Xystosomus gruti, Bates, 1871

Erwin, Terry L., 1973, Studies of the subtribe Tachyina (Coleoptera: Carabidae: Bembidiini), Part I: A revision of the Neotropical genus Xystosomus Schaum, Smithsonian Contributions to Zoology 140, pp. 1-39 : 7

The gruti group

The members of the gruti group are characterized by similarities of the male genitalia, especially by the presence of a "brush sclerite" on the internal sac of the median lobe. The same kind of

sclerite is also found well developed in all members of the genera Bembidion (except where secondarily reduced, for example in the vile group) and Asaphidion . Externally, the members of the gruti group are characterized by the following combination of characteristics: large eyes; large and strongly developed carinae posterolaterally on the pronotum; transverse pronotum wider than head across eyes; broadly explanate sides of the pronotum and elytra; presence of two pairs of lateral setigerous pores on the pronotum (except Xystosomus negrei ); sulcate prosternal process; fully developed flight wings; and relatively large body size (some of the largest members of Tachyina ).

Besides the combination above, many species of this group have members with iridescent or metallic green dorsal surfaces (the only Tachyina with metallic coloration) and deeply engraved, punctate elytral striae.

Presently representing this group are 16 species with a combined range (Figure 69) extending from southern Mexico to southern Brazil.