Afternoon shedding of a new species ofIsospora(Apicomplexa) in the endangered Regent Honeyeater (Xanthomyza phrygia)

Abstract

SUMMARYThe Regent Honeyeater (Xanthomyza phyrigia) is an endangered Australian bird species. Breeding populations have been established at Australian zoos in support of re-introduction programmes. This species is the host of a new species ofIsospora(Apicomplexa). Oocysts are spherical, 25·8 (22·5–28·75) by 23·8 (20–26·25)μm with a colourless to pale yellow smooth wall undergoing rapid exogenous sporulation, 90% sporulated oocysts in 8 h at 20°C. Each oocyst contains 1 polar granule. Sporocysts are ovoid, 18·67 (17–19) by 9·49 (9–10)μm with a flat Stieda body and spherical substieda body devoid of a hyaline body. The asexual stages and sexual phase is within the enterocytes of the duodenum and jejunum. Faeces collected in the morning (AM,n=84) and in the afternoon (PM,n=90) revealed significant diurnal periodicity in oocyst shedding; 21% (18 of 84) of the AM were positive with the mean of 499 oocysts.g−1compared to the PM with 91% (82 of 90) bird faeces positive with the mean of 129 723 oocysts.g−1. Therefore, parasite checks for these birds should be carried out in the afternoon to obtain an accurate result. The ecological significance of the high parasite burden in captive birds requires further investigation and comparison to the wild counterparts.