Morphological and molecular characterization of Eimeria haematopusi n. sp. (Apicomplexa: Eimeriidae) in an Australian Pied Oystercatcher (Haematopus longirostris) (Aves: Charadriiformes)

Syst Parasitol (2024) 101:40 https://doi.org/10.1007/s11230-024-10152-5 Morphological and molecular characterization of Eimeria haematopusi n. sp. (Apicomplexa: Eimeriidae) in an Australian Pied Oystercatcher (Haematopus longirostris) (Aves: Charadriiformes) Jill M. Austen · Belinda Brice · Dandan Liu · Huimin Gao · Bruno P. Berto · Alireza Zahedi · Aileen Elloit · Rongchang Yang Received: 18 December 2023 / Accepted: 26 January 2024 / Published online: 13 May 2024 © Crown 2024 Abstract 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 J. M. Austen · A. Zahedi · A. Elloit · R. Yang (*) School of Agricultural Sciences, Murdoch University, Murdoch, WA 6150, Australia e-mail: B. Brice Kanyana Wildlife Rehabilitation Centre, 120 Gilchrist Road, Lesmurdie, WA 6076, Australia D. Liu Jiangsu Co‑innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, Jiangsu, People’s Republic of China H. Gao Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 05005, People’s Republic of China B. P. Berto Departamento de Biologia Animal, Instituto de Ciências Biológicas e da Saúde, Universidade Federal Rural do Rio de Janeiro, BR‑465 km 7, Seropédica, RJ 23897‑000, Brazil 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 bilayered 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 Vol.: (0123456789) 13 40 Page 2 of 9 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. Introduction The Australian pied oystercatcher (Haematopus longirostris) is a medium-sized black and white wading bird with distinctive features including a bright orange-red bill, red legs, red eye rings and eyes (Pizzey and Knight, 2007). It is found along much of the Australian and Tasmanian coastline, the south coast of New Guinea and the coasts of the Aru and Kai Islands in Indonesia (Hockey et al., 2020). The Australian pied oystercatcher belongs to the Order Charadriiformes and the Suborder Charadrii (waders) and is a member of the Haematopodidae family. There are 12 species of oystercatcher in the Haematopus genus (Winkler et al., 2020) that include the pied oystercatcher (H. longirostris Vieillot), Eurasian oystercatcher (H. ostralegus Linnaeus), South Island oystercatcher (H. finschi Martens), Chatham oystercatcher (H. chathamensis Hartert), variable oystercatcher (H. unicolor Forster), sooty oystercatcher (H. fuliginosus Gould), American oystercatcher (H. palliatus Temminck), African oystercatcher (H. moquini Bonaparte), Canarian oystercatcher (H. meadewaldoi Bannerman), blackish oystercatcher (H. ater Vieillot), magellanic oystercatcher (H. leucopodus Garnot) and the black oystercatcher (H. bachmani Audubon) (Winkler et al., 2020). Taxonomical classification places the oystercatchers genetically closest to the ibisbill (Ibidorhynchidae). Together, they form a clade that is most closely related to the avocets and stilts (Recurvirostridae) (Winkler et al., 2020). Eimeria spp. are the eimeriid coccidia with the greatest parasitic diversity, being found in all groups of vertebrates, in addition to invertebrates (Duszynski, 2021). Isospora spp. are also widely diverse, but are predominantly found in Passeriformes, but also in other orders such as Strigiformes and Struthioniformes (Berto et al., 2011; 2023; Medina et al., 2019; Woodyard et al., 2019; Coker et al., 2023). Within the Charadriiformes, fewer than 22 Vol:. (1234567890) 13 Syst Parasitol (2024) 101:40 species of Eimeria (the largest of the Eimeriidae) have been documented to infect members of this order. The Eimeria species previously documented include Eimeria burchinici (Dzerzhinskii and Kairooaev, 1989) in a stone curlew (Burhinus oedicencus Linnaeus), six Eimeria species from plovers (Family Charadriidae), five Eimeria species from the sandpipers (Family Scolopacidae), Eimeria stercorariae Galli-Valerio, 1940 from a parasitic jaeger (Stercorarius parasiticus (Linnaeus)), eight Eimeria species from gulls and terns (Laridae family) and Eimeria fraterculae Leighton and Gajadhar, 1986 from a common puffin (Fratercula arctica (Linnaeus)) (Duszynski et al., 2001). To date, there is only one species of Eimeria described from unsporulated oocysts from the Haematopus genus, namely Eimeria haematopi, isolated from the kidneys of a Eurasian oystercatcher (H. ostralegus) (Gottschalk and Prange, 2011). In a later study by Siebert et al. (2012) the detection of coccidian infection in histological kidney sections of two Eurasian oystercatchers (H. ostralegus) was evident during the investigation of the health status of seabirds along the North Sea coast of Germany. Unfortunately, no oocysts were isolated or characterized from the study. In this study, we characterize a new species of Eimeria from a wild Australian pied oystercatcher (H. longirostris), both morphologically and genetically, and propose the species name Eimeria haematopusi n. sp. Materials and methods Sampl (...truncated)