Rana Linnaeus 1758

Duszynski, Donald W., Bolek, Matthew G. & Upton, Steve J., 2007, Coccidia (Apicomplexa: Eimeriidae) of amphibians of the world, Zootaxa 1667 (1667), pp. 1-77 : 44-46

Host genus Rana Linnaeus 1758

(43 spp.)

Eimeria ranae ( Dobell 1908) Dobell 1909 ( Fig. 29)

Synonym: Cytospermium ranae Rivolta 1878 ; Coccidium ranae Dobell 1908 .

Type host: Rana temporaria L. 1758, Grass frog .

Other hosts: Pelophylax esculenta (L. 1758), Pool frog.

Type locality: EUROPE: England, Cambridge .

Geographic distribution: EUROPE: England, Germany.

Description of sporulated oocyst: Oocyst shape: spheroidal to ovoidal; number of walls: 1; wall thickness: “thin;” wall characteristics: smooth; L x W: 18–22 x 18–22; L/W ratio: 1.0; M and PG: absent; OR: present; OR characteristics: spheroidal mass composed of large granules (line drawing). Distinctive features of oocyst: very thin, single-layered wall that collapses around sporocysts or disintegrates releasing the sporocysts.

Description of sporocyst and sporozoites: Sporocyst shape: spindle-shaped with both ends tapering to a point; L x W: 14 x 7; L/W ratio: 2.0; SB: present as a small, nipple-like structure at 1 end of sporocyst; SSB: absent; PSB: present as a small, nipple-like structure at opposite end of sporocyst (see Remarks); SR: present; SR characteristics: spheroidal body composed of coarse granules between SZ; SZ: longer than sporocyst with their ends curled over one another; an indistinct N lies in the middle of each SZ. Distinctive features of sporocyst: presence of both SB and PSB, giving the sporocyst a strong resemblance to those of Monocystis spp.

Prevalence: ~15% of all R. temporaria ( Dobell 1909) .

Sporulation: Unknown; however, Dobell (1909) stated that it usually occured in the gut lumen of the lower small intestine and the large intestine (see Remarks).

Prepatent and patent periods: Unknown.

Site of infection: Unknown; however, Dobell (1909) speculated, “It appears most probable that schizog-

ony (= merogony) takes place in the small intestine in the upper part and is completed before any of the parasites proceed to spore formation.”

Endogenous stages: Unknown. Dobell (1909) said that he repeatedly examined the intestinal epithelium, the liver, and the kidneys of frogs that were passing “spores” (oocysts and/or sporocysts) and those that were uninfected and never could find any endogenous stages.

Pathology: Unknown.

Materials deposited: None.

Remarks: Dobell (1908, 1909) found this species in R. temporaria near Cambridge and Munich and once in P. esculenta near Munich. He originally named it in 1908, but provided no mensural data and no line drawing, thus creating a species inquirenda. In 1909 he gave a more detailed description, providing both measurements and a line drawing. The most interesting and/or disturbing aspect about his species description is the structure of the sporocysts, which strongly resemble the spores of Monocystis spp. However, Dobell (1909) said that he carefully followed the sporulation process and watched the sporocysts change from what he called “oval” (his Fig. 95) to spindle-shaped (his Figs. 96, 97), with a nipple-like structure on each end. He was clearly aware of the existence of Monocystis spores because he said, “Their resemblance to the spores of Monocystis is often very striking in early stages of development. As I have already noted (p. 206), these spores are not uncommon in frogs. Of course, when fully formed the octozoic Monocystis spores cannot possibly be mistaken for the dizoic spores of the Eimeria .” If his description is accurate, this is 1 of only 2 amphibian coccidia to possess a PSB (the other being E. spherica from Mesotriton alpestris , from France). The other interesting aspect of Dobell’s (1909) work is that he stated he always encountered sporogony to occur in the lower end of the frog’s gut about the posterior half of the small intestine, together with the large intestine. However, the timeline he gives for sporulation to occur is as follows: unsporulated oocyst to 4 sporoblast stage, 12–20 h; sporoblasts into spores, 20 h; development of the “sporal residuum,” 6–7 h; from the sporal residuum to sporozoite formation, development proceeds more slowly, but no time is given. Thus, sporulation, which he says takes place in the lower small intestine and the large intestine takes, minimally, 38+ h. Our observations on ranid and other anurans maintained in the laboratory indicate that, unless they are fed, they may not defecate for up to a week. Taken together these data suggest that the observation of fully sporulated oocysts in the feces of anurans may not indicate that their development is endogenous and the only way to document endogenous development may be by documenting fully sporulated oocysts in infected host cells. Walton (1949a, b) lists E. ranae as a parasite of P. esculenta (1949a) and R. temporaria (1949b) , both from Europe, but provides no other information.

Isospora neos Yakimoff and Gousseff 1936 a , b ( Fig. 30)

Type host: Rana arvalis Nilsson 1842 , Moor frog.

Other hosts: None reported to date.

Type locality: EUROPE: Belarus, Vitsyebskaya Voblasts , district of Polock .

Geographic distribution: EUROPE: Belarus, Poland.

Description of sporulated oocyst: Oocyst shape: ovoidal or spheroidal to subspheroidal; number of walls: 1 (line drawing); wall characteristics: transparent, smooth, and delicate; L x W: spheroidal, 23.7 (22– 27) or subspheroidal, 26 x 22.4 (23–29 x 20–24); L/W ratio: 1.0 or 1.1; M, OR, PG: absent. Distinctive features of oocyst: none.

Description of sporocyst and sporozoites: Sporocyst shape: ovoidal, slightly pointed at 1 end; L x W: 12.6–13.6 x 7.2–10.8; L/W ratio: unknown; SB, SSB, PSB: all absent (line drawing); SR: absent (original description) or present (Kazubski & Grabda-Kazubska 1973); SR characteristics: a membrane-bound ball of large granules (line drawing), 9–11 x 6–7. Distinctive features of sporocyst: the membrane-bound SR that is always on 1 side of the sporocyst.

Prevalence: 1 of 38 (<3%) (Kazubski & Grabda-Kazubska 1973).

Sporulation: Exogenous, but sporulation begins in transit down the intestine and is completed in 24 h at room temperature.

Prepatent and patent periods: Unknown.

Site of infection: Posterior half of the small intestine (Kazubski & Grabda-Kazubska 1973).

Endogenous stages: Unknown.

Pathology: Unknown.

Materials deposited: None.

Remarks: This species seems most similar to I. brumpti ( Fig. 7) reported from a Pseudepidalea viridis in Syria. However, the oocysts of I. brumpti are longer and, thus, have a larger L/W ratio. Kazubski and Grabda- Kazubska (1973) redescribed I. neos as oval, 21–22 x 19–20 with a delicate wall that bursts after several hours. Their sporocysts were oval or slightly spindle-shaped, 16.2 x 12.8 (15–18.5 x 12–14.5), with a large granular SR (9–11 x 6–7) that was always on one side of the sporocyst and the SZ they measured were banana-shaped, 14–15 x 3–3.5. The main difference between the original description ( Yakimoff & Gousseff 1936b) and the redescription by Kazubski and Grabda-Kazubska (1973) was that the latter authors described a large, apparently membrane-bound (line drawing) SR, not reported by Yakimoff and Gousseff (1936b). However, given the same host species and the geographic proximity of the hosts in both descriptions, they suggested that Yakimoff and Gousseff (1936b) simply missed it by saying, “its absence in the sporocysts seems to be hardly probable.” Kazubski and Grabda-Kazubska (1973) also noted that unsporulated oocysts, 17–19 wide, were smaller than sporulated oocysts.