Oocysts of Caryospora ernsti n. sp. (Apicomplexa: Eimeriorina), from the feces of the green lizard, Anolis carolinensis, are described. Oocysts are spherical, 12.5 (11.0-14.5) Atm, with a single-layered wall about 1.0 gtm thick. Micropyle and oocyst residuum are absent; a polar granule is present. Sporocysts are ovoid, 10.7 x 8.3 (10.012.5 x 7.5-9.0) Am, and possess Stieda and substieda bodies. A sporocyst residuum is present, 5.6 x 3.8 (3.6-6.3 x 2.7-5.4), and consists of numerous granules 0.3-1.5 um in diameter. Sporozoites are elongate, 9.7 x 2.0 (8.0-11.0 x 2.0-2.2) ,im, lying lengthwise and parallel within the sporocyst. Each sporozoite contains a spherical anterior and spherical or ovoid posterior refractile body. The genus Caryospora consists of coccidia which are characterized by monosporocystic, octozoic oocysts. Recent studies have shown that several species of Caryospora are heteroxenous (Cawthorn & Stockdale, 1982; Stockdale & Cawthorn, 1981; Upton et al., 1983a,b; Wacha & Christiansen, 1982), with predatory reptiles or birds serving as primary hosts and rodents serving as secondary hosts. During a routine survey of parasites of reptiles in the Atlanta Zoo in Georgia, several green lizards, Anolis carolinensis, were found to be infected with a new species of Caryospora. In this paper, we describe the oocyst of the new species and compare it morphologically with similar species of Caryospora infecting reptiles. MATERIALS AND METHODS In October 1982, 11 living adult specimens of Anolis carolinensis Voigt (green lizards) were shipped to our laboratory by the Atlanta Zoo. Eight of the lizards were housed in two groups of four in 38-liter glass aquaria containing a bed of peat moss; the remaining three were housed individually in 3.8-liter plastic aquaria. They were given water and European house crickets, Acheta domesticus (L.) ad libitum. Fecal casts collected from lizards housed individually and examined with Nomarski interference contrast (NIC) microscopy revealed the presence of unsporulated coccidian oocysts in two of the lizards. Feces were placed in Petri dishes in a thin layer of 2.5% (w/v) potassium dichromate (K2Cr2O7) at 2528?C and re-examined 24 h later. A single infected lizard was killed on day 3 and another on day 5 after arrival. Mucosal scrapings from the intestine of both lizards were examined by NIC microscopy for developmental stages of the parasite. The remaining lizards were killed and examined similarly 15 days Department of Herpetology, Atlanta Zoological Park, Atlanta, Georgia 30315, U.S.A. TRANS. AM. MICROSC. Soc., 103(3): 245-248. 1984. ? Copyright, 1984, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.116 on Sun, 18 Sep 2016 06:37:09 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC.