Type host: Antrozous pallidus Le Conte, 1854, Pallid bat.

Other hosts: None reported to date.

Type locality: NORTH AMERICA: USA, New Mexico, San Juan Co., Upper Pump Canyon, near Twin Tanks, 36º 51' 80" N, 107º 47' 40" W.

Geographic distribution: NORTH AMERICA: USA, New Mexico, Mexico: Baja California Sur.

Description of oocyst: Oocyst shape: subspheroidal; number of walls: 2; wall thickness: 1.2-1.5; wall characteristics: outer, strongly sculptured, ~3/4 of total thickness; inner, smooth; L x W: 24.8 x 21.6 (22-27 x 19-24); L/W ratio: 1.15 (1.0-1.3); M: absent; OR: present; OR characteristics: usually a large lipid-like sphere, ~8, but sometimes 2-3 smaller spheres; PG: 1, highly refractile, ~3. Distinctive features of oocyst: sculptured nature of oocyst wall plus lipid-like OR.

Description of sporocysts and sporozoites: Sporocyst shape: ovoidal; L x W: 11.5 x 7.8 (9-13 x 7-10); L/W ratio: 1.5 (1.2-1.7); SB: present, prominent, ~3 wide; SSB: absent; PSB: absent; SR: present; SR characteristics: many large granules sometimes obscuring SP; SP: with a spheroid RB at rounded end. Distinctive features of sporocyst: prominent SB and SR that obscures SP.

Prevalence: 2/17% (12%).

Sporulation: Presumably exogenous. Oocysts sporulated in 2% aqueous (w/v) potassium dichromate solution in the field.

Prepatent and patent periods: Unknown.

Site of infection: Unknown. Oocysts recovered from feces.

Materials deposited: Type host recorded as Antrozous pallidus NK 41192, 10 July 1996 (animal released after identification). Photosyntypes of sporulated oocysts in the USNPC No. 88094.

Remarks: These sporulated oocysts were reported in 12/85 (14%) pallid bats from 2 of 5 collection localities in New Mexico and Mexico (Scott and Duszynski, 1997); it wasn't named then because of the similarity of these oocysts to those of E. arizonensis, a known parasite of rodents. The authors suggested that naming this form be delayed until cross-section and/or molecular studies could be completed to demonstrate the bat and rodent Eimeria species as distinct from each other. However, the regularity and the high prevalence in some bat populations strongly suggests this is not a spurious infection; it now has been found in 14/36 (39%) pallid bats from 2 counties in New Mexico (6/11, 55% in Eddy Co.; 2/17, 12% in San Juan Co.) and in Baja California Sur, Mexico (6/8, 75%), but not in 66 pallid bats from Bernalillo, Sandoval, or Lincoln counties in New Mexico (Duszynski et al., 1999; Scott and Duszynski, 1997). Recently, Zhao et al. (2001) demonstrated conclusively that partial plastid 23S and nuclear 19S rDNA genes that were amplified from both E. antrozoi and E. arizonensis clearly separated them, confirming that E. antrozoi is a valid species. Interestingly, additional phylogenies based on a combined data set of both plastid and nuclear partial sequences grouped 2 bat (E. antrozoi, E. rioarribaensis) and 3 morphologically similar rodent Eimeria species (E. arizonensis, E. albigulae, E. onychomysis) into 2 separate clades with high bootstrap support (100% and 85%, respectively). This could suggest that some Eimeria species from bats may be derived from rodent Eimeria species and may have arisen as a result of lateral host transfer between rodent and bat hosts.

Structurally, E. antrozoi is most similar to E. tomopea and to E. redukeri. It differs from the former by having smaller oocysts (25 x 22 vs 31 x 25) and sporocysts (11.5 x 8 vs 14 x 9) and in having a large, prominent SB vs one that is not easily seen unless the sporocysts are freed from the oocyst. It differs from E. redukeri by having a thicker oocyst wall (1.5 vs 1.0), larger oocysts (25 x 22 vs 20 x 18), a wide, conspicuous SB, and by having a prominent SR of many large granules vs one with only 1-3 spheroids.

References: Duszynski et al. (1988; 1999); Scott and Duszynski (1997); Zhao et al. (2001).