Key to the species of subgenus Castrida Motschulsky
1 elytral margin even, without trace of serration
(2)
--- elytral margin with evident serration
(8)
2 last segment of maxillary palps almost as long as, and hardly wider than, the preceding one, elytra light brown, head and pronotum black with green luster
rufipenne Dejean
--- last segment of maxillary palps shorter and distinctly wider than preceding one, upper body of one color only
(3)
3 pronotum with obtuse hind angles extending backward, color coppery red with green luster
trapezipenne Chaudoir
--- pronotum with small hind angles not extending backward
(4)
4 elytra smoot with scarce traces of sculpture, color brown matt without metallic luster
bridgesi Chaudoir
--- elytra with sculpture well recognaizable, or partially obliterated but still recognizable, color black or brown always mantaining traces of metallic luster
(endemic species of Galapagos islands) (5)
5 elytra with punctate striae and convex intervals, color black, with bluish or green luster, wings functional or reduced
(6)
--- elytra with partially obliterated sculpture, color brown or ligth brown, with faint metallic luster, utterly atrophied wings
(7)
--- head characterized by marked macrocephaly, wings reduced, reaching at most half of the elytron and not functional
leleuporum Basilewsky
7 wings very reduced, not reaching the half of elytron, upper body blackish-brown with very faint greenish reflection, (length 15-16 mm.)
galapageium Hope
--- wings completely atrophied, reduced to an almost invisible stump, body depigmented, smaller dimension (length 12-13 mm.)
linelli Mutchler
8 elytra with intervals of different width or heigth (sculpture of the elytra hétérodyname, sensu Jeannel) (the males have arcuated and pointed metatrochanter)
(9)
--- elytra with intervals all of the same width and heigth (sculpture of the elytra homodyname sensu Jeannel)
(10)
9 primary intervals larger than the others, secondary and tertiary ones of the same width, upperbody black or greenish black
sayi Dejean
--- primary intervals of the same width than the secondary ones, tertiary intervals markedly reduced in size and elevation, upperbody dark bronze or coppery with greenish luster (granulatum Party)
alternans (Fabricius)
10 pronotum with rounded, obtuse, hind angles extending backward
(11)
--- pronotum with very reduced, hardly recognaizable hind angles, not extending beyond the basal line
(12)
11 elytral sculpture flattened, foveae on the primary ones reduced, smaller than the width of the intervals themselves, intervals with fine transverse wrinkles, upper body dark brown without metallic luster
vagans Dejean
--- elytral sculpture raised, foveae on the primary ones, large as, or larger than, the intervals themselves
(13)
13 elytral sculpture with barely recognizable punctures on the striae and markedly scaly intervals, upperbody black, with bluish luster (the males can be easily identified by the hind tibiae arcuated as the middle ones)
peruviense Mandl
--- elytral sculpture with striae underlined by large puncture and intervals weakly incised by transverse wrinkles, upper body metallic green or bronze
retusum (Fabricius)
12 elytral sculpture with barely recognizable punctures on the striae and markedly scaly intervals, head and pronotum densely punctate on the entire surface, upper body coppery or bronze
argentinense Csiki
--- elytral sculpture with striae underlined by evident puncture
(14)
14 pronotum narrowed posteriorly and widest before the middle, elytral sculpture with all the intervals incised throughout their length by deep transverse wrinkles, including the primay ones, upper body dark metallic green or bronze (the males can be easily sorted out also because of the second segment of the anterior tarsi missing the depression on dorsal side, typical of the other species of Castrida)
abbreviatum Chaudoir
--- pronotum evenly rounded (more so in males), elytral sculpture with intervals very slightly convex. All the intervals are weakly incised by transverse wrinkles, except the chan-like elevation on the primary ones that are smooth. The upper body is reddish bronze (the males can be easily identified by the arcuated and pointed metatrochanter)
fulgens Chaudoir