Calosoma (Castrida) bridgesi Chaudoir, 1869

Length 18-20 mm. As C. trapezipenne and as all the endemic species of Galapagos islands, C. bridgesi is characterized by the elytral margin even, without trace of serration.
C. bridgesi is a brachypterous species living at high altitude on the Andes in Bolivia, and, accordigly to dubious data, supposely penetrating in the neighboring states of Argentina and Chile. It is rather slender, black with reddish brown elytra, the metatrochanter has one seta, The metepisternum has few large punctures, the elytra are smooth with faint traces of striae and a deep depression in their middle. The basal seta of the pronotum is, in most cases but not always, present. The mesotibiae are strongly arcuated in both sexes.
Some of these unusual characteristics led Breuning (1927) to create for bridgesi a new subgenus, Neocalosoma. This was accepted by Jeannel but only as subgenus of the genus Castrida. Later Gidaspov (1963) has considered Neocalosoma as separate subgenus more related to Callitropa (Blaptosoma), giving priority to the affinity with the latter that Jeannel already had noted but considered as a phenomenon of evolutionary convergence. The attribution of bridgesi to Castrida by Jeannel seems strongly justified taking in the mind the numerous characteristics that bridgesi has in common with the other species of Castrida, as for exemple the important presence of an oval apical tuft of red hair on the internal side of the male's mesotibiae. This apical tuft has the oval shape that is typical of Castrida and it does not exists in this shape in the other phyletic lines, Callisthenes and Callitropa. A fortiori, the morphological effects of adaptation to habitat specific conditions are not automatically sufficient to justify artificial separations above the species level. This has also been the opinion of Basilewsky (1968) when dealing with the Castrida of the Galápagos Islands, for which, for instance, had been created another superflous subgenus: Microcalosoma.
On the basis of currently available data, bridgesi seems to be localized in a restricted area of high altitude of the Bolivian Andes. In fact all the latest documented catches are restricted to the region of Cochabamba in Bolivia while the provenance of one of the two specimens examined by Chaudoir from Tucuman in Argentina, remains dubious and the repeated citations of Chile, all of them based on the identification of two specimens seen by Roeschke (1900b: 71) at the British Museum , and on the label of another specimen also of Roeschke preserved at the Muséum National d'Histoire Naturelle in Paris, have never been confirmed.

Examined specimens
Bolivia. Cochabamba: Aguirre (SB), Tiraque (SB), Siberia (SB), Waquanqui (EM), Ayapampa 3900m. (www.inaturalist.org)

Notes: Brachypterous, lives in the high Andean desert up to 3500m. On the basis of the material examined, the active adults were captured in the months of January and February that, in the region of Cochabamba, are the ones with more precipitation, but according to Erwin (2007: 80) some specimens were found also in October.
The name of this species intends to honour Thomas Bridges (1807 – 1865) British naturalist and traveller in Central and South America.

Calosoma (Castrida) bridgesi ♂ Chaudoir, 1869 Tucuman (holotype) (coll. Muséum National d'Histoire Naturelle, Paris)

Calosoma (Castrida) bridgesi ♂ Chaudoir, 1869 Bolivia, Cochabamba, Aguirre 3.200 m., 20.I.51

Calosoma (Castrida) bridgesi ♀ Chaudoir, 1869 Bolivia, Cochabamba, Siberia, 3.000, I.75