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Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 94(6): 725-726, Nov./Dec. 1999 RESEARCH NOTE Helminths Parasites of Eupsophus roseus (Anura: Leptodactylidae) from Southern Chile Sonia Puga+, Patricio Torres Instituto de Parasitología, Universidad Austral de Chile, Casilla 567, Valdivia, Chile + Corresponding author. Fax: +56-63-214475. E-mail: parasito@uach.clReceived 21 January 1999 Code Number:OC99219 Key words: helminths - Nematoda - Trematoda -Acanthocephala - Anura - Eupsophus roseus Eupsophus roseus Dumeril & Bibrón, 1841 is a small sized (2.6-9.5 cm) endemic frog of the temperate Nothofagus forests of Southern Chile (JR Formas 1979 Univ Kansas Mus Nat Hist Mongr 7: 341-369). In this species the following parasite endohelminths have been reported: Oswaldocruzia neghmei Puga, 1981, Rudolphitrema chilensis Puga, 1986 (S Puga 1994 Bol Chil Parasitol 49: 81-84) and Centrorhynchus sp. (P Torres & S Puga 1996 Mem Inst Oswaldo Cruz 91: 717-719). The aims of this survey were to determine the prevalence and mean intensity of infection by parasitic helminths in a population of E. roseus from Southern Chile. Forty four live specimens of E. roseus were collected by hand from Isla Teja (39º48S; 73º15W) in the Province of Valdivia during different seasons between 1994 to 1997. They were kept moist and cool in cages and taken to the laboratory within 6 hr of capture and killed by pithing within the next 24 hr. Snout-vent length was determined prior to necropsy. The abdomen was opened by a longitudinal incision from vent to throat and the gastrointestinal tract was removed, slit longitudinally, and examined for helminth parasites under a dissecting microscope. Mesenteries, liver, spleen, gonads, and urinary bladder were also examined. Sex was determined after necropsy. Helminths were washed in saline solution. Nematodes were fixed in ethanol 70ºGL or 10% formalin. Acanthocephalans and trematodes were held in distilled water at 4ºC for 24 hr, and fixed in alcohol-formalin-acetic acid and 10% formalin, respectively. Nematodes and acanthocephalans were cleared in lactophenol and trematodes were stained with Gower's carmine for identification. The terminology used has been taken from A Bush et al. (1997 J Parasitol 83: 575-583). The Fisher and Mann-Whitney U tests were used to study the differences in prevalence and mean intensity of infection respectively (S Siegel 1991 Estadística no Paramétrica, Trillas, México, 344 pp.). Four helminths taxa were found ( Table I), two of them (A. artigasi and Cosmocerca sp.) for the first time in E. roseus. All parasite specimens were adults, with the exception of Centrorhynchus sp. (cystacanths). A. artigasi, R. chilensis and Centrorhynchus sp. are parasites of E. roseus and Eupsophus calcaratus (Günther, 1881) and have not been observed in other anuran species (S Puga 1994 Bol Chil Parasitol 49: 81-84, Torres & Puga loc. cit., Puga & Torres loc. cit.). The highest prevalences of infection were registered for the nematode species whose genera include direct life cycles species (RC Andersen 1991 Nematode Parasites of Vertebrates, CAB International, United Kingdom, 578 pp.), in contrast to Centrorhynchus sp. and R. chilensis which present indirect life cycles. A. artigasi showed the greatest mean intensity infection (Table I).The sex was determined in 33 anurans, of which only four were males. In view of this the analysis of prevalence and mean intensity of infection with respect to the size of the hosts and the seasons in which they were collected, were made only with females. A. artigasi was only found in the smaller female frogs (2.6-6 cm), but Cosmocerca sp. was observed in females of different length (2.6-9.5 cm) ( Table II). The prevalence of infection by Cosmocerca sp. was highest (P=0.036) in the larger female frogs, but the mean intensity was similar in frogs of all length (U=0.50; P>0.05). A. artigasi was isolated in three of four seasons in the small female frogs (infected/examined), from the Summer (2/10), Autumn (1/3), and Winter (3/7). Cosmocerca sp. was recovered three of four season during Summer (4/10), Winter (1/7), and Spring (1/2) in the small sized animals and among the larger ones in Winter (3/3). Centrorhynchus sp. and R. chilensis were registered in Winter (2/10) and Autumn (1/5), respectively.Voucher specimens of different taxa have been deposited in the collection of the Institute of Parasitology, Universidad Austral de Chile, Valdivia, Chile (IPUAT No. 0259-0261). This work was supported by grant No. S-94-34 (Dirección de Investigación y Desarrollo, Universidad Austral de Chile). Copyright 1999 Fundacao Oswaldo Cruz - Fiocruz The following images related to this document are available:Photo images[oc99219a.jpg] [oc99219b.jpg] |
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