Calosoma (Camedula) sponsa Casey, 1897

Length 16-19 mm. As happen with C. glabratum and C.peregrinator C. sponsa is characterized by the presence of setae on the metatrochanters.
If we do not consider this character, C. sponsa can be confused with C. parvicolle which has almost the same dimensions, with a slightly transverse, a little more angular pronotum, equally elongated elytra and a similar slender shape of the copulatory organ of the male, with a decidedly thin and elongated apex.
Breuning (1928a: 103) taking into account the character of the presence of setae on the metatrochanters, considered C. sponsa conspecific with C. glabratum and C. peregrinator, and believed C. eremicolaits junior synonym.
Jeannel (1940) instead thought that the C. sponsa of Casey (1897) was a reduced size form of C. peregrinator, while C. eremicola was a valid species to which could apply the diagnosis of Calosoma (Carabosoma) glabratum ssp sponsum of Breuning.
Gidaspow (1959) who examined the type of C. sponsa, considered it a valid species, distinct from C. peregrinator. Also C. eremicola, according to Gidaspow should be a valid species, from which C. sponsa would be distinct by the more slender body shape, and by apex of male's copulatory organ that should be slightly more curved.
The differences between C. sponsa and C. eremicola are very slight, and, some of them, such as the possibility of some specimens having a more transverse pronotum and a more squat body shape are possibly due to the individual variability. For this reason, going back to the opinion of Breuning, it seems preferable to consider the two taxa as a single species, to which, obviously, the name sponsa should be applied.
The type of C. sponsa comes from Utah, the type of C. parviceps from Arizona, the type of C. eremicola from S. Clemente island in California, and the one of C. peregrinator incerta from Baja California in Mexico.
C. sponsa, as we consider it here, is undoubtedly a species linked to the dune and desert environment. It is mainly located in the Mojave desert and in the Colorado desert (southern California, Baixa California and western Nevada) but it is also present in parts of the Great Basin desert (northern Nevada, Utah, a station in Colorado), of the Sonora desert (southern Arizona) and in some bordering areas in the Chihuahua desert (New Mexico).

Examined specimens and literature’s data
Mexico. Baixa California: Ensenada (sub eremicola, Gidaspow, 1959: 259)
United States. Arizona (Breuning, 1928a: 107): Maricopa County, South Mountain Regional Park (http://madrean.org/); California: Lowell, San Diego County (sub eremicola, AMNH), San Bernardino County (AMNH), Mono County (AMNH), Indipendence, Big Pine (Gidaspow, 1959: 260), Inyo Co., Santa Catalina Island (sub eremicola, Gidaspow, 1959: 260), Santa Barbara island (www.inaturalist.org), San Clemente Island (Breuning, 1928a: 107), North San Clemente island (www.inaturalist.org), Coronado, Imperial County, Algodones Dunes (/www.inaturalist.org); Colorado: Montezuma Co. (sub eremicola, Bousquet, 2012: 235); New Mexico: Faywood (sub eremicola, Gidaspow, 1959: 259), Bernalillo County, Albuquerque (http://madrean.org/); Nevada: Esmeralda Co., Washoe co. (sub parviceps, La Rivers, 1946: 136); Churchill Co., Mineral Co, Pilot Mountains (Gidaspow, 1959: 260); Utah: Millard Co. (Bousquet, 2012: 236), Grand county, Emery county, Tooele County (http://bugguide.net/).

. Notes: Winged. It has been found from 100 to 1200m of altitude. Adults seem to be active in March - August (Larochelle & Larivière, 2003: 183)
Breuning (1927b: 103), corrected the name of the species in sponsum. In some case subsequent authors accepted this correction, but it is incorrect because the noun "sponsa" do not need to agree in gender with the name of genus Calosoma (International Code of Zoological Nomenclature, art. 31.2.1) and therefore remains valid the name given by Casey.

Calosoma (Camedula) sponsa ♂ Casey, 1897 California, E. Dongé (sub. eremicola Fall 1910) (coll. Muséum National d'Histoire Naturelle, Paris)

Calosoma (Camedula) sponsa ♀ Casey, 1897 California, Mono county, White Mts., Crooked creek, 20.VI.1961DH Miller (coll. American Museum of Natural History, New York)

Calosoma (Camedula) sponsa ♀ Casey, 1897 California, San Bernardino county, Kane Spring near Newberry, 27.III.1964, E. Ball jr. lgt. (coll. American Museum of Natural History, New York)