Eimeria giganteos Wilber, Duszynski,
Upton, Seville & Corliss, 1998.
Type host:Cynomys ludovicianus
Synonyms: Eimeria cynomysis; E.
marmotae; E. os.
Other hosts: Cynomys ludovicianus;
bobak; M. monax.
Type locality: North America: USA, Colorado, near
Other localities: Asia: Kazakhstan; North America:
USA, Illinois, New York,
Description of oocyst: (from Vetterling, 1964
[primarily] and Dorney, 1965): Oocyst
shape: subspheroid to ovoid; wall thickness: 1.4; layers: 2; outer layer proportion
of total thickness: not given; outer layer colour: yellow-green; outer layer
texture: smooth; inner wall characteristics: not given; micropyle: present;
micropyle width: 5; MC: absent; OR: absent; PG: sometimes present; number of PGs:
0-1; PG shape: not given; PG L x W: 1-2.5; size: 32.5 x 28.4 (30-37 x 23-31); L/W
ratio: 1.2 (1.1-1.3). Distinctive features of oocyst: o÷cyst tapers toward
Description of sporocysts and sporozoites:
Sporocyst shape: lemon-shaped; size:
15-18 x 9-12; SB: present; SB L x W: not given; SB characteristics: prominent; SSB:
absent; PSB: absent; SR: present; SR characteristics: compact, composed of many
small granules (in drawing); SR size: not given; SP: vermiform. Distinctive features
of sporocyst: none.
Prevalence: 1 of 86 (1%).
Site of infection: Unknown. Oocysts collected from
Material deposited: Host symbiotype in the Colorado
State University Mammal
Collections # 10184 (Vetterling, 1964). There is a suitable drawing (Figure 1) in
Vetterling (1964) and a suitable photomicrograph (Figure 3) in Dorney
Etymology: The trivial name is derived from gigas-
(Gk, a giant) and os,
because Dorney (1965) originally named the form he saw as E. os.
Remarks: Vetterling (1964) found oocysts similar
in size to those of E. cynomysis
(30-37 x 25-31 [Vetterling, 1964] vs. 25-37 x 22-32 [Andrews, 1928]) and, thus,
emended the original description. However, Vetterling's (1964) oocysts were
smooth-walled and had a prominent SB while those of Andrews (1928) were rough-walled
with an inconspicuous SB. Thus, we renamed those of Vetterling (1964) to E.
giganteos. Dorney (1965) described and photographed what he called E. os
monax, but the sporulated oocysts he described were so much larger (34-37 x
than those of E. os (20-26 x 18-22) of Crouch & Becker (1931), that we
form Dorney saw was E. giganteos not E. os. The sporocysts measured
by Dorney (1965)
also were proportionally smaller than those of Crouch & Becker (1931) to further
support our decision to separate these species. Nukerbaeva & Abenov (1979) described
a species from M. bobak they called E. marmotae, (described by
but designated a species inquirenda by us because the description was based
unsporulated oocysts). The few descriptive characters (by Nukerbaeva and Abenov,
1979) are indistinguishable from the description by Vetterling (1964) for E.
cynomysis (now E. giganteos). Fleming et al. (1979) and McQuistion &
reported E. os from M. monax. However, they followed Dorney (1965);
therefore, it is
likely they all actually saw E. giganteos.
References: Dorney (1965); Fleming, et al. (1979);
McQuistion & Wright (1984);
Nukerbaeva & Abenov (1979); Vetterling (1964).