Isospora carliae sp. n. is described from the blue-throated rainbow skink Carlia rhomboidalis (Peters), from Daintree Forest, North Queensland, Australia. Oocysts are ellipsoidal, 16.8-21.0 × 12.6-15.4 µm in size, with their two sporocysts, 9.0-14.0 × 7.0-9.24 µm in size, positioned along the wide axis. Sporozoites contain a distinct refractile body and are accompanied by a residuum. All endogenous development occurs within the host-cell nucleus. Nuclei are sometimes invaded by several merozoites, but only infections by a single parasite persist. Nuclei lodging meronts, mature microgamonts and premature macrogamonts have an elongate shape. Some meronts exhibit a membrane-bound cytoplasmic inclusion that contains many micronemes.