Eimeria os Crouch & Becker, 1931.
Type host: Marmota bobac
Other hosts: M. baibacina; M.
caudata; M. menzbieri; M. monax; M. sibirica.
Other names: Eimeria callospermophili; E.
giganteos; E. monacis.
Type locality: North America: USA, Iowa, Near
Other localities: Asia: Buriatia;
Description of oocyst: Oocyst shape: ovoid; wall
thickness: not given; layers: 1 (in
drawing); outer layer colour: clear to pale yellow; outer layer texture: smooth;
micropyle: present; micropyle width: not given; MC: absent; OR: absent; PG: absent;
size: 20-26 x 18-22; L/W ratio: not given. Distinctive features of the oocyst:
o÷cyst "endomembrane" sometimes protrudes through the micropyle and looks like a
Description of sporocysts and sporozoites:
Sporocyst shape: ellipsoid; size: 9-13 x
5-8; SB: present; SB L x W: not given; SB characteristics: small, dark (in drawing);
SSB: absent; PSB: absent; SR: present; SR characteristics: rounded or irregularly
biconvex, lying either to the side or between the SP; SR size: not given; SP: not
described. Distinctive features of sporocyst: none.
Remarks: Eimeria os was described from M.
monax by Crouch & Becker (1931). In 1941,
Machulsky described E. os from M. siberica, but the oocysts he
described lacked a
micropyle, a feature of E. os, and his description more closely matches E.
callospermophili. Svanbaev (1963) described a species as E. os, but
Levine & Ivens
(1965) thought it was E. monacis (see E. monacis remarks). In
1965, Dorney described and
photographed what he called E. os from M. monax, but the size was much
thus, we named Dorney's (1965) species, E. giganteos. Fleming et
(1979) and McQuistion & Wright (1984) reported E. os from M. monax,
followed the description in Dorney (1965); thus, it is likely they actually saw
References: Crouch & Becker (1931); Dorney (1965);
Fleming et al. (1979); Levine &
Ivens (1965); McQuistion & Wright (1984); Machulsky (1941, 1949); Nukerbaeva &
Abenov (1979); Svanbaev (1963); Svanbaev & Rachmatullina (1971).