpaeus) in this study. Nematodes, enclosed in small and compact fibrous nodules of 1 to 5 mm in diameter, were found on the surface of the trachea near the bronchial bifurcation on four Andean foxes during necropsy (one from Cuzco, Peru and three from Northwestern Patagonia in Argentina). The nematodes were identified as O. osleri by morphological and molecular methods. Ribosomal and mitochondrial DNA analyses were performed amplifying the second internal transcribed spacer region (ITS-2), the partial cytochrome c oxidase 1 (cox1), and the large subunit of nuclear ribosomal RNA (LSU rRNA) genes. Sequences of the ITS-2 and LSU rRNA had a genetic variation of 1.5% and 1.0%, respectively, with previous sequences of O. osleri registered in Genbank. This is the first amplification of the cox1 gene of O. osleri and demonstrated an identity of 92% to Perostrongylus falciformis (KY365437), and 90% to Angiostrongylus cantonensis (KY779735) and Angiostrongylus costaricensis (AP017675).

Pathology associated with larval eustrongylides sp. (nematoda: Dioctophymatoidea) infection in galaxias maculatus (actinopterygii: Galaxiidae) from patagonia, Argentina.

Helminth infections within tissues tend to be subjected to a host response that can include encapsulation and melanization to isolate the parasite. The effectiveness of this response depends on the host species. During a survey of parasites of the native fish, Galaxias maculatus, we found conspicuous, strongly melanized exterior cysts located in the caudal peduncle of the fish. Dissection of these cysts exposed larval nematodes whose morphometrical features allowed their identification as Eustrongylides sp. Species of this genus are distributed worldwide. Galaxias maculatus was previously reported as second intermediate host to Eustrongylides sp. larvae, and the aquatic bird Podiceps major was cited as definitive host of Eustrongylides tubifex in Andean Patagonian lakes. The site of infection in the fish, and the host's response are unique among infections by larvae of Eustrongylides sp. in fishes, so the objective of this study was to describe the histological injury caused by larvae of the genus Eustrongylides parasitizing G. maculatus. Samples of fish were taken near the shore of Gutiérrez lake, in northwestern Patagonia. Some larval morphometric features were described to confirm the identity of larvae to generic level. Histopathological analysis (tissues sectioned at 5-7 µm, stained with Hematoxylin and Eosin, and Masson's Trichrome) of the caudal peduncle revealed almost complete disappearance of the epaxial musculature due to compressive atrophy and a chronic inflammatory response, associated mainly with a dense fibrotic capsule and an intense melanic deposit. This is the first description of the histopathology of an external cyst caused by Eustrongylides sp. larvae in fishes.

Hamatospiculum flagellispiculosum (Nematoda: Diplotriaenidae) causing severe disease in a new host from Argentine Patagonia: Campephilus magellanicus (Aves: Picidae).

We describe pathological aspects of an infection caused by parasitic nematodes in skeletal muscles of a Magellanic woodpecker (Campephilus magellanicus), providing the first description of any disease findings in this species. A weakened female with locomotory dysfunction was rescued near Bariloche city (Argentine Patagonia), which soon died. At the necropsy, unexpected masses of tissue were located at three joints (legs and tail). A dissection of these masses exposed numerous nematodes in the musculature surrounding the joints that were identified as Hamatospiculum flagellispiculosum (Nematoda: Diplotriaenidae), a species that was not previously found in Piciformes (woodpeckers, toucans, and allies) of the Neotropical Region. In this report, we complement the original parasite description from 1952 with SEM images, and extend the species range about 2000 km southwards. Histopathological analysis (tissues sectioned 4-6 microns, stained with hematoxylin and eosin) of the affected tissues revealed parasitic myositis with muscle fibrosis. Severe muscle degeneration and necrosis, fibrous tissue replacing muscle tissue, chronic inflammation with widespread diffuse mononuclear infiltration, and parasitic content (adult roundworms, eggs, and eggs with first-stage larvae) were present in all samples. The multifocal nature of these lesions was consistent with the locomotory dysfunction exhibited by the bird. Both the immune response (mononuclear infiltration without eosinophils, which normally fight helminth colonization) and the clinical severity of this case (a lethal, multifocal macroparasite infection) are noteworthy. The expected immune response may have been suppressed through immunomodulation by the parasite, as observed for filarial parasites. Based on their demography and life history traits (i.e., long-lived picids that produce a single nestling every 1-2 years, and live in sparse populations), Magellanic Woodpeckers do not seem to be obvious hosts of an obligately killing parasite, and other (more regular) hosts should be expected to occur in the same region.

The Behavior Response of Amphipods Infected by Hedruris suttonae (Nematoda) and Pseudocorynosoma sp. (Acanthocephala).

The manipulation of intermediate host behavior may increase chances of parasite transmission to the definitive host. In freshwater environments of the Neotropical Region, studies on behavioral manipulations by parasites are rare, and the majority of these consider only a single parasite species and/or 1 life stage of a particular parasite species. In Andean Patagonian lakes of Argentina, the amphipod Hyalella patagonica is infected by larvae of the fish nematode Hedruris suttonae and by the bird acanthocephalan Pseudocorynosoma sp. The 3 objectives of the present study were to determine whether H. suttonae and Pseudocorynosoma sp. differ in their effects on behavior of H. patagonica , whether such modification is associated with parasite development, and to assess the associations between behavioral traits. From naturally parasitized amphipods, activity (swimming levels) and phototaxis (light preference) was measured. Only in phototaxis trials did larvae of H. suttonae induce significantly higher levels of photophilia, suggesting that they are manipulative. Scores of activity and phototaxis were positive and significantly related for non-parasitized female amphipods and for amphipods parasitized by larvae of Pseudocorynosoma sp. but were not associated in amphipods parasitized with larvae of H. suttonae (infective and non-infective), suggesting that infection separated the relationship between these variables.

A new microphallid (Digenea) species from Lontra provocax (Mammalia: Mustelidae) from freshwater environments of northwestern Patagonia (Argentina).

A new microphallid species of Maritrema is described from the native southern river otter, Lontra provocax (Thomas). A naturally infected otter was found dead in the Nahuel Huapi National Park, Argentina. Ovigerous adult worms were recovered from the anterior portion of the intestine. Specimens of Maritrema huillini n. sp. have an unarmed genital pore and glabrous cirrus. They can be distinguished from all other species in the genus by having a long intestinal ceca extending up to three-quarters of the testes length to the level of the posterior border of the testes and a metraterm composed of a proximal sphincter, a non-muscular sac, and a distal muscular portion. This microphallid is the first species recovered from a South American eutherian host and the first digenean recorded for L. provocax.

Two new species of Cryptocephalum n. gen. (Monogenoidea: Dactylogyridae) from the cephalic lateral line of Percichthys trucha (Perciformes: Percichthyidae) in Patagonia, Argentina.

Two new species of Monogenoidea were found parasitizing the cephalic lateral line canals of Percichthys trucha (Valenciennes) (Perciformes: Percichthyidae). These species are described as members of a newly proposed genus of Dactylogyridae. Cryptocephalum n. gen. is characterized by the site of infection and the combination of the several features: ventral and dorsal anchor/bar complexes, anchors with strongly elongated shaft and recurved point, shaft and point of dorsal anchors protruding laterally from haptor, hooks with 2 subunits and with pair 5 smaller than the others; gonads overlapping; coiled male copulatory organ with counterclockwise rings, accessory piece formed by 2 distinct parts, and a tubular, sclerotized ventral vagina. C ryptocephalum petreum n. sp. is characterized by having both anchor pairs protruding laterally from haptor, male copulatory organ with a coil of 2-1/2 rings, accessory piece tweezers-shaped, and sclerotized vaginal vestibule. Cryptocephalum spiralis n. sp. has ventral anchors protruding ventrally and dorsal ones protruding laterally, male copulatory organ with a coil of 1-1/2 rings, the antero-dorsal part of the accessory piece saddle-shaped, vaginal vestibule not present, and coiled vagina. This is the first record of Dactylogyridae species parasitizing the cephalic lateral line of fishes.

The relationship between fish assemblages and the helminth communities of a prey fish, in a group of small shallow lakes.

Galaxias maculatus (small puyen) is an abundant native fish distributed in lakes and rivers of the Patagonia, and it is the frequent prey of other fishes, fish-eating birds, and mammals. Previous studies have shown that it is parasitized by 33 metazoan species and that the richness and composition of the parasite communities vary between lakes. The aim of the present work was to analyze the relationship between the composition of fish assemblages and the helminth component community structure of G. maculatus . Ten environmentally similar, small, shallow lakes, belonging to the Nahuel Huapi Lake basin, were chosen because of the differences in the native fish assemblages. Parasite community structure in G. maculatus varied according to the fish assemblage of each lake. The presence of the piscivorous fish Percichthys trucha regularly produced variations in the composition and richness at the component and infracommunity levels, as well as the percentage of autogenic parasite species in G. maculatus .

A new hedrurid species (Nematoda) from galaxiid fishes in Patagonia (Argentina) and infection of amphipods as intermediate host.

During a parasite survey of galaxiid fishes (Galaxiidae) from Patagonian Andean lakes, a new species of nematode, Hedruris suttonae n. sp. was collected from the stomach of the native Galaxias maculatus (Jenyns) and G. platei (Steindachner). Specimens were examined by light and scanning electron microscopy, especially head morphology, female caudal prehensile structure, and distribution of spines. The new species is distinguished by body and tail size, morphology and size of spicules, the arrangement of caudal papillae in the male, the female caudal hook, and size of eggs. Hyalella patagonica (Ortmann), a Neotropical species of Amphipoda, is reported as its natural intermediate host. Data regarding prevalence and mean intensity in the intermediate and definitive hosts are included. The diet and habitat of the hosts, the percentage of gravid females, the high values of prevalence, and mean intensity in galaxiid fishes, as well as the wide distribution of H. suttonae , collectively indicate that, in these oligotrophic Andean lakes, G. maculatus and G. platei are true definitive hosts of this nematode.

A new genus of Cystidicolid nematode from the stomach of Galaxias maculatus (Osmeriformes: Galaxiidae) in Patagonia (Argentina).

During a parasitological survey of Galaxias maculatus (Jenyns) from Patagonian Andean Lakes, specimens of a new species of nematode were collected from the stomach of fish and studied by light and scanning electron microscopy. This species is described as the only member of a newly proposed genus of Cystidicolidae by having oral opening dorsoventrally elongated, 2 lateral pseudolabia, 4 cephalic papillae, stoma (vestibule) elongated, esophagus divided into anterior muscular and posterior glandular sections, and caudal alae in males. Placonema n. gen. (Habronematoidea, Cystidicolidae) is characterized by the combination of the following features: oral opening dorsoventrally elongated demarcated by 4 sclerotized plates and 2 well-developed pseudolabia projected to the buccal cavity, each pseudolabium with conspicuous, conical, anterior protuberances. Four cephalic papillae and deirids simple. Male with caudal alae, area rugosa absent, 4 pairs of preanal papillae, unpaired papilla present on anterior cloacal lip, and 6 pairs of postanal papillae. Larvigerous eggs without filaments. Placonema pataguense n. gen. n. sp. infects the stomach of G. maculatus from Lake Patagua (Patagonia, Argentina) and is the first species of Cystidicolidae described from G. maculatus.

New cystidicolid species (Nematoda) from Galaxias platei (Osmeriformes: Galaxiidae) in Patagonian freshwater environments.

During a parasitological survey of Galaxias platei Steindachner, 1898, from Patagonian Andean Lakes, a new species of Cystidicolidae was found in the stomach of fish. The new species was described using light and scanning electron microscopy; the species has characteristics of Ascarophis and is distinguishable from other species by a combination of the following features: well-developed pseudolabia with T-shaped inner extensions, bifurcate deirids, small ratio GE:ME, small left spicule, small ratio LS:RS, and larvigerous eggs with thick and fine filaments in both poles. Intraspecific variation in the morphology of larvigerous eggs was studied. This is the first species of Ascarophis described from freshwater fishes.

A new genus of dactylogyrid from the gills of Galaxias maculatus (Osmeriformes: Galaxiidae) in Maullín Basin, Patagonia, Chile.

During a parasitological survey of Galaxias maculatus (Jenyns, 1842) in the Maullín Basin (Chilean Patagonia), specimens of a new species of Monogenea were collected from the gills. This species is described as the only member of a proposed new genus, Inserotrema n. gen. (Dactylogyridae, Ancyrocephalinae), characterized by similar hooks with 2 subunits, overlapping gonads, coiled cirrus with counterclockwise rings, articulated accessory piece formed by 2 parts, a needlelike sclerite threading the distal part of the MCO, and a sclerotized midventral vagina. This new genus is proposed for dactylogyrids from gills of galaxiids (Galaxiidae). Inserotrema puyei n. sp. infects gills of G. maculatus from Llanquihue Lake, Maullín River, and Maullín Estuary. This is the first species of Ancyrocephalinae described from gills of a galaxiid.

Allassogonoporus dromiciops n. sp. (Digenea: Allassogonoporidae) from Dromiciops gliroides (Marsupialia: Microbiotheriidae) in Patagonia, Argentina.

A new species of Allassogonoporus Olivier, 1938, from a naturally infected specimen of Dromiciops gliroides, is described. Adults of A. dromiciops n. sp. were recovered from the small intestine. This new species can be distinguished from all other species of the genus by having: the largest body and eggs, a lobed testes and ovary, a Y-shaped excretory vesicle and vitelline follicles beginning at the level of the posterior margin of the oral sucker. This is the first record of a species of Allassogonoporus in South America and the first record of a digenean parasitising D. gliroides.

Pseudodelphis limnicola sp. n. (Dracunculoidea: Guyanemidae) from the heart of Percichthys trucha (Perciformes: Percichthyidae) in Patagonian Andean Lakes (Argentina).

During a survey of parasites of Percichthys trucha (Cuvier et Valenciennes) (Perciformes: Percichthyidae) in northwestern Patagonian lakes, a new dracunculoid of the family Guyanemidae was found parasitizing as adults the heart of the fish. This species belongs to the genus Pseudodelphis Adamson et Roth, 1990 by having deirids, glandular multinucleate oesophagus and anterior branch of the uterus, and by lacking caudal alae and a gubernaculum. Pseudodelphis limnicola sp. n. differs from Pseudodelphis oligocotti Adamson et Roth, 1990 by the number and distribution of the cephalic papillae, a muscular oesophagus submerged into the glandular portion and by lacking a peribuccal ring. This is the first record of a guyanemid inhabiting the heart of a Neotropical perciform fish.

Catatropis hatcheri n. sp. (Digenea: Notocotylidae) from Heleobia hatcheri (Prosobranchia: Hydrobiidae) and notes on its life-cycle in Patagonia, Argentina.

A new species of Catatropis Oghner, 1905 from a freshwater Neotropical prosobranch snail, Heleobia hatcheri (Hydrobiidae), is described. Naturally infected snails were collected from Nahuel Huapí Lake in Andean Patagonia. The characteristics of the larval stages are also presented. Experimental adults were recovered from the distal region of the intestinal caeca of chicks and ducklings and natural adults from a wild duck Anas platyrhynchos. Adults of Catatropis hatcheri n. sp. can be distinguished from all other species of the genus in having 10-12 (11) ventral glands in each lateral row, the cirrus-sac extending back to between the first third and the middle of the body, the metraterm shorter than the cirrus-sac, a previtelline field of 1,258-1,544 (1,396), vitelline follicles reach back to the anterior border of the testes with some follicles extending slightly lateral to them, only external testicular margin lobed and genital pore in median line just posterior to the intestinal bifurcation. In addition, the eggs have one filament on each pole, the rediae contain one or two mature cercariae, and the cercariae are tri-oculate, with a long tail and encyst in the environment.

Notocotylus biomphalariae n. sp. (Digenea: Notocotylidae)from Biomphalaria peregrina (Gastropoda: Pulmonata) in Patagonia, Argentina.

A new species of Notocotylus was found parasiting a freshwater pulmonate snail, Biomphalaria peregrina. Naturally infected snails were collected from two temporary ponds in the Nahuel Huapí National Park in Patagonia. The characteristics of the larval stages are presented. Experimental adults were recovered from the intestinal caeca of ducks and chicks. Adults of Notocotylus biomphalariae n. sp. exhibit an aspinose tegument, two lateral rows of 11 ventral glands and a median row of four, a uterus with 12-16 coils of which 2-4 are previtelline, a metraterm equivalent in size to 65-68% of the cirrus-sac length, a previtelline field which extends to the middle of the body, a lobed testis and a genital pore closely posterior to the intestinal bifurcation. The rediae have one to three cercariae. The cercariae, when shed, are trioculate and have a long tail; they encyst in the environment and become infective 12 days after encystment.

Duplaccessorius andinus n. gen., n. sp. (Dactylogyridae: Ancyrocephalinae) from the gills of Percichthys trucha (Perciformes: Percichthyidae) in Patagonia, Argentina.

During a parasitological survey of Patagonian freshwater fishes, specimens of a new species of Monogenea were collected from the gills of Percichthys trucha (Perciformes: Percichthyidae). This species is described as the only member of a newly proposed genus of Ancyrocephalinae. Duplaccessorius n. gen. (Dactylogyridae, Ancyrocephalinae) is characterized by hooks with 2 subunits, gonads in tandem, a coiled male copulatory organ with counterclockwise rings, an accessory piece formed by 2 distinct parts, and a nonsclerotized sinistrolateral vagina with a funnel shape vestibule. Duplaccessorius andinus n. sp. infects the gills of P. trucha (Cuvier and Valenciennes, 1840) from Andean Patagonian lakes, being the first species of Ancyrocephalinae described from a South American percichthyid.

Allocreadium pichi n. sp. (Trematoda: Allocreadiidae) in Galaxias maculatus (Osteichthyes: Galaxiidae) from Lake Moreno in Patagonia (Argentina).

Allocreadium pichi n. sp. (Trematoda: Allocreadiidae) is described from the intestine of Galaxias maculatus (Osteichthyes: Galaxiidae) from Moreno Lake in Patagonia, Argentina. This species is distinguished from A. patagonicum Shimazu, Urawa & Coria, 2000, the other species recorded in the area, by its smaller body size, the diagonal position of the testes and different ratios of the suckers, testes and cirrus-sac in relation to body size. In addition, the synonymy of A. patagonicum with Polylekithum percai Ostrowski de Núñez, Brugni & Viozzi, 2000 is proposed herein.

Posterotestes unelen gen. et sp. n. (Digenea: Apocreadiidae) from Percichthys trucha (Osteichthyes: Percichthyidae) in Patagonia, Argentina.

Posterotestes gen. n. (Digenea: Apocreadiidae, Apocrcadiinae) is proposed for specimens with the following features: spiny body, posterior position of gonads, extension of vitelline follicles up to level of intestinal bifurcation and absent at post-testicular space, long oesophagus and extension of caeca up to anterior testis. Posterotestes unelen sp. n. is described from the intestine of the native fish, Percichthys trucha (Cuvier et Valenciennes) (Osteichthyes: Percichthyidae) from Patagonian Andean lakes.