ISOSPORA-ATRATA N-SP (APICOMPLEXA, EIMERIIDAE) - A NEW COCCIDIUM ISOLATED FROM CARDUELIS-ATRATA (PASSERIFORMES, FRINGILLIDAE)

Large numbers of coccidian oocysts belonging to the genus Isospora wer e obtained from the intestinal contents of 98 Carduelis atrata importe d into Italy from South America during the months of August through De cember 1994. The oocysts are subspherical and average 21 X 20.3 mu m ( 19.4-23.5 mu m X 18.5-22 mu m), have a bilayered wail, and an oval pol ar granule (rarely two). The sporocysts are elliptical and measure 18. 8 mu m X 10.3 mu m (17.5-18.94 mu m X 9.5-11.0 mu m). The Stieda body protrudes slightly from the end of the sporocyst. A large sporocyst re siduum is present, consisting of many granules that may be in a compac t mass or scattered. Since this Isospora sp.does not resemble any othe r species of Isospora previously described from birds of the genus Car duelis, it has been named Isospora atrata n. sp. after the host. Disse minated asexual stages were found in mononuclear cells derived from fo rmalin-fixed post mortem material, suggesting this coccidian may repre sent an Atoxoplasma-like parasite. Four coccidia-free Serinus canarius L. cohabitated for a lone period (4 mo) with infected C. atrata but o ocysts were never found in the stool of these birds.