Morphological and molecular description of a new species of Isospora (Apicomplexa) from a New Holland honeyeater (Phylidonyris novaehollandiae)

• Published in: Parasitology international 2021-08, Vol.83, p.102348-102348, Article 102348
• Main Authors: Yang, Rongchang, Brice, Belinda, Berto, Bruno P., Ryan, Una
• Format: Article
• Language: English
• Subjects: 18S RNA; 28S RNA; COI; Isospora; New Holland honeyeater
• ISSN: 1383-5769; 1873-0329
• DOI: 10.1016/j.parint.2021.102348

A new Isospora species is described from New Holland honeyeaters (Phylidonyris novaehollandiae). Sporulated oocysts (n = 25) were characterised as subspheroidal, 29–32 × 28–31 (29.8 × 29.4); length/width (L/W) ratio 1.01–1.02 (1.01). Wall bi-layered, 1.3–1.6 (1.5) thick, outer layer smooth, c.2/3 of total thickness. Micropyle and oocyst residuum absent, but usually two polar granules are present. Sporocysts (n = 25) ovoidal, 18–19 × 12–14 (18.4 × 12.3); L/W ratio 1.42–1.53 (1.50). Stieda body present, flattened, c.0.5 deep × 2.5 wide; sub-Stieda present, rounded, c.2.5 deep × 3.5 wide; para-Stieda body absent; sporocyst residuum present, usually a distinctly irregular body consisting of numerous small granules that appear to be membrane-bound. Sporozoites vermiform, with robust anterior and posterior refractile bodies. Molecular characterization was conducted at the 18S and 28S ribosomal RNA and the mitochondrial (mt) cytochrome oxidase (COI) loci. Phylogenetic analysis of genomic 18S and mt COI sequences indicated that Isospora phylidonyrisae n. sp. was genetically similar to Isospora coronoideae, isolated from an Australian raven (Corvus coronoides) in Western Australia, with a 99.3% and 98.4% homology, respectively. The 28S rRNA sequence was most similar to Isospora anthochaerae (KF766053) and Isospora manorinae (KT224381), both with a 98.2% genetic similarity. Based on morphological and genetic data, this isolate is a new species of Isospora, which is named Isospora phylidonyrisae n. sp. after its host. [Display omitted] •Description of I. phylidonyrisae n. sp. in a New Holland Honeyeater.•Morphology study: Unique to any of the reported Isospora spp..•Genetic study: 99.3% and 99.4% similar to I. coronoideae at 18S and mtCOI locus, respectively.