Xystosomus nigripalpis, 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 : 9-10

3. Xystosomus nigripalpis , new species

FIGURES: 8, 25, 69

TYPE-LOCALITY.— Barro Colorado Island, Canal Zone, Panama.

TYPE-SPECIMENS.—The holotype male and allotype are in USNM. These and the paratypes were collected by my wife and me in 1971. Paratypes (21): CAS , 2; BMNH, 2; MCZ, 2; MHNP, 2;

UASM, 2; USNM, 11.

DESCRIPTION.—Form: As in X. gruti except elytra slightly more convex. Easily distinguished by the piceous palpi, the nearly black integument of the dorsal surface, and the highly convex lateral intervals of the elytra.

Color: Head and body nigropiceous; pronotum and elytra strongly iridescent; appendages partially infuscated; antennae and tarsi testaceous; palpi except apical article almost black.

Head: Frontal furrows moderately impressed; eyes large and prominent.

Pronotum ( Figure 8 ): Transverse (W/ L, x 1.56; range, 1.47-1.65; 10 specimens); hind angles slightly obtuse, sides anterior to angles straight; side margins narrowly explanate basally, beaded anteriorly.

Elytra: Striae 1-8 of each elytron well impressed and punctulate to apical third, shallowly impressed and nonpunctulate in area of recurrent groove, lateral four striae more deeply impressed and more coarsely punctulate than discal striae, especially near base; lateral intervals convex to at least middle, flattened gradually to apical third, discal intervals less convex, at least in apical two-thirds; side margins broadly explanate; humeral projection moderately developed, well rounded; chaetotaxy as in X. gruti ; plica small, evident externally.

Microsculpture: As in X. gruti .

Secondary sexual characters: Male genitalia characteristic of the group (Figure 25). Female genitalia characteristic of the species group.

Size: Ten specimens: length, 3.3-3.9 mm; width, 1.5-1.8 mm.

NATURAL HISTORY.— The type series was collected in and on deep litter at the crown of a fallen tree in the humid, tropical, semideciduous forest of Barro Colorado Island, Panama. The individuals were very active in sunlight (sparse as it was in this part of the forest) and shade, commonly running over undisturbed leaves and twigs. Most specimens were found in the deep leaf litter where the leaves were wilted but not decomposed. Our method of raking and reraking the leaves knocked most specimens to the soil, but close observation showed the beetles to be among the leaves off the

soil. No specimens were teneral. All of these beetles were collected alive and taken to Washington for behavior studies and breeding purposes, the results of which will be published separately. (See also X. gruti , under Behavior.) I have observed captive specimens in flight.

LOCALITY RECORDS ( Figure 69 ).—I have seen 23 specimens from the following locality:

CENTRAL AMERICA: PANAMA: Canal Zone, Barro Colorado

Island.

Figures

FIGURE 69.—Approximate range of the gruti group.

FIGURES 7-21.—Pronotum, dorsal aspect: 7, Xystosomus ampliatus, female, Hamburg Farm, Costa Rica; 8, X. nigripalpis, female, Barro Colorado Island, Panama; 9, X. strigosus, female, Rio Parahyba, Brazil; 10, X. iris, female, Cochabamba, Bolivia; 11, X. sculpticollis, female, Teffe, Brazil; 12, X. negrei, male, Rancho Grande, Venezuela; 13, X. aetholius, female, Cochabamba, Bolivia; 14, X. anterocostis, Hamburg Farm, Costa Rica; 15, X. sublaevis, male, Rio Banano, Costa Rica; 16, X. sulcicostis, female, Volcan de Chiriqu!, Panama; 17, X. apicisulcatus, female, Minas, Brazil; 18, X. batesi, female, Petr6polis, Brazil; 19, X. seriatus, female, Nova Teutonia, Brazil; 20, X. ovatulus, female, Caraca, Brazil; 21, X. grossipunctatus, female, Caraca, Brazil.