Springer 2006
Systematic Parasitology (2006) 65:73–76 DOI 10.1007/s11230-006-9040-z
Eimeria lokuma n. sp. (Apicomplexa: Eimeriidae), a new coccidium from the African helmeted turtle Pelomedusa subrufa (Lace´pe`de) (Testudines: Pelomedusidae) Pavel Sˇiroky´1,*, Martin Kamler2 & David Modry´2,3 1
Department of Biology and Wildlife Diseases, University of Veterinary and Pharmaceutical Sciences, Palacke´ho 1-3, CZ-612 42 Brno, Czech Republic 2 Department of Parasitology, University of Veterinary and Pharmaceutical Sciences, Palacke´ho 1-3, CZ-612 42 Brno, Czech Republic 3 Institute of Parasitology, Academy of Sciences of the Czech Republic, Branisˇovska´ 31, CZ-370 05 Cˇeske´ Budeˇjovice, Czech Republic Accepted for publication 17th November, 2005
Abstract Coprological examination of nine African helmeted turtles Pelomedusa subrufa from Kenya revealed the presence of a new coccidium belonging to Eimeria Schneider, 1875. Oo¨cysts of Eimeria lokuma n. sp. are spherical to sub-spherical, 13.6 (13–14.5) 13 (12–14) lm, lack a micropyle and a polar granule, but possess a granular oo¨cyst residuum. The sporocysts are elongate, oval to spindle-shaped and 8.3 (7.5–9.5) 4.4 (4–5) lm. The Stieda body is relatively low, flat and wide, and covered with a membranous, highly flexible, scarf-like structure which protrudes from its strengthened margins. The sporozoites possess two refractile bodies. Based on the presence of a Stieda body, the described species is classified as Eimeria (sensu stricto).
Introduction
Materials and methods
African helmeted turtle Pelomedusa subrufa (Lace´pe`de) is the most common semiaquatic turtle of sub-Saharan Africa (Iverson, 1992). It inhabits temporary marshes, creeks and rain holes in open country, seldom occurs in heavily forested areas and is commonly found on suitable sites from the coastal plain to upland savannas of 3,100 m elevation. Three subspecies have been described; however, more data are needed to assess their validity (Ernst & Barbour, 1989). Within the framework of a wider study on the diversity of reptilian parasites in East Africa, we had a chance to sample a group of nine P. subrufa from Kenya. Their subsequent examination revealed the presence of a new species of Eimeria Schneider, 1875, which is described and named in this paper.
Nine Pelomedusa subrufa were collected in September, 2003 at three localities in Kenya – South Horr (205¢48¢¢N, 3654¢43¢¢E, five turtles), northwards of Lake Baringo (043¢37¢¢N, 3601¢03¢¢E, a single turtle) and Kakamega forest (020¢56¢¢N, 3451¢56¢¢E, three turtles). Four specimens were placed separately in plastic boxes, where faecal samples were collected, whereas the remaining five turtles were killed by overdosing with barbiturates (Thiopental Spofa) and dissected for a complete parasitological inspection. The specimen from Lake Baringo was found moribund on a road, fatally injured by a car, then killed, dissected and sampled for later examination. Fresh faeces obtained from all of the turtles were placed in 2.5% aqueous (w/v) potassium dichromate (K2Cr2O7) solution, mixed thoroughly to allow sporulation and transported to our laboratory in
*Author for correspondence (E-mail:
[email protected])
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Figures 1–3. Eimeria lokuma n. sp. DIC micrographs of sporulated oo¨cysts. 1. Note granular sporocyst residuum (arrowhead). 2. Note oo¨cyst residuum (arrowhead). 3. Note membranous scarf-like structure covering Stieda body and protruding from its strengthened margins (arrowhead). Scale-bar: 10 lm
the Czech Republic. All samples were examined microscopically using concentration by flotation with modified Sheather’s sugar solution (specific gravity 1.3). Coccidian oo¨cysts were measured and photographed using an Olympus Provis AX-70 microscope with DIC optics. Measurements were made using a calibrated ocular micrometer and are reported throughout in micrometres, as the mean followed by the range in parentheses.
Results Coprological examination revealed the presence of oo¨cysts of a previously undescribed species of Eimeria in one of the nine turtles examined. This species is described below. Eimeria lokuma n. sp. Type-host: African helmeted turtle Pelomedusa subrufa, (Lace´pe`de) (Testudines: Pelomedusidae). Type-locality: Central Kenya, between Tangulbei and Lake Baringo (043¢37¢¢N, 3601¢03¢¢E). Type-specimens: Photosyntypes are deposited in Department of Parasitology, University of Veterinary and Pharmaceutical Sciences Brno, Czech Republic, No. R 91/05. Sporulation: Probably exogenous. Examined samples contained only fully-sporulated oo¨cysts. Prevalence: One of nine examined specimens of P. subrufa was infected. Etymology: The specific epithet ‘‘lokuma’’ is adopted from Masai language, which uses this
vernacular name both for freshwater turtles and land tortoises (Spawls et al., 2002); it is given, in accordance with International Code of Zoological Nomenclature (Article 31.1) as a noun in apposition (ICZN, 1999). Description (Figures 1–4) Oo¨cysts sub-spherical to spherical, 13.6 (13– 14.5) 13.0 (12–14) (n=22); shape-index (SI, length/width) 1.05 (1–1.17). Oo¨cyst wall smooth, colourless, bilayered, 0.7 (c.0.5–0.8) thick. Micropyle and polar granule absent; oo¨cyst residuum present, globular, 3 (2.5–4) 3.5 (3–4.5), composed of fine granular matter. Sporocysts elongate, oval to spindle-shaped, 8.3 (7.5–9.5) 4.4 (4–5) (n=24), with smooth, colourless sporocyst wall, c.0.2–0.3 thick; sporocyst SI 1.9 (1.6–2.13). Stieda body present as c.0.3–0.5 low flat and c.1.2–1.5 wide projection; substieda body not discernible. Membranous, highly flexible, scarf-like structure, covers Stieda body, protruding from its strengthened margins. Sporozoites elongate, lying head to tail within sporocyst; each bears spherical to subspherical refractile bodies (c.1.5–2 2–2.5) at both ends. Sporocyst residuum present, usually in form of granular matter scattered among sporozoites. Nucleus not discernible.
Discussion Despite the fact that the classification of coccidian parasites was traditionally based on the nature of
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Figure 4. Composite line drawing of a sporulated oo¨cyst of Eimeria lokuma n. sp. Scale-bar: 5 lm.
their life-cycle and the morphology of their oo¨cysts, recently published studies on coccidian molecular phylogeny has shed new light on this subject (Jirku˚ et al., 2000), highlighting out the importance of excystation structures. Using this morphological trait, reptilian coccidia with Eimeria-like tetrasporocystic oo¨cysts can be divided into two main groups, where species with a Stieda body are classified as Eimeria (sensu stricto). Then, E. lokuma n. sp. clearly belongs to the latter group. Fifty species of eimerian coccidia have been described and named from chelonian hosts (Upton et al., 1995; Lainson & Naiff, 1998; Hu˚rkova´ et al., 2000; Sˇiroky´ & Modry´, 2005). Such a diversity of species has lead to overlap in the limited number of morphological characters used as the principle diagnostic features (Duszynski & Wilber, 1997). Eimeria is traditionally considered to be highly host-specific, and both host systematics and geographical origin are commonly used tools in the taxonomy of this protistan group (Duszynski, 1986). No coccidian species has previously been described from chelonians of the Afro-tropical zoogeographical region. That is why we use in the following differential diagnosis the only four Eimeria species described and named from the sidenecked turtles of the suborder Pleurodira, despite the fact that all four parasitise Neotropical species of the family Pelomedusidae (sensu Gaffney & Meylan, 1988). The conspecificity of described E. lokuma n. sp. with coccidia from distantly related turtles of the suborder Cryptodira is unlikely.
Among the four Eimeria spp. known from pelomedusid hosts, three were described from the giant Amazon river turtle Podocnemis expansa (Schweigger). Compared to E. lokuma, E. lagunculata Lainson, Costa & Shaw, 1990 has longer oo¨cysts with a distinctive micropyle, lacks an oo¨cyst residuum, has larger sporocysts and lacks a Stieda body. E. mammiformis Lainson, Costa & Shaw, 1990 has much larger oo¨cysts and sporocysts, its oo¨cyst bears a prominent micropyle and an oo¨cyst residuum is lacking. The oo¨cyst of third species, E. podocnemis Lainson, Costa & Shaw, 1990, has a different shape-index (it is more elongate) and lacks an oo¨cyst residuum, the presence of a polar granule is a constant feature and sporocysts lack a Stieda body (Lainson et al., 1990). The fourth Eimeria species from pelomedusid hosts, E. peltocephali Lainson & Naiff, 1998, was described from the big-headed Amazon river turtle Peltocephalus dumerilianus (Schweigger); this is a huge coccidium easily distinguishable from all coccidia known from chelonians (Lainson & Naiff, 1998). E. lokuma also differs from all of the abovementioned species by the membranous structure covering the Stieda body. However, the possibility that this is an artefact of sporocyst degradation cannot be ruled out. Further studies of the fresh material are necessary to clarify origin of this unsual morphological trait. Based on the above-mentioned morphological differences, and on the geographical isolation of the host, we consider that the present eimeriid represents a species new to science.
Acknowledgements Research on the diversity of parasites of East African vertebrates was facilitated by the Biota East Africa project; we are deeply indebted to Jo¨rn Koehler for generous help. We also thank Richard Bagine (Kenyan Wildlife Service) for assistance and issuing necessary permits; Damaris Rotich and Patrick Malonza (National Museums of Kenya) helped with the organisation of the trip and kindly provided necessary laboratory facilities in Nairobi. Asad Anwar kindly offered accommodation in Nairobi and organised all the logistics of the expedition to northern Kenya. Finally, we thank inhabitants of South Horr and
76 Gatab villages for their help with the collecting of the animals. We are indebted to Olympus C&S for generous technical support. This study was supported by the grant No. 524/03/D104 of the Grant Agency of the Czech Republic.
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