Type host: Molossus ater Goeffroy, 1805, Velvety free-tailed bat.

Other hosts: None reported to date.

Type locality: SOUTH AMERICA: Brazil, Amazonas, suburbs of Manaus.

Geographic distribution: SOUTH AMERICA: Brazil.

Description of oocyst: Oocyst shape: sometimes subspheroidal, but mostly broadly ellipsoidal; number of walls: 3; wall thickness: not given; wall characteristics: outer 2 are closely contiguous, yellowish-brown, prominently striated in optical cross-section; inner, thin, smooth and colorless; L x W: 23.4 x 17.5 (18-30 x 15-22.5); L/W ratio: 1.3 (1.0-1.6); M: absent; OR: absent; PG: 1-2, conspicuous, ellipsoidal, ~1.9 long. Distinctive features of oocyst: 3-layered wall giving a striated appearance.

Description of sporocysts and sporozoites: Sporocyst shape: broadly ellipsoidal to ovoidal; L x W: 10.3 x 7.5 (10-12.5 x 7.5); L/W ratio: 1.4 (1.3-1.7); SB: present as a small nipple-like structure; SSB: absent; PSB: absent; SR: present; SR characteristics: 4-12 relatively large spherules between SP; SP: oriented head-to-tail, longer than and filling most of sporocyst so that they recurve on themselves; 1 RB at rounded end of SP. Distinctive features of sporocyst: very thin wall and SP that are longer than sporocyst.

Prevalence: 17/38 (45%).

Sporulation: Exogenous. Sporulation time is unknown, but it was noted that sometwimes >70% of the oocysts in a given fecal sample failed to sporulate when stored in 2.5% aqueous (w/v) potassium dichromate solution left at 23-24 C.

Prepatent and patent periods: Unknown.

Site of infection: Epithelial cells of the ileum with all stages positioned between the brush border and the host cell nucleus, which becomes distended and later destroyed by the growing stages.

Endogenous stages: Meronts (n=6) were 12.3 x 9.3 (11-14 x 8-10) and produced 8-12 merozoites, ~6 x 1. Microgametocytes measured 15.8 x 11.8 (15.5-17 x 11-12), had a bulky RB, 10 x 8, and shed >50 microgametes, 3 x 0.5. Young macrogametocytes are first spheroidal and later become ellipsoidal, 18 x 14; glycoprotein granules then become conspicuous and some are 2 in diameter. The oocyst wall is fully developed before the oocysts are shed into the gut lumen.

Pathology: No outward signs of disease, but histological sections showed damage of the epithelium presumed to be caused by the parasite and endogenous stages were commonly seen together with sloughed epithelial cell debris in the gut lumen.

Materials deposited: None.

Remarks: This is the only species described from Molossus. Its sporulated oocysts most closely resemble those of E. eumopos (from Eumops trumbuli another molossid) and those of E. macyi (from Pipistrellus subflavus, Vespertilionidae), both of which have a roughish, striated outer oocyst wall. The oocysts of E. eumopos are larger than those of E. molossi (35 x 28 vs 23 x 17) and the former has an oocyst wall with only 2 layers. In addition, there are significant size and number differences in the endogenous developmental stages between the two species. The oocysts of E. macyi are smaller, and more spheroidal in shape than those of E. molossi (19 x 17.6 vs 23 x 17) and have sporocysts with a distinct SSB, which those of E. molossi lack. Finally, there are no cross-transmission studies done with the coccidia of bat species, so we know nothing about host specificity within the Chiroptera. In at least one other mammalian lineage (e.g., Sciuridae), some Eimeria species apparently are successfully shared between host species in different genera (Wilber et al. 1998); however, in other mammals (e.g., Muridae), Eimeria species usually can be transferred between species within the same genus, but generally not between hosts in different genera (Hnida et al. 1999). Thus, it is not possible to say with certainty whether eimerians with similarly structured oocysts can exist in more than one host genus.

References: Hnida et al. (1999); Lainson and Naiff (1998); Wilber et al. (1998).