Belinda Brice

Description:We describe and characterize a new Isospora species from the Singing honeyeater (Gavicalis virescens) in Western Australia, both morphologically and molecularly. Microscopic analysis of a fecal sample identified 25 ellipsoidal oocysts, measuring 21-25 × 18-20 μm (mean 23.4 × 18.7 μm), with a length/width (L/W) ratio of 1.2-1.3 (mean 1.25). The oocyst wall is bilayered and ~1.0 μm thick, with a smooth outer layer making up about two-thirds of the thickness. A micropyle cap, measuring ~2.0 × 4.5 μm, is present as a curved protrusion on the outer layer. The micropyle itself is ~4.5 μm wide. The oocysts lack a residuum but contain 1-2 polar granules. The 25 ellipsoidal sporocysts measured 14-15 × 8-9 μm (mean 14.1 × 8.7 μm) with an L/W ratio of 1.6-1.7 (mean 1.62). The Stieda body is flattened (~0.5 × 1.5 μm), the sub-Stieda body is rounded (~1.5 × 2.5 μm), and the para-Stieda body is absent. The sporocyst residuum, composed of clustered spherules, is ~3.5 × 3.5 μm. Sporozoites contain anterior and posterior refractile bodies and a nucleus. Molecular analysis of the 18S rRNA, 28S rRNA, and COI gene loci showed a 99.5% genetic similarity to Isospora neochmiae at the 18S rRNA locus and 99.2% and 97.7% similarities to Isospora manorinae at the 28S rRNA and COI loci, respectively. Phylogenetic analysis confirmed that the new species is closely related to I. manorinae. Based on these data, we propose this isolate as a new species, Isospora virescensae n. sp.

Description:We describe and characterize a new Isospora species from the black-faced cuckoo-shrike (Coracina novaehollandiae) in Western Australia, using both morphological and molecular approaches. Microscopic analysis of a fecal sample revealed 20 ellipsoidal oocysts, which are subspheroidal to ovoid, measuring 40-43 × 39-41 μm (mean 41.4 × 39.6 μm) with a length/width (L/W) ratio of 1.0-1.1 (mean 1.04). The oocyst wall is bi-layered (~1.5 μm thick), with a smooth outer layer constituting approximately two thirds of the total thickness. A micropyle is present, characterized by a slight invagination of the inner layer (~6.0 μm wide), but no micropyle cap is observed. Both the oocyst residuum and polar granule are absent. Sporocysts (n = 20) are ellipsoidal, measuring 23-24 × 13-14 μm (mean 23.3 × 13.4 μm) with an L/W ratio of 1.7-1.8 (mean 1.74). A flattened to knob-like Stieda body (~1.5 × 3.0 μm) is present, while sub-Stieda and para-Stieda bodies are absent. The sporocyst residuum is composed of granules clustered by a membrane, forming an irregular shape (~12.0 × 8.0 μm). Sporozoites exhibit anterior and posterior refractile bodies and a nucleus. Molecular analyses of the 18S rRNA, 28S rRNA, and COI gene loci demonstrated that this species forms a distinct clade with Isospora serinuse in phylogenetic trees based on all three loci. It shares genetic similarities with I. serinuse of 98.8%, 93.7%, and 98.9% for the 18S rRNA, 28S rRNA, and COI loci, respectively. Phylogenetic analysis confirms that this new species is closely related to I. serinuse. Based on these findings, we propose this isolate as a new species, Isospora coracinae n. sp. This is the first coccidian species identified from the Campephagidae family in Australia.

Description:A novel Eimeria Schneider, 1875 species is described from an Australian pied oystercatcher Haematopus longirostris Vieillot, in Western Australia. The pied oystercatcher was admitted to the Kanyana Wildlife Rehabilitation Centre (KWRC), Perth, Western Australia in a poor body condition, abrasion to its right hock and signs of partial delamination to its lower beak. Investigation into potential medical causes resulted in a faecal sample being collected and screened for gastrointestinal parasites. Unsporulated coccidian oocysts were initially observed in the faeces and identified as Eimeria upon sporulation. The sporulated oocysts (n = 20) are ellipsoidal, 20-21 × 12-13 μm in shape and have thick bi-layered walls which are c.2/3 of the total thickness. Micropyle is present, robust and protruding, and occasionally has a rounded polar body attached to the micropyle. Within the oocyst, a residuum, in addition, two to five polar granules are present. There are four ellipsoidal sporocysts 9-11 × 5-6 μm with flattened to half-moon shaped Stieda bodies. Sub-Stieda body and para-Stieda body are absent. The sporocysts contain sporocyst residuums composed of a few spherules scattered among the sporozoites. Within the sporozoites, anterior and posterior refractile bodies are present, but the nucleus is indiscernible. To further characterise the novel Eimeria species from H. longirostris, molecular analysis was conducted at the 18S ribosomal RNA locus, using PCR amplification and cloning. Two cloned sequences from the novel Eimeria were compared with those from other Eimeria spp. with the highest genetic similarity of 97.6% and 97.2% from Clone 1 and 2, respectively with Eimeria reichenowi (AB544308) from a hooded crane (Grus monacha Temminck) in Japan. Both sequences grouped in a clade with the Eimeria spp. isolated from wetland birds, which include Eimeria paludosa (KJ767187) from a dusky moorhen (Gallinula tenebrosa Gould) in Western Australia, Eimeria reichenowi (AB544308) and Eimeria gruis (AB544336) both from hooded cranes. Based on the morphological and molecular data, this Eimeria sp. is a new species of coccidian parasite and is named Eimeria haematopusi n. sp. after its host H. longirostris.

Description:A novel Eimeria sp. from a captive-bred bilby (Macrotis lagotis Reid, 1837) has been identified in Western Australia. The bilby was bred at the Kanyana Wildlife Rehabilitation Centre, Perth, as part of the National Bilby Recovery Plan. Oocysts (n = 31) irregular blunt ellipsoidal, 17-18 × 11-12 (17.2 × 11.3); length/width (L/W) ratio 1.4-1.5 (1.5). Wall bi-layered, 0.8-1.0 (0.9) thick, outer layer smooth, c.2/3 of total thickness. Micropyle barely discernible. Oocyst residuum is absent, but 2-3 small polar granules are present. Sporocysts (n = 31) ovoidal, 7-8 × 5-6 (7.8 × 5.7); L/W ratio 1.3-1.4 (1.4). Stieda, sub-Stieda and para-Stieda bodies absent or indiscernible; sporocyst residuum present, usually as an irregular body consisting of numerous granules that appear to be membrane-bound or sometimes diffuse among sporozoites. Sporozoites vermiform with a robust refractile body. Further molecular characterization was conducted on the sporulated oocysts. At the 18S locus, it sat in a large clade of the phylogenetic tree with two isolates of Eimeria angustus from quendas (Isoodon obesulus Shaw, 1797) and the Choleoeimeria spp. It shared the highest identity with E. angustus (KU248093) at 98.84%; at the COI gene locus, it was unique and most closely related to Choleoeimeria taggarti, which is hosted by another species of marsupial, the yellow-footed antechinus (Antechinus flavipes flavipes), with 90.58% genetic similarity. Based on morphological and molecular data, this isolate is a new species and named as Choleoeimeria yangi n. sp.

Description:A new coccidian species, Isospora elliotae n. sp., from the Australian magpie Gymnorhina tibicen (Latham, 1801) in Western Australia, is described and characterized morphologically and molecularly. Microscopic analysis of a faecal sample identified subspheroidal oocysts (n = 20), 20-22 × 18-20 (20.7 × 18.7); length/width (L/W) ratio 1.05-1.14 (1.10). Wall bi-layered, 1.0-1.3 (1.2) thick, outer layer smooth, c. 2/3 of total thickness. Micropyle and oocyst residuum absent, but usually two polar granules are present. Sporocysts (n = 28) ovoidal, 12-13 × 9-11 (12.6 × 9.7); L/W ratio 1.22-1.35 (1.30). Stieda body present, flattened to half-moon-shaped, c. 0.5 deep × 2.0 wide; sub-Stieda indistinct or barely discernible, c. 1.0 deep × 2.5 wide; para-Stieda body absent; sporocyst residuum present, composed of granules dispersed among the sporozoites. Sporozoites vermiform, with anterior and posterior refractile bodies and nucleus. Segments of three gene loci (18S rRNA, 28S rRNA and COI) were sequenced and I. elliotae n. sp. exhibited 99.8% genetic similarity to Isospora sp. MAH-2013a (KF648870) followed by 99.7% genetic similarity to Isospora neochmiae (Yang, Brice & Ryan, 2016) (KT224380) at the 18S rRNA gene locus. It shared 97.0% genetic similarity with an unnamed Isospora sp. (AY283852) at the 28S rRNA gene locus and it also shared the highest genetic similarity of 99.8% with the unnamed Isospora sp. from an American crow (OL999120) at the COI gene locus. Based on morphological and molecular data, this isolate is a new species named as I. elliotae n. sp.