Isospora habiae n. sp. (Chromista: Apicomplexa: Eimeriidae) from Red-crowned Ant-tanagers Habia rubica (Vieillot, 1817) (Aves: Passeriformes: Cardinalidae) in South America

The Red-crowned Ant-tanager Habia rubica (Vieillot, 1817) is a forest-dependent passerine that inhabits the understory of humid forests and is widely distributed throughout Central and South America, extending northward into Mexico. Wild birds may host a broad diversity of parasites, among which coccidia constitute one of the most species-rich and taxonomically complex groups. Within this context, the present study reports a new species of Isospora Schneider, 1881 parasitizing Red-crowned Ant-tanagers captured in Itatiaia National Park, a protected area of high ecological vulnerability in southeastern Brazil. The oocysts of Isospora habiae Ortúzar-Ferreira & Berto n. sp. are subspheroidal to ovoidal, measuring on average 24 × 23 μm. A micropyle is absent. An oocyst residuum is present, whereas a polar granule is not observed. Sporocysts are ovoidal, with a mean size of 17 × 12 μm. Stieda and sub-Stieda bodies are present. A sporocyst residuum occurs among the vermiform sporozoites, which exhibit striations, refractile bodies, and a nucleus. This morphology clearly differs from that of other Isospora spp. previously recorded in hosts of the family Cardinalidae. Molecular identification was carried out through amplification and sequencing of three mitochondrial loci. In the molecular and phylogenetic analyses based on concatenated sequences of these loci, I. habiae n. sp. formed a monophyletic lineage and exhibited the highest similarity values with Isospora spp. infecting hosts of the families Cardinalidae and Sturnidae. Based on the combined morphological and molecular evidence obtained from oocysts recovered from H. rubica, I. habiae n. sp. is established here as new to science. It represents the third Isospora sp. documented from a cardinalid host and the first nominal species within this family to receive molecular characterization using mitochondrial gene sequences.