Identification and genetic characterization of a novel species of Choleoeimeria Schneider, 1875 from a captive-bred bilby (Thylacomyidae; Macrotis lagotis) (Reid, 1837) in Western Australia

A novel Eimeria sp. from a captive-bred bilby (Macrotis lagotis Reid, 1837) has been identified in Western Australia. The bilby was bred at the Kanyana Wildlife Rehabilitation Centre, Perth, as part of the National Bilby Recovery Plan. Oocysts (n = 31) irregular blunt ellipsoidal, 17-18 × 11-12 (17.2 × 11.3); length/width (L/W) ratio 1.4-1.5 (1.5). Wall bi-layered, 0.8-1.0 (0.9) thick, outer layer smooth, c.2/3 of total thickness. Micropyle barely discernible. Oocyst residuum is absent, but 2-3 small polar granules are present. Sporocysts (n = 31) ovoidal, 7-8 × 5-6 (7.8 × 5.7); L/W ratio 1.3-1.4 (1.4). Stieda, sub-Stieda and para-Stieda bodies absent or indiscernible; sporocyst residuum present, usually as an irregular body consisting of numerous granules that appear to be membrane-bound or sometimes diffuse among sporozoites. Sporozoites vermiform with a robust refractile body. Further molecular characterization was conducted on the sporulated oocysts. At the 18S locus, it sat in a large clade of the phylogenetic tree with two isolates of Eimeria angustus from quendas (Isoodon obesulus Shaw, 1797) and the Choleoeimeria spp. It shared the highest identity with E. angustus (KU248093) at 98.84%; at the COI gene locus, it was unique and most closely related to Choleoeimeria taggarti, which is hosted by another species of marsupial, the yellow-footed antechinus (Antechinus flavipes flavipes), with 90.58% genetic similarity. Based on morphological and molecular data, this isolate is a new species and named as Choleoeimeria yangi n. sp.

DESCRIPTION OF A NEW EIMERIA SPECIES (APICOMPLEXA: EIMERIIDAE) RESPONSIBLE FOR CLINICAL COCCIDIOSIS IN COMMERCIAL CHUKAR PARTRIDGE (ALECTORIS CHUKAR)

Recurrent coccidiosis affecting a commercial chukar partridge (Alectoris chukar) farm in Ontario, Canada was investigated. The responsible pathogenic Eimeria species was isolated for biological characterization. The uniformity of oocyst morphometrics supported that only a single Eimeria sp. was present. Experimental infections with coccidia-free chukars were used to describe exogenous and endogenous developmental stages of the parasite. The prepatent period of the causative Eimeria species was 5 days and patency lasted 11 days; fecundity was 1,573 to 30,057, with the highest fecundity recorded with the lowest challenge dose. Endogenous development was elucidated histologically from samples collected at 8 locations along the intestinal tract at 26 time points throughout prepatency. The parasite had 5 asexual generations before oocyst formation that were located from the mid-jejunum to the mid-rectum and in the ceca. Sporulation of oocysts suspended in potassium dichromate at room temperature (22 C) occurred within 24 hr. Oocysts (n = 50) averaged 21.8 by 18.6 μm and featured a polar granule; sporocysts (n = 50) averaged 10.9 by 7.1 μm and possessed a Stieda body, sub-Stieda body, sporozoite refractile bodies, and sporocyst residuum. Comparisons with described Eimeria spp. infecting partridges suggest that the biological features of this pathogenic species are unique; similarly, sequences from both mitochondrial and nuclear loci support the naming of this new Eimeria species.