A new coccidian from Acomys cahirinus Desmarest, 1819, from Evolution Canyon, Lower Nahal Oren, Mount Carmel, Israel.

In 1994, fresh fecal samples were collected and examined for coccidian parasites from 43 spiny mice (Acomys cahirinus) and from 60 wood mice (Apodemus mystacinus). The 2 genera of rodents inhabit an area in Lower Nahal Oren. Mount Carmel, Israel, known as Evolution Canyon, which consists of opposite-facing slopes that are geologically identical, but micro-climatically very different. Acomys cahirinus is found primarily on the warmer and drier south-facing slope (SFS), whereas A. mystacinus primarily inhabits the cooler and wetter north-facing slope (NFS). None of the samples from the A. mystacinus contained coccidia, but 6 of 43 (14%) A. cahirinus individuals were discharging eimerian oocysts that we describe herein as a new species. Five of the 6 positive samples were from the SFS. Sporulated oocysts are ovoidal to subspheroidal, 26.5 x 22.9 (21-29 x 19-26) microns, without a micropyle, but with an oocyst residuum of 1 to several large clear globules and a medium-sized refractile polar body; they contain lemon-shaped sporocysts, 10.4 x 8.1 (10 11 x 7-10) microns, with a sporocyst residuum and Stieda body, but no sub-/or parastieda body. Sporozoites lie side by side, completely filling oocysts; each contains a large posterior refractile body.