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 ♂ designated by Deuve (1978: 250) by monotypy in Muséum National d'Histoire Naturelle, Paris [examined]
Calosoma (Callisthenes) subaeneum Breuning, 1928: 81
Callisthenes (Callistenia) subaenea Lapouge, 1931: 378
Microcallisthenes (Callistenia) subaeneus Jeannel, 1940: 173
Callisthenes (Microcallisthenes) subaeneus Gidaspow, 1959: 304
Callisthenes (Callistenia) subaeneus Erwin, 2007: 82

Length 17-20 mm. C. subaeneum has been described from California to which Burgess & Collins (1917: 114) add Idaho and Washington; but later Breuning (1928b: 81) and Jeannel (1940: 173) indicate California as the only state where C. subaeneum does exist.
Gidaspow (1959: 305), as later confirmed by Erwin (2007: 82), took up again the indications of Burgess & Collins and as a matter of fact proposed a wider distribution from southwestern Canada (British Columbia) up to California, spreading across the States of Idaho and Washington. However, the indication of British Colombia remains very uncertain because it originates from a single vague quote from Venables (1913: 268) taken up by Hatch (1953: 53) but questioned by Bosquet (2012: 251) who reports an opinion of Lindroth (1961 : 53)

Examined specimens and literature’s data
United States. California (type, MNHN), Fresno (Breuning 1928b: 82); Idaho (Burgess & Collins 1917: 114); Washington (Burgess & Collins 1917: 114)

Notes: Brachypterous. According to Erwin (2007: 82), the typical population should inhabit lowlands at an altitude of around 100m. Adults were found in November and February-March.

Calosoma (Callistenia) subaeneum
Chaudoir, 1869
Californie, ex Musaeo Chaudoir (Typus)
(coll. Muséum National d'Histoire Naturelle, Paris)
Calosoma (Callistenia) subaeneum
Chaudoir, 1869
(photo: Mackenzie Flight)

Calosoma (Callistenia) subaeneum dawsoni Dajoz, 1997

Callisthenes (Microcallisthenes) dawsoni Dajoz, 1997:70 (type locality: California, Mono county) type material: 19 specimens, no repository given
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..
The taxon was named after Daniel R. Dawson, at the time director of Sierra Nevada Aquatic Research Laboratory, who facilitated the researches and the discovery of the new Calosoma.

Calosoma (Callistenia) dawsoni
Dajoz, 1997
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

last review April 21 2019