Calosoma (Castrida) retusum (Fabricius, 1775)

Length 25-30 mm. C. 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 punctures and intervals weakly incised by transverse wrinkles.
The upper body is bronze green, sometime darker with bluish reflections, but often clearer and similar to the bronze green specimens (the so called granulatum ) of C. alternans. 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.
C. retusum is known and relatively common in Brazil, Uruguay and Argentina, there are also isolated findings in Paraguay, Chile, Peru and Bolivia, so possibly it is widespread throughout the centre-southern part of South America.

Examined specimens and literature’s data
Argentina. Buenos Aires: Buenos Aires (holotype of Calosoma bonariense MNHN) (SB), González Moreno (www.inaturalist.org), Rivadavia, Lomas de Zamora, Lobería, Mar del Tuyú, Saavedra (www.inaturalist.org), Monte Hermoso (www.ecoregistros.org/), Zelaya, Olivos, Tandil, La Plata (Gidaspow, 1963: 304), Balcarce, Miramar (www.gbif.org/); Chaco (http://www.ebay /); Cordoba: (Breuning, 1927: 199), Capilla del Monte (Gidaspow, 1963: 304), San Francisco (www.gbif.org/); Corrientes: Yapeyú (www.inaturalist.org); Entre Rios: Paranà (Gidaspow, 1963: 304); Jujuy: Yuto (Gidaspow, 1963: 304); Mendoza San Rafael (Gidaspow, 1963: 304), El Chacay, Anchoris (www.gbif.org/); Misiones (Breuning, 1928: 96); Riosario (Gidaspow, 1963: 304); Patagonia (type of Calosoma patagoniense BMNH), Northern districts of Patagonia: Cape Gregory (Curtis,1839: 181); Rio Negro: Villa Regina (SB), Cipolletti, Lamarque; Salta: Maimogasta (type of Calosoma Proseni MACN), General Roca (www.gbif.org/), La Merced (www.inaturalist.org); San Luis: Villa de Merlo (www.ecoregistros.org/ ), El Peje (Gidaspow, 1963: 304); Santa Fé : Hersilia (Gidaspow, 1963: 304), villa de Santa Fe, Villa Guillermina (www.gbif.org/); Santiago del Estero (Breuning, 1927: 199); Tucuman (Gidaspow, 1963: 304), villa de Tucumán (www.gbif.org/); rio Colorado (Breuning, 1927: 199), rio Salado, Rio Parana (Gidaspow, 1963: 304)
Bolivia (Breuning, 1928: 96): La Paz: Mocomoco (www.inaturalist.org).
Brazil. Ceará: Coreaú (www.inaturalist.org); Espírito Santo: Itapemirim (www.gbif.org/); Rio Grande do Sul: Pelotas (Gidaspow, 1963: 304), Manoel Viana (www.inaturalist.org); Rio de Janeiro: (Gidaspow, 1963: 304), Itatiaia (www.gbif.org/); Santa Catarina: Nova Teutonia (Gidaspow, 1963: 304); São Paulo Saude (www.gbif.org/), Garça (www.inaturalist.org).
Cile. Santiago: Renca (IADIZA-CEI reported in www.gbif.org/)
Paraguay. Guairá: Villarrica (www.gbif.org/)
Peru. Lima (YPM, discover.odai.yale.edu/); central peruvian desert (http://www.ebay /)
Uruguay. Canelones: Las Piedras (SB); Maldonato (sub laterale, Curtis,1839: 181); Montevideo (Breuning, 1927: 199); Colonia: El Semillero (www.inaturalist.org)

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)