Coccidia (Apicomplexa: Eimeriidae) from the Subterranean Rodent <i>Ctenomys opimus</i> Wagner (Ctenomyidae) from Bolivia, South America

Of 35 tuco-tucos (Ctenomys opimus) collected in Bolivia, South America, 31 (88%) had eimerian oocysts in their feces at the time they were examined. Eighteen (58%) of the 31 infected animals were concurrently infected with 2 or 3 eimerian species. Four species of Eimeria were recovered and are described as new species based on the characteristics of sporulated oocysts. Oocysts of Eimeria granifera n. sp. were ellipsoidal, 21.1 x 17.2 (15-26 x 11-20) ,um with sporocysts ovoidal, 11.3 x 7.1 (8-14 x 5-9) ,um. Oocysts of Eimeria montuosi n. sp. were spheroidal, 24.2 x 22.0 (21-28 x 18-25) Am with sporocysts ovoidal, 10.5 x 7.3 (8-14 x 6-9) Am. Oocysts of Eimeria opimi n. sp. were spheroidal to subspheroidal, 24.3 x 21.8 (18-29 x 15-26) Am with sporocysts ovoidal, 11.6 x 7.6 (10-13 x 6-9) Am. Oocysts of Eimeria oruroensis n. sp. were spheroidal to subspheroidal, 27.3 x 23.6 (23-32 x 20-28) ,m with sporocysts ovoidal, 13.2 x 8.6 (10-16 x 8-11) ,um. The Ctenomyidae is 1 of 11 families belonging to the suborder Hystricognathi (see Mares and Ojeda, 1982). The geologic age of the family is Pliocene to Recent in South America (Nowack and Paradiso, 1983). Relatively little is known of the endoparasite fauna of these subterranean rodents, and, until the present paper, no coccidia had been reported from this group of mammals. Since 1984, fecal samples, helminths, ectoparasites, and other data (skin, skeleton, chromosomes, tissues for electrophoresis) have been collected from several populations of Ctenomys opimus Wagner from various localities in western Bolivia, South America (Fig. 1). In these hosts we found sporulated oocysts representing 4 new species of Eimeria, which we describe here. MATERIALS AND METHODS All hosts were necropsied in the field promptly after capture. Organs were examined for the presence of metazoan parasites and fecal pellets were removed from the lower bowel of each animal and preserved in vials containing 2.0% aqueous (w/v) K2Cr207. Upon return from Bolivia, samples were filtered and the fecal debris was then incubated at room temperature (24 C) for 20 days. Samples were then examined by coverslip flotation as described by Duszynski et al. (1982). Oocysts were measured with an ocular micrometer and photographed with Panatomic-X 35-mm film within a Zeiss Universal Photomicroscope equipped with both Neofluar and Nomarski-interference 100 x objective lenses. All measurements are in ,m with the ranges in parentheses. Received 30 May 1988; revised 10 July 1988; accepted 21 July 1988. RESULTS The coccidians with which hosts were infected and collection localities are presented in Table I. Eimeria granifera n. sp. (Figs. 2, 3, 11) Description: Oocyst subspheroidal/ellipsoidal, wall of uneven thickness (Fig. 2) ~2.0, composed of 2 layers: outer wall smooth, -3/4 of total thickness, pale blue to transparent; inner layer yellow; polar body present in about 44% of the oocysts; oocyst residuum absent; sporulated oocysts (n = 75) 21.1 x 17.2 (15-26 x 1120) with L:W ratio 1.2 (1.1 x 1.9); sporocysts (n = 75) ovoidal, 11.3 x 7.1 (8-14 x 5-9) with L:W ratio 1.6 (1.2 x 2.0); button-like Stieda body present (Figs. 2, 3), but suband parastieda bodies absent; sporocyst residuum of 10-12 large globules in a compact mass of varying shape, wedged between sporozoites (Figs. 2, 3); each sporozoite large, folded, highly granular with a large posterior refractile body (Figs. 3, 11). Oocysts were 274-275 days old when measured.