Brachygluta (Brachygluta) seri Chandler

Chandler, Donald S., Sabella, Giorgio & Bückle, Christoph, 2015, A revision of the Nearctic species of Brachygluta Thomson, 1859 (Coleoptera: Staphylinidae: Pselaphinae), Zootaxa 3928 (1), pp. 1-91 : 66-68

23. Brachygluta (Brachygluta) seri Chandler , sp. n.

( Figs 28 , 42 D)

Material examined, HOLOTYPE male: MEXICO: Baja California: // MEXICO: Baja Calif. Norte, Isla San Esteban, main canyon wash, east side, VII-28/29 -86, R.L. Aalbu., BL/ [red label] HOLOTYPE Brachygluta seri Chandler ( CSCA).

Description. BODY: Length 2.20 mm; brown with elytra and appendages orange-brown; setae over body decumbent, longest on abdomen. Head: surface smooth, shining, lightly microreticulate, punctures indistinct. Antennomeres III–VI longer than wide, VII as long as wide, VIII–X transverse, VIII about two-thirds width of IX ( Fig. 28 C). Setose area of median vertexal fovea as large as those of lateral foveae. Pronotum: surface shining, lightly microreticulate, punctures indistinct. Setose area of median antebasal fovea about two-thirds width of lateral antebasal foveae. Elytra: microreticulate, surface granulate, punctures indistinct, discal stria faint, extending to about three-fourths of elytral length. Abdomen: disc with small, distinct punctures, basal two tergites opaque due to distinct microreticulation, apical tergites more shining; basal striae of tergite 1 short/indistinct, separated at base by about three-fifths tergite width; setose comb at base between basal striae sparse.

MALE: Antennae and trochanters lacking modifications, simple. Metaventrite with rounded-triangular area extending anteriorly from metacoxae to anterior portion of disc, area with dense long setae, metasternal disc laterally with setae distinct but becoming sparser. Tergite 1 distinctly microreticulate across disc, apical margin slightly concave, with broad impression in basal third of disc ( Fig. 28 A); in lateral view tergite apex slightly protruding out over tergite 2; tergite 1 only slightly longer than tergite 2. Tergite 2 with semicircular basal carina in median fourth just covered by apex of tergite 1; tergites 2-3 slightly and broadly impressed at middle across width ( Fig. 28 B). Ventrites broadly rounded. Metatibiae thin, narrow at base, gradually widened to near apex, mesal margin of apical fifth with brush present ( Fig. 28 D). Aedeagus 0.40 mm long; dorsal plate rounded triangular, margins evenly converging to bluntly rounded point; parameres rounded at apex, three thick setae on lateral margin at angle of distinct preapical constriction; thickened hyaline seta on mesal margin, longer than preapical setae, thickened to middle, with acute apex; internal sac with four curved large spines ( Fig. 28 E).

FEMALE: Unknown.

Collecting data. The holotype was taken at blacklight in July.

Distribution ( Fig. 42 D). Found on a desert island near the middle of the Gulf of California.

Comments. This species shares with B. cochimi the relatively long tergite 2, which in that species is clearly two-thirds the length of tergite 1, and their occurrence on islands in the Gulf of California. It may be separated from B. cochimi by the distinct basal depression of tergite 1 and the lack of a discal impression on tergite 2; for B. cochimi the disc of tergite 1 is smoothly convex to the base, and tergite 2 has a visible transverse basal impression.

Etymology. The name originates from the Seri indigenous people, which historically have lived on San Esteban Island in the Gulf of California.

Figures

FIGURE 28. Brachygluta seri Chandler (Mexico, Baja California, Isla San Esteban, holotype). A: Abdomen, dorsal view. B: Abdomen, caudal view. C: Right antenna. D: Left metatibia, anterior view. E: Aedeagus.

FIGURE 42. Distribution map of Brachygluta seri species-group and Brachygluta mormon species-group. A: Brachygluta chisos Sabella. B: Brachygluta klamath Bückle. C: Brachygluta cochimi Bückle. D: Brachygluta seri Chandler.