A new Caryospora coccidian species (Apicomplexa: Eimeriidae) from the laughing kookaburra (Dacelo novaeguineae)

摘要

A new Caryospora coccidian species is described from the laughing kookaburra (Dacelo novaeguineae). Sporulated oocysts (n = 30) are ovoid in shape with a smooth, colourless, bilayered oocyst wall and measure 31.4 x 29.3 (30.0-32.0 x 28.0-31.0) mu m with a shape index of 1.1. Oocysts contain one spheroidal to subspheroidal sporocyst, 21.2 x 20.6 (20.0-24.0 x 20.0-21.0) mu m. A spheroidal shaped sporocyst residuum is present; micropyle, Stieda, substieda and parastieda bodies are absent. Vermiform sporozoites (n = 8) are arranged either parallel or randomly in the sporocyst, measuring 17.0 x 4.8 (16.0-18.0 x 4.0-6.0) mu m, with a L/W ratio of 3.5. There is a large spheroidal, posterior refractile body in the middle of the sporozoite. Morphologically, this new species is most similar to Caryospora. The prevalence of this parasite was 6.7% in birds sampled in the morning and 33.3% from those sampled after midday. Further molecular characterisation was conducted at two loci; the 18S and 28S ribosomal RNA (rRNA). At the 18S locus, the new species of Caryospora was most closely related to Besnoitia besnoiti (99.2% similarity) and Hammondia triffittae (98.8% similarity). Although, no 28S partial sequences from Caryospora were available in GenBank, the highest similarity was with B. besnoiti (91.3%). Based on morphological and molecular data, this coccidian parasite is a new species that to date has not been reported. The new coccidian parasite is named Caryospora daceloe n. sp. after its host D. novaeguineae (the laughing kookaburra).