Synonyms: Coccidium sphericum Schneider 1887; Cytophagus tritonis Steinhaus 1891, pro parte; Eimeria tritonis (Steinhaus 1891) Levine and Becker 1933; Karyophagus tritonis (Steinhaus 1891) von Wasielewski 1896; non Eimeria spherica of Matubayashi 1937; non Eimeria spherica Dogiel 1948, non Eimeria dogieli from fish.

Type host: Mesotriton alpestris (Laurenti, 1768), Alpine newt.

Other hosts: Triturus cristatus (Laurenti 1768), Crested newt; Lissotriton helveticus (Razoumovsky, 1789), Palmate newt; Lissotriton vulgaris (L. 1758), Common newt.

Type locality: EUROPE: France.

Geographic distribution: EUROPE: France.

Description of oocyst: Oocyst shape: spheroidal; number of walls: 2 (1 in line drawing); wall thickness: ~0.8; wall characteristics: outer smooth, inner thinner than outer; L x W: 35 (22-38); L/W ratio: 1.0; M: absent; OR: present; OR characteristics: large, spheroidal mass; PG: absent. Distinctive features of oocyst: spheroidal shape and very large OR.

Description of sporocysts and sporozoite: Sporocyst shape: ellipsoidal, slightly pointed at both ends; L x W: 12-15 x 6-7; L/W ratio: ~2.1; SB: may be present (line drawing); SSB: absent; PSB: may be present (line drawing); SR: present; SR characteristics: amorphous to ellipsoidal mass of large granules, not exactly median, but closer to one side of the sporocyst (line drawing); SZ: elongate, slightly pointed at one end, slightly rounded at the other, and slightly longer than sporocyst (line drawing). Distinctive features of sporocysts: the sporocysts look similar to an oocyst of Monocystis (line drawing).

Prevalence: Unknown.

Sporulation: Unknown.

Prepatent and patent periods: Unknown.

Site of infection: Intestinal mucosa.

Endogenous development: Not described (?). However, Phisalix (1933) described endogenous stages of an Eimeria sp. from Triton alpester (=Mesotriton alpestris) collected from the Jura and Alpes mountain range at 800 m and 2100 m elevation respectively, and around Paris. Those oocysts were 35 wide and sporocysts were 14 x 7, as were the sporozoites, suggesting that the species may be E. spherica. In the descriptions, meronts were 12–25 x 10.5–20 and contained 8–24 merozoites which were 8.4–21 x 3–3.1. Fully formed microgametocytes were ovoidal, measured 23 x 27, and contained at least 150 microgametes; microgametes were 6 x 3. Mature macrogametes were oval, 20 x 25, and took up the entire host cell.

Materials deposited: None.

Remarks: This species was first described by Schneider (1887) in a 1 page note and later redescribed in detail by Lavier (1936). It has not been reported since then.