Eimeria tanabei Levine and Ivens, 1979
Synonym: Eimeria sp. 2 of Tanabe (1938).
Type host: Mogura robusta Nehring, 1891 (Syn. M. wogura coreana), Large Asian mole.
Other hosts: None reported to date.
Type locality: ASIA: Japan, Keijo, suburbs surrounding Keijo Imperial University.
Geographic distribution: ASIA: Japan.
Description of oocyst:
Oocyst shape: presumably ellipsoid;
number of walls: 1 (?);
wall thickness: <1.0 (?);
wall characteristics: thin, smooth;
L x W: 10-13 x 6-8;
L/W ratio: not given;
OR: absent (?);
PG: absent (?).
Distinctive features of oocyst: none.
Description of sporocysts and sporozoites:
Sporocyst shape: not given;
L x W: not given;
L/W ratio: not given;
SB: present (?);
SSB: absent (?);
PSB: absent (?);
SR characteristics: not given;
SP: not given.
Distinctive features of sporocyst: none.
Prevalence: 26/26 (100%).
Sporulation: Exogenous (?).
Prepatent and patent periods: Unknown.
Site of infection: Distal to the host cell nucleus in the villar epithelium of the intestine.
Ensogenous development: Usually a single organism was present in an epithelial cell, but sometimes 2-3 were present. A unique feature of this species is that a "crescent body is connected with every endogedous (sic) stage." This body stained with H & E, with iron-hematoxylin, was Feulgen positive. Tanabe (1938) believed it was not a deformed host cell nucleus.
Young meronts were small, ~1.8, and eventually gave rise to 16 lancet-shaped merozoites, without a residual body, that each measured 5-8 x 0.7-1.0. Merozoites had an oval nucleus, located in their posterior part, with a tiny, eccentric nucleolus, but no granules.
Young micro- and macrogamonts could not be distinguished from young meronts. Tanabe (1938) provided drawings of these developmental stages, but gave no measurements. He noted that microgametes "are the smallest of any of the species described." Macrogamonts had coarse granules that became larger and more numerous as they developed. The nucleus of young macrogamonts had a large, central nucleolus and, as development progressed, the nucleus enlarged to about half the size of the macrogamont. In general, the development of both micro- and macrogamonts proceeded in a manner "similar to those of E. scapani" (Tanabe, 1938).
Materials deposited: None.
Remarks: Tanabe (1938) described some of the endogenous stages (presumably) of this species. He was convinced that although it was similar to E. scapani, that it was, nonetheless, a different species, but he did not name it; unfortunatley, he did not describe the sporulated oocyst or provide a line drawing or a photomicrograph of one. Pellérdy (1974) did not mention this form in his classic mongraph on coccidia, so Levine and Ivens (1979) named this "new species" seen by Tanabe (1938) as E. tanabei "in order to bring it to the attention of other workers and to ensure that further research is done on it." Normally, this name would be placed into the species inquirendae because of the absence of a photo or line drawing of a sporulated oocyst, but Tanabe (1938) did provide minmal measurements of the oocyst and drawings and photomicrographs of both asexual and sexual engogenous stages. The real issue is whether or not the endogenous stages drawn by Tanabe (1938) can actually be attributed to this "species." Tanabe's work (1938) was based on tissue sections of 26 mole intestines, which he admits were all infected by at least 2 other coccidia, Caryospora caryolytica and E. scapani. All of the endogenous stages of C. caryolytica are reported to occur intranuclearly. It is not clear how he was able to distinguish between endogenous stages of 2 (presumed) Eimeria spp. that both had cytoplasmic endogenous development, in wild caught host animals, when the endogenous stages of both were not known when he did his study (i.e., how did he conclude which meront went with which species?). Finally, Levine and Ivens (1959) stated throughout their review that Tanabe's moles came from South Korea. However, even though Tanabe's paper is written in English, in several places (e..g., pp. 1, 48) he clearly states, "26 moles....which were captured alive in the suburbs of Keijo," which is in Japan.
References: Levine and Ivens (1979); Pellérdy (1974); Tanabe (1938).