Calosoma (Callistenia) subaeneum Chaudoir, 1869
C. subaeneum is characterized by a transverse pronotum with an almost smooth disk and roughness limited to its sides and to the rear part; the posterior lobes of pronotum are broadly rounded not projecting from the base. C. subaeneum can be distinguished from C. latipenne with which it has been sometimes confused, by its more elongate shape and by the elytral sculpture more detectable. On each elytron are clearly visible 15 intervals (triploid type); the striae are indicated by small punctures and on the intervals, although flat, it is possible to recognize shallow transverse wrinkles. The foveae on the primary intervals, in some case, can be quite large. The color of the upper body in the type is blackish but it can also be dark bronze with hints of blue.
Calosoma (Callistenia) subaeneum subaeneum Chaudoir, 1869
Calosoma subaeneum Chaudoir, 1869: 28 (described from California; holotype in Muséum National d'Histoire Naturelle, Paris)
Calosoma (Callisthenes) subaeneum Breuning, 1928: 81
Callisthenes (Callistenia) subaenea Lapouge, 1932: 378
Microcallisthenes (Callistenia) subaeneus Jeannel, 1940: 173
Callisthenes (Microcallisthenes) subaeneus Gidaspow, 1959: 304
Callisthenes (Callistenia) subaeneus Erwin, 2007: 82
Length 17-20 mm. Breuning (1928b: 81) indicates California as the only state where you can find the various populations of C. subaeneum . Jeannel (1940: 173), that did not knew the species, reports the data of Breuning, suggesting its presence in the southwestern slopes of the Sierra Nevada. But Gidaspow (1959) and Erwin (2007) indicate a wider distribution from southwestern Canada (British Columbia) up to California, spreading across the States of Idaho and Washington.
Examined specimens and literature’s data
United States: California (type, MNHN), Fresno (Breuning 1928b: 82)
Notes: Brachypterous. According to Erwin (2007: 82), the typical population should inhabit lowlands at an altitude of around 100m. Adults can be found in February-March.
Californie, ex Musaeo Chaudoir (Typus)
(coll. Muséum National d'Histoire Naturelle, Paris)
(photo: Mackenzie Flight)
Calosoma (Callistenia) subaeneum dawsoni Dajoz, 1997
Callisthenes (Microcallisthenes) dawsoni Dajoz, 1997:70 (described from California, Mono county)
Callisthenes (Callistenia) dawsoni Erwin, 2007: 76
Length 15-16 mm. An alleged additional new species, Callisthenes (Microcallisthenes) dawsoni Dajoz, 1997, of which have been found less than twenty specimens, has been described by the author in comparison with C. moniliatum, to which it should be similar because of the elongated shape and the color of the upper body, brilliant bronze or dark bronze.
Actually, as can be judged from the original description, it seems more similar to C. subaeneum because of the elongated body shape and the bronze color of the upper body. The more so because, as it happens in C. subaeneum, the elytral sculpture is characterized by striae identified by shallow punctures and by flat intervals, of which the primary ones are with large, metallic blue foveae.
The penis has an apex elongated and the ligula is thin with a bent end, as happens in many species of the subgenus.
In conclusions, in the absence of additional findings, it seems more probable that C. dawsoni is an ecologically well isolated population of C. subaeneum with some little morphological differences as more pronounced color and slightly smaller size.
Examined specimens and literature’s data
United States: California: Mono County, Big Alkali Lake, (road between Mammoth Lake and Benton), 2100 m. (Dajoz, 1997: 70)
Notes: The typical series comes from the Sierra Nevada in California (Mono County). More precisely, the specimens were collected in special ecological conditions, on the shore of Big Alkali Lake, near the road between Mammoth Lake and Benton, at 2100m altitude in August. We do not know other findings..
Dajoz Roger (1997), "Description et biologie d’un
Callisthenes nouveau de la Sierra Nevada
de Californie (Coleoptera: Carabidae)",
Nov. Revue Ent. (N. S.), T. 14, Fasc. 1: 70