Calosoma (Castrida) alternans (Fabricius, 1792)

Calosoma (Castrida) alternans alternans (Fabricius, 1792)

Carabus alternans Fabricius, 1792: 146 (type: "Americae insulis"; Zoologischen Museums der Universität Kopenhagen)
Calosoma laterale Dejean, 1826: 199 (preoccupied by Calosoma laterale Kirby, 1818) (type: Brésil; Muséum National d'Histoire Naturelle, Paris)
Calosoma granulatum Perty, 1830: 9 (type: Brésil)
Calosoma brullei Blanchard, 1843: 42
Calamata coxalis Motschulsky, 1865: 307
Calamata rugata Motschulsky, 1865: 308
Calosoma (Callistriga) alternans Breuning, 1927: 192
Calosoma (Callistriga) granulatum Breuning, 1927: 195
Caminara (Callistriga) alternans Lapouge, 1932: 417
Castrida alternans Jeannel, 1940: 95
Castrida alternans ssp granulatum Jeannel, 1940: 96
Calosoma (Castrida) alternans Gidaspow, 1959: 241
Calosoma (Castrida) alternans granulatum Gidaspow, 1963: 300
Calosoma (Castrida) alternans Erwin, 2007: 86

Length 24-30 mm. C. alternans differs from C. sayi, which is the only other species of Castrida with elytral, sculpture of heterodynamic type, because, while the primary intervals are of the same width than the secondary ones, the tertiary intervals are markedly reduced in size and elevation.
C. alternans occupies the Central America and the northern part of South America with dark brown populations superficially similar to C. sayi. The males of these populations, in general, have only one or two basal articles of the anterior tarsi with scarce hairy pads on the ventral side, on the apical part only.
Instead, the populations of central western part of South America up to northern Argentina have a brightly metallic upper side of the body, with the pronotum slightly more transverse. Moreover, in these populations the males have three articles of the anterior tarsi with thick hairy pads, as it is the rule in the other species of Castrida.
These populations were regarded by Breuning (1927: 195) as pertaining to a distinct species, but were considered by Jeannel (1940: 96), and by later authors, rather as constituting a southern subspecies of C. alternans. However, considering the large areas of intergradation and the occasional mingling of individuals of one type or another inside the same population, more recent authors (Erwin, 1999: 20) prefer to consider the infraspecific subdivision unnecessary.
To summarize, in Central America, dominates a dark brown morphotype of C. alternans that, according to (Erwin, 1991: 22), has been found in the southern part of Panama and, more rarely, in Honduras, where C. sayi is also present. The same happens in the northern part of South America: Lesser Antilles (Dominica, Martinique, Trinidad), British Guiana, Colombia, Venezuela, Peru and northern Brazil. Starting from Brazil, we found populations where the bright metallic morphotype is more common. These populations spread in central and southern Brazil, Bolivia, Paraguay, Uruguay, Argentina.

Material examined:
Colombia: La Coruna
Venezuela: Araqua (Palo Negro)
Perù: Nazca (Ica 590m)
Brazil: Rio de Janeiro (Rio Bonito); Bahia (Villa Victoria); Santa Catarina (Florianopolis, Nova Teutonia); Mato Grosso (Uirapuru)
Paraguay: San Pedro (Nova Germania, Cororo); Caaguazu
Uruguay: Canelones (Las Piedras)
Argentina: Misiones (Panambi); Entre Rios (Pronunciamiento)

Notes: Winged. It is attracted to the light at night. Adults and larvae may be caught using pitfall traps.
It lives in a variety of habitat from evergreen forests to pastures and plantations. In some cases (Bolivia), it has been noted as a possible auxiliary to agriculture because of predation of caterpillars injurious to cotton plantations such as Alabama argillacea and Spodoptera frugiperda (Allen, 1977: 74).
Active individuals were captured mostly in the rainy season, from October to April.

Calosoma (Castrida) alternans
(Fabricius, 1775)
Perù, Ica prov., Nazca 590m., 9-11.3.1988, Czadek lg.
Calosoma (Castrida) alternans
(Fabricius, 1775)
Argentina, Misiones, Panambi, XII.57, Walz lg.
Calosoma (Castrida) alternans granulatum
Perty, 1830
Paraguay, San Pedro prov., 6km NW Nova Germania, 8-11.II.2008, Halada lg.
Calosoma (Castrida) alternans granulatum
Perty, 1830
Brazil, Bahia, Villa Victoria, Ch Pujol 1890
Calosoma (Castrida) alternans granulatum
Perty, 1830
Brésil (holotype of Calosoma laterale Dejean, 1826)
(coll. Muséum National d'Histoire Naturelle, Paris)