Calosoma (Chrysostigma) simplex LeConte, 1878

Length 20-22 mm. C. simplex and C. affine, have the pronotum, narrower behind and the sculpture of elytra is almost smooth, the striae being indicated by superficial punctures only. C. simplex is distinguished by the less transverse pronotum, by its diminutive size, and by the absence of visible foveae on the primary intervals.
Breuning (1928a: 113) and Gidaspow (1959: 271) quote captures of C. simplex in various localities of California only. Burgess and Collins (1917: 93) cite it also from Arizona, Colorado, Texas, and from Mexico, to which Erwin (2007: 81) erroneously adds New Mexico but Bousquet (2012: 243) deems all these data incorrect and thinks that C. simplex is confined to California.
C. simplex was listed in the Hawaiian fauna, following acclimatization experiments carried out in the 1920s, but at the time the species was erroneously identified and confused with C. semilaeve to which the citation must therefore refer (Liebherr et al., 2023).

Examined specimens and literature’s data
United States. California: Madera co. Mojave desert (Breuning, 1928: 113), Merced co. (Pinoche Hill), San Benito co. (Panoche), San Bernardino co. (Victorville), Yolo co. (Davis) (Gidaspow, 1959: 272), Fresno County (SB), Los Angeles (AMNH), Los Angeles co. (www.inaturalist.org/observations/5618467), Kern co. (http://bugguide.net/), Riverside co. (UASM), Riverside co. (Palm Springs) (Gidaspow, 1959: 272), San Diego co. (Mission Trails Regional Park), (www.inaturalist.org).

Notes: Winged. It is found from lowlands to uplands up to 2100m altitude. Adults have been found in March-June, according to the data of the examined specimens,but should remain active up to August and in October-November (Erwin, 2007:81).

Calosoma (Chrysostigma) simplex ♀ LeConte, 1878 United States: California, Huron (Fresno County), May, 7, 07; from R. Hopping collection