Calosoma (Carabomimus) politum Chaudoir, 1869

Length 13-18 mm. Jeannel (1940) thought C. politum, C. diminutum and C. C. morelianum being very close species since they have the same just arched pronotum sides, relatively short and rounded elytra, and are all characterized by a rounded apex of aedeagus. C. politum should differ from C. diminutum in generally larger size, longer elytra, without visible punctuation, pronotum not narrowed at base, and males with apex of aedeagus shorter and slightly inflected.
The distinction, already excluded by Roeschke (1900: 63), has been found to be problematic also by Gidaspow (1959: 293), which studied long series of specimens from the type localities and felt that the differences in the aedeagus shape of the two taxa, that Jeannel had indicated, were very slight. Subsequently Lassalle & van den Berghe (2011b: 296) denied any significant differences and affirmed that C. diminutum at most might be a subspecies of C. politum. Moreover, the same authors, having studied the type of Blaptosoma laevigatum var. nitidum Géhin, 1885, have recognized its identity with C. diminutum (=C. politum) and stated the unreliability of the locality indicated by Géhin.
Jeannel (1940:227) reported Toluca as the only known locality of C. politum and lists only Salazar, Mexico, for C. diminutum. Gidaspow (1959:293) confirmed Salazar for C. diminutum and indicated additional localities for C. politum, such as the slopes of Nevada de Toluca. Salazar is a locality of the State of Mexico and of the municipality of Lerma, on the way from Mexico City to Toluca. Here, we have found C. politum quite in numbers, while the range of C. morelianum starts slightly farther to the south.
To conclude, considering the contiguity of habitats, the minor differences in external shape and the existence of numerous transitional forms, we think that any distinction between C. politum, and C. diminutum is superfluous.

Examined specimens
Mexico. Mexico D F: Salazar 3050m (holotype of diminutum, MNHN) (AVT, EM), 10km West of Ciudad de Mexico 3000m (EM, SB); Mexico: Mexicalcingo (MCZR), Toluca (lectotype of politum MNHN), between Toluca and Nevado de Toluca 3200m (EM, SB), NW Agua Bendita (UASM), Cañada de Alferes 2500m (GP).

Notes: Brachypterous. C. politum has been found on tilled field, pastures and disturbed areas, in June-July and September. Specimens have been collected either under stones in pastures and grass or wandering during the warmest hours of the day. In this period, in July, several couples actively copulating have been observed. Therefore, probably, the phases of diurnal activity are also connected to mating behavior, as already noted by Vigna Taglianti & Bruschi (1986) in various species of carabomorphous Calosoma from tropical high mountains..
The descriptions of the third and second-instar larvae, are found in Vigna Taglianti & al., (2021: 92-93).

Calosoma (Carabomimus) politum ♂ Bates, 1891 Mexico: 10 km West Ciudad de Mexico, Puerto La Guardia, m 3000, 9.VII.1987, S. Bruschi leg.

Calosoma (Carabomimus) politum ♀ Bates, 1891 Mexico: 10 km West Ciudad de Mexico, Puerto La Guardia, m 3000, 9.VII.1987, S. Bruschi leg.

Calosoma (Carabomimus) politum ♂ Bates, 1891 Mexico: between Toluca and Nevado de Toluca, La Puerta, m 3200, 9.VII.1987, S. Bruschi leg.

Calosoma (Carabomimus) politum ♀ Bates, 1891 Mexico: 10 km West Ciudad de Mexico, Puerto La Guardia, m 3000, 9.VII.1987, S. Bruschi leg.

Calosoma (Carabomimus) politum ♂ Chaudoir, 1869 Mexico: cold region, (H. W. Bates, Biol. Cent. Amer.)