Synonyms: None.

Type host: Ambystoma opacum (Gravenhorst, 1807), marbled salamander.

Other hosts: None to date.

Type locality: USA: Louisiana: Webster Parish, Lake Bistineau State Park off State Highway 163 south of Doyline (32º 26.3' N, 93º 23.1' W).

Geographic distribution: USA: Arkansas, Louisiana, Texas..

Description of oocyst: Oocyst shape: subspheroidal to ellipsoidal; number of walls: 1; wall thickness: ~0.8-1.0; wall characteristics: thin; L x W: 36.6 x 33.1 (33-40 x 29-37); L/W ratio: 1.1 (1.1-1.2); M: absent; OR: present; OR characteristics: large, spherical, membrane-bound composed of humdreds of loosely packed homogeneous granules of various sizes surrounding a spherical vacuole 22.2 x 22.0 (20-26 x 19-26; PG: absent. Distinctive features of oocyst: OR with large vacuole surrounded by hundreds of loosely packed granules.

Description of sporocysts and sporozoite: Sporocyst shape: elongate-ellipsoidal with thin smooth single-layered wall ~0.5; L x W: 20.8 x 8.1 (19-22 x 7-9); L/W ratio: 2.6 (2-3); SB: present at one end as slight thickening of wall; SSB: absent; PSB: absent; SR: present; SR characteristics: spherical, consisting of a cluster of homogeneous granules often membrane-bound or broken into 2 pieces, 5.5 x 4.5 (4-8 x 3-7); SZ: arranged head to tail in sporocyst with anterior transverse striations, 19.7 x 3.4 (17-25 x 3-4), with large spherical to subspherical anterior RB near mid-point of SZ and spherical to subspherical posterior RB; distinct N located between RB. Distinctive features of sporocysts: anterior transverse striations of SZ.

Prevalence: 2/10 (20%) with 2/2 (100%) from Loouisiana, 0/5 from Arkansas, and 0/3 from Texas.

Sporulation: Exogenous. All oocysts were passed unsporulated or partially sporulated and became fully sporulated within 5 days at ~23ºC.

Prepatent and patent periods: Unknown.

Site of infection: Unknown. Oocysts recovered from rectal contents and feces.

Endogenous development: Unknown.

Materials deposited: Photosyntypes deposited as HWML 45798.

Remarks: Upton et al. (1993) described Eimeria opacum from A. opacum from Grant County, Arkansas. Oocysts of E. trauthi are much larger than those of E. opacum (36.6 x 33.1 vs. 29.4 x 28.0), have a single oocyst wall (bilayered in E. opacum), and possess an oocyst residuum and Stieda body, which are absent in E. opacum. No other salamander eimerian, including Eimeria ambystomae Saxe, 1955, originally reported by Saxe (1955) from tiger salamanders (Ambystoma tigrinum) from Iowa, and by Duszynski et al. (1972) from the same host species from Colorado and New Mexico, and by McAllister and Upton (1987) from smallmouth salamanders (Ambystoma texanum) from Texas, has been described with a combination of characters descriptive of the new species. In addition, this is the first time, to our knowledge, that a coccidian has been reported from any amphibian host in Louisiana.