Xystosomus laevis, Erwin, 1973

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 : 30

26. Xystosomus laevis , new species

FIGURES 22 d , 56 , 57 , 63 , 68 , 72

TYPE-LOCALITY.— Nova Teutonia , Santa Catarina, Brazil.

TYPE-SPECIMENS.—The holotype male and allotype are in MCZ. Six paratypes: MCZ, 3; USNM, 3. All of the above specimens were collected by F. Plaumann in 1969.

DESCRIPTION.— Form: As in figure 56. Short and broad; highly convex; with short, broad pronotum and small head. Easily distinguished from all other species in the group by the small, acute, denticulate hind angles of the pronotum.

Color: Head and body rufous, very shiny; appendages testaceous; antennal articles infuscated apically.

Head: Broad between eyes; frontal furrows moderately impressed, posteriorly divergent; eyes medium-sized and flat.

Pronotum ( Figure 57 ): Broadly transverse (W/ L, x 1.73; range, 1.64-1.85; 8 specimens); only anterior pair of lateral setigerous pores present, at anterior third; hind angles small, acute, denticu- late, sides anterior to angles evenly arcuate; side margins beaded, not reflexed.

Elytra: Smooth; side margins narrowly explanate; humeri evenly rounded; chaetotaxy formula Eo-la, 2b, 3b, 4c, 5c, 6b, 7, 8a and Ed-1, 7b, 8; plica not evident externally.

Microsculpture: Frons with large, transversely stretched meshes (as in Figure 22 d ); pronotum and elytra without microsculpture.

Secondary sexual characters: Male genitalia (Figure 63) and female genitalia (Figure 68) characteristic of the species group.

Size: Eight specimens: length, 2.0-2.5 mm; width, 1.0-1.3 mm.

NATURAL HISTORY.— Unknown, except adults collected in December. Some of the specimens are teneral, indicating, at least, that the pupal stage occurs in December.

LOCALITY RECORDS ( Figure 72 ).—I have seen eight specimens from the following locality:

SOUTH AMERICA: BRAZIL: Santa Catarina State: Nova Teutonia (MCZ, USNM).

Figures

FIGURE 22.—Scanning electron micrographs (X125O) of dorsal microsculpture. Xystosomus gruti: a, frons; b, pronotal disc; c, disc of left elytron; note serial puncture. Xystosomus turgidus: d, frons; e, pronotal disc; /, disc of left elytron. Xystosomus ovatulus: g, disc of left elytron; note serial puncture.

FIGURE 56.—Habitus of Xystosomus impressifrons, male, Lagoa de Saquarema, Brazil.

FIGURE 72.—Approximate range of the inflatus and laevis groups.

FIGURES 57-62.—Pronotum, dorsal aspect: 57, Xystosomus laevis, female, Nova Teutonia, Brazil; 58, X.paralaevis, female, Sao Paulo, Brazil; 59, X. laevimicans, female, Santos, Brazil; 60, X. niger, female, Serra Bocaina, Brazil; 61, X. tholus, male, Alto da Serra, Brazil; 62, X. turgidus, female, Rio Caraguata, Brazil.

FIGURES 63-68 Genitalia. 63-67, Male, left lateral aspect: 63, Xystosomus laevis, Nova Teutonia, Brazil; 64, X. laevimicans, Alto da Serra, Brazil; 65, X. impressifrons, Brazil; 66, X. tholns, Alto da Serra, Brazil; 67, X. niger, Serra Bocaina, Brazil. 68, Female, X. impressifrons, "Lagune de Sacuaresma," Brazil: a, bursa copulatrix; b, spermathecal reservoir.