María A. Rossin

Causes of inter-individual variation in reproductive strategies of the parasitic nematode Graphidioides subterraneus

Several factors capable of affecting the amount of resources available to an individual parasite, such as the number of other parasites in the host or host quality, may cause variability in reproductive success among parasites. Variation in egg output and mean egg volume was investigated among adult females of the nematode Graphidioides subterraneus, parasitic in the herbivorous subterranean rodent Ctenomys talarum (Octodontidae). Female nematode body size correlated strongly with the number of eggs produced. However, neither host body mass nor the number of other nematodes per host had any influence on the number or volume of eggs produced by the parasites. There was also no evidence for a trade-off between the number of eggs produced and mean egg volume among female nematodes. All these results suggest that resource supply to individual worms is not limited by host size or by the number of conspecific parasites vying for the same resources, despite the 30-fold variation in intensity of infection and the twofold variation in host body mass observed in the present study. Instead, resource availability does not appear to constrain reproduction in G. subterraneus, with its host providing a stable, predictable environment.

A new species of Capillaria (Nematoda: Capillariidae) parasitizing Conger orbignianus (Pisces: Congridae) from Argentina.

Capillaria (Procapillaria) navoneae n. sp. is described from the congrid fish Conger orbignianus from waters off Mar del Plata, Argentina (38°08′S, 57°32′W) (prevalence 29.17%, mean intensity ± SD 6.07 ± 6.59). The new species is assigned to the subgenus Procapillaria Moravec, 1987, despite the absence of vulvar appendages in gravid females. Of the 3 species so far known in the subgenus, the new one most closely resembles C. (P.) margolisi, from which it is distinguished by lacking a medial expansion in the spicule and a slightly elevated anterior lip of vulva, and by having a shorter esophagus, a larger number of stichocytes, and a shorter tail.

A NEW SPECIES OF PARACAPILLARIA (NEMATODA: CAPILLARIIDAE) PARASITIZING THE BRAZILIAN SANDPERCH, PINGUIPES BRASILIANUS (PISCES: PINGUIPEDIDAE), FROM ARGENTINA

A new species, Paracapillaria argentinensis n. sp., is described from the pinguipedid fish Pinguipes brasilianus Cuvier, 1829 from waters off Mar del Plata, Argentina (38°08′S, 57°32′W) (prevalence 22.2%; mean intensity ± SD, 4.42 ± 5.19). The new species is assigned to the subgenus Paracapillaria Moravec, 1987. Of the 10 species so far known in the subgenus, the new species more closely resembles P. (P.) plectroplites, from which it is distinguished by having a spicule with an expanded anterior end and a slender medial section. A similar spicular morphology is observed in P. (P.) epinepheli; however, it shows shorter spicules and a highly reduced caudal bursa. This is the first record of Paracapillaria in the southwestern Atlantic Ocean.

A new species of Trichostrongylus (Nematoda, Trichostronglyoidea) parasitizing the subterranean rodent Ctenomys talarum (Rodentia, Octodontidae) from Mar de Cobo, Argentina

A new nematode species, Trichostrongylus duretteae sp. nov., found in the small intestine of Ctenomys talarum from Argentina is described. The new species more closely resembles T. suis lwanitsky, 1930 a parasite of Sus scrofa in the USSR. However, the new species can be distinguished by the morphology of male genital bursa: Rays 6 distant from rays 8 and a larger dorsal ray in relation to the length of rays 2 to 8. The present finding is the first record of the genus Trichostronglyus in rodents of the family Octodontidae.

A NEW SPECIES OF NEOASCAROPHIS (NEMATODA: CYSTIDICOLIDAE) PARASITIC IN MACROURUS CARINATUS (MACROURIDAE) FROM ARGENTINEAN WATERS

Abstract: Nematodes of the cystidicolid Neoascarophis Machida, 1976, are all parasites of macrourid fishes, making up at present 5 species. Several other unidentified species have also been reported in several fish species from the northern and southern Atlantic Ocean, including 1 from Macrourus carinatus (Günther) (Macrouridae) in the southwest Atlantic Ocean. During a parasitological survey carried out on samples of M. carinatus from Patagonian waters, nematodes referable to Neascarophis were found in ulcers in the gastric mucosa. These nematodes Neascarophis sphaerocaudata n. sp. closely resemble N. macrouri by the posterior position of the vulva and the dilated posterior extremity in females. However, the new species differs from N. macrouri mainly by its larger size, a larger muscular esophagus, and a widely globose posterior extremity in females. SEM study of cephalic structures also showed morphological differences between both species, especially in the morphology of the submedian labia and lateral pseudolabia. In view of these differences a new species is proposed.

A New Species of Capillostrongyloides (Nematoda: Capillariidae) Parasitizing the Horsefish, Congiopodus peruvianus (Pisces: Congiopodidae), from Argentina

Abstract A new species of parasitic nematode, Capillostrongyloides congiopodi n. sp. (Capillariidae), is described based on specimens collected from the gall bladder of the horsefish, Congiopodus peruvianus Cuvier and Velenciennes (Congiopodidae, Scorpaeniformes), from the Patagonian Shelf, Argentina (45–48°S; 60–64°W). Among the 9 species described so far in the genus, the new species most closely resembles C. norvegica Moravec and Karlsbakk, 2000, by the presence of its conspicuously elevated anterior vulvar lip in females; however, it is readily distinguished from it by having a larger body size, larger eggs with protruding polar plugs, the shape and length of the spicule, and mainly by the general morphology of the caudal bursa of males. In addition, the site of infection, i.e., stomach versus gall bladder. This is the first Capillostrongyloides species reported from fishes in the southern Atlantic Ocean.

Figures 1 – 8. Characithecium Chascomusensis N In Characithecium (Monogenoidea: Dactylogyridae) Parasitic On The Neotropical Fish Oligosarcus Jenynsii (Teleostei: Characidae) From The Pampasic Region, Argentina, With The Emendation Of The Genus

FIGURES 18 – 26. Characithecium robustum n. sp. 18. whole mount, ventral view. 19. male genital complex, ventral view. 20. Egg. 21. vagina, ventral view. 22. ventral bar. 23. dorsal bar. 24. ventral anchor. 25. dorsal anchor. 26. hook. Scale bars: 18 = 125 Μm; 19 = 10 Μm; 20 – 26 = 20 Μm.