Synonyms: Eimeria neglecta Noller, 1920.

Type host: Tadpoles of Pelophylax esculenta (L., 1758), Pool frog.

Other hosts: Tadpoles of Pelophylax ridibundus (Pallas 1771), Marsh frog; possibly tadpoles of Pelophylax lessonae (Camerano 1882), Little water frog; possibly tadpoles of Rana temporaria L. 1758, Grass frog.

Type locality: EUROPE: Germany, near Hamburg.

Geographic distribution: EUROPE: Germany, Hungary.

Description of oocyst: Oocyst shape: round, oocysts are ocasionally in groups of 2 or 3 enclosed in yellow bodies; number of walls: 1; wall thickness: thin; wall characteristics: fragile and smooth; L x W: 10.6 (8.5-12.5); L/W ratio: 1.0; M: absent; OR: absent; PG: absent. Distinctive features of oocyst: very thin, single-layered and oocysts are often carried with the intestinal epithelial cell when these are shed into the lumen.

Description of sporocysts and sporozoite: Sporocyst shape: ovoidal (Noller, 1920) to ellipsoidal (Molnar, 1995), with 1 side slightly flattened, with distinct longitudinal sutures (see Remarks); L x W: 8.8 x 4.8 (6.5-10 x 4-6); L/W ratio: 1.8; SB: absent; SSB: absent; PSB: absent; SR: present; SR characteristics: spheroidal to subspheroidal body composed of large granules (line drawing), 5-7.5 x 3-4 in young oocysts and spheroidal, ~1 in older oocysts; SZ: vermiform with one end reflexed, 8.2 x 1.8 (6-10 x 1.5-2) with indistinct, centrally located N. Distinctive features of sporocysts: very thin wall with one side slightly flattened and with distinct longitudinal sutures, characteristic of the genus; recurved SZ.

Prevalence: Unknown for type host in Germany; 19 of 38 (50%) P. ridibundus; 7 of 10 (70%) P. esculenta in Hungary (Molnár 1995).

Sporulation: Endogenous.

Prepatent and patent periods: Unknown.

Site of infection: Epithelial cells of the intestine.

Endogenous development: Nöller (1920) found merogony to occur in the epithelial cells of the tadpole, but not in those of the adult. Molnár (1995) indicated that meronts contained 8–16 merozoites arranged in parallel. Meronts, gamonts, and immature oocysts were observed both in apical and basal cytoplasm of the epithelial cells.

Materials deposited: None.

Remarks: This was the first coccidium described from tadpoles (Nöller 1920) and to date is only the second named species of Goussia known from amphibians. The description given above is a composite from Nöller’s (1920) original description (which was grossly inadequate, but did include a crude line drawing) and Molnár’s (1995) re-description. Finally, Walton (1949b), in an abstract, mentioned G. (E.) neglecta as a parasite of R. temporaria from Europe, but provided no other information. Molnár (1995) indicated that the oocysts of this species consisted of 2 halves joined by a suture and because of this observation transferred Eimeria neglecta to the genus Goussia. However, his line drawing of the oocyst does not show the 2 halves, and we suspect that he meant that the sporocysts contained 2 halves joined by a suture which is the characteristic feature of the genus Goussia and this was misstranslated from Hungarian to English. Both Nöller (1920) and Molnár (1995) reported G. neglecta in tadpoles of Pelophylax spp. and possibly tadpoles of Pelophylax lessonae, but not adult frogs. Molnár (1995) noted that the highest prevalence of infection was observed during July in tadpoles that had hindlimbs, but that the prevalence was lower in tadpoles with hindlimbs and emerged forelimbs and lowest in those with no limbs. Sporulated oocysts were found in mucus and feces and in groups of 2 or 3 enclosed in yellow bodies. Molnár (1995) speculated how the oocysts of G. neglecta might survive after leaving the tadpole, given the very fragile nature of their oocyst and sporocyst walls; he suggested the species might overwinter as sporozoites in tubificid oligiochaetes as was shown for G. carpelli in the common carp (Steinhagen & Körting 1990). Molnár (1995) also mentioned seeing developmental stages of another coccidium in the N of the epithelial cells in the frogs he examined, but that these seem to represent another species. Recently Jirku and Modrý (2006b) reported a Goussia sp. similar in morphology to G. neglecta from a forest pond at Zajetchee potok, Brno, Czeck Republic in 23 of 45 (51%) tadpoles of the agile frog, Rana dalmatina, Fitzinger In Bonaparte, 1839. Because measurements of the sporocysts of their isolate differed slightly, but overlapped in range with G. neglecta from the original description by Nöller (1920) and as reported by Molnár (1995), they took the conservative approach and refer to their isolate as a species of Goussia. Importantly, their examinations of tadpoles indicated that they found developmental stages of Goussia sp. in the intestine, and fully sporulated oocysts in the intestine and the sinuses of the liver. They allowed tadpoles of R. dalmatina to metamorphose to assess the fate of Goussia infections in these hosts. All juvenile and subadult frogs which metamorphosed in the laboratory and were examined 2 wk to 15 mo after metamorphosis contained oocysts of Goussia sp. in the liver, but not in the intestine. Only individual or clusters of oocysts were observed in the liver, and these were not enclosed by yellow bodies or macrophages. This study was the first to demonstrate Goussia sp. infections in an extraintestinal location in an amphibian host. The authors suggested that the extraintestinal oocysts of amphibian Goussia sp. in metamorphosed frogs may serve as a reservoir for colonization of tadpoles at new breeding sites or when ponds dry up. They suggested that oocysts of Goussia sp. in the liver of adult frogs are not likely to leave the host by the feces, and tadpoles may become infected by consuming dead frogs with oocysts in their liver.