Calosoma (Castrida) retusum (Fabricius, 1775)

Carabus retusum Fabricius, 1775: 237 (described from: littora Patagoniae; lectotype: Natural History Museum of Denmark, Copenhagen)
Calosoma laterale Kirby, 1818: 379 (type: Brasil; Natural History Museum, London)
Calosoma bonariense Dejean, 1831: 560 (type: Buenos Aires; Muséum National d'Histoire Naturelle, Paris)
Calosoma patagoniense Hope, 1838: 129 (type: Patagonia; British Museum of Natural History, London)
Callistriga retusum Motschulsky, 1865: 307
Calosoma (Callistriga) retusum Breuning, 1927: 198
Caminara (Callistriga) retusa Lapouge, 1932: 416
Caminara (Callistriga) lateralis Lapouge, 1932: 417
Castrida (s. str.) retusum Jeannel, 1940: 97
Calosoma retusum var dallasi Stévenin, 1944: 13
Calosoma (Castrida) Proseni Dallas, 1944: 5 (type: Salta Prov. Maimogasta; Museo Argentino de Ciencias Naturales, Buenos Aires)
Calosoma (Castrida) retusum Gidaspow, 1963: 303
Calosoma (Castrida) retusum Erwin, 1991: 102

Length 25-30 mm. retusum has rounded metatrochanter in both sexes, in some case slightly pointed in the male. The pronotum has a raised lateral border and rounded hind angles, extending backward, it is slightly wrinkled with few, sparse and shallow punctures. The elytral sculpture is characterized by striae underlined by large puncture and intervals weakly incised by transverse wrinkles.
The upper body is bronze green, sometime darker with bluish reflections, but often clearer and similar to alternans granulatum. When the characteristic of male's metatrochanter can not be used, retusum could be mistaken with it. The confusion can be avoided taking into account the typical sculpture of the elytra of retusum where all the intervals are of the same width. The female with the upper body bronze green could be also mistaken for fulgens as it has similar color and almost similar sculpture of the elytra. To avoid this, it suffices to consider the form of the lateral border and of the hind angles of the pronotum of retusum, and to remember that the intervals of its elytra are more convex and scaly.
It is common in southern Brazil, Uruguay, Argentina, but it is also present in Perù and Bolivia.

Examined specimens and literature’s data

Argentina. Rio Negro: Villa Regina (SB); Chaco (http://www.ebay /); Buenos Aires (SB); Buenos Aires (holotype of Calosoma bonariense MNHN) ; Northern districts of Patagonia (type of Calosoma patagoniense BMNH); Salta Prov. Maimogasta (type of Calosoma Proseni MACN)
Bolivia. Cochabamba: Sacaba 3300 m (SB); Andrés Ibáñez: Santa Cruz de la Sierra (http://www.ebay /)
Brazil. Rio de Janeiro; Santa Catarina: Nova Teutonia; Rio Grande do Sul, Pelotas (Gidaspow, 1963: 304)
Peru: Peru (SB); central peruvian desert (http://www.ebay /)
Uruguay. Canelones: Las Piedras (SB), Montevideo (Breuning, 1927: 199)

Notes: Winged, easily attracted to light at night (Jeannel, 1940: 97). Can be found in forest as well as in drier regions with sparse vegetation, in pastures and tilled fields. It has been noted in many occasions as a predator of caterpillars injurious to agriculture. Active individuals were found mostly in the wet season, from November to March.

Calosoma (Castrida) retusum
(Fabricius, 1775)
Argentina, Rio Negro: Villa Regina
Calosoma (Castrida) retusum
(Fabricius, 1775)
Bolivia, N.E. Sacaba 3.300m., 29.3.76, Coach lg.
Calosoma (Castrida) retusum
(Fabricius, 1775)
Buenos Aires
(holotype of Calosoma bonariense Dejean, 1831)
(Muséum National d'Histoire Naturelle, Paris)

Calosoma (Castrida) retusum
(Fabricius, 1775)
"Northern districts of Patagonia"
(type of Calosoma patagoniense Hope, 1838,
British Museum of Natural History, London)
(photo G. Narducci)