Morphological and molecular characterization of a new species of Schneider, 1881 (Apicomplexa: Eimeriidae) from the western wattlebird Gould in Western Australia.

A new coccidian species, n. sp., from the western wattlebird Gould in Western Australia is described and characterised molecularly. Microscopic analysis of a faecal sample identified subspheroidal oöcysts measuring 27-34 × 26-31 (30.6 × 29.4) μm ( = 20), with a length/width (L/W) ratio of 1.0-1.1 (1.0). Oöcysts have a bi-layered wall, 0.9-1.2 (1.0) μm thick; the outer layer is smooth, representing 2/3 of total thickness. Micropyle and oöcyst residuum are both absent, but a polar granule is present. Sporocysts are ovoidal, 17-19 × 10-12 (18.3 × 10.7) μm, with a L/W ratio of 1.6-1.8 (1.7) and occupying about 21% of the area (each one) within the oöcyst. Stieda body is flattened to rounded, measuring on average 0.9 × 1.8 μm; sub-Stieda body is rounded to rectangular, measuring on average 1.5 × 2.6 μm; para-Stieda body is absent. Sporocyst residuum has an irregular shape consisting of numerous granules and appears membrane-bound. Sporozoites are vermiform 12.8 × 3.0 μm on average, with prominent striations at the more pointed end and two refractile bodies below striations. Segments of three gene loci (18S rRNA, 28S rRNA and 1) were sequenced and . n. sp. exhibited 99.6% genetic similarity to Yang, Brice, Berto & Ryan, 2021 at the 18S rRNA gene locus, 99.8% genetic similarity to Yang, Brice & Ryan, 2014 and shared a 98.1% genetic similarity with Yang, Brice, Jian & Ryan, 2016 at the 1 gene locus. Morphological and molecular data support the distinct species status of the new species.