Brachygluta (Brachygluta) chisos Sabella

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 : 68

24. Brachygluta (Brachygluta) chisos Sabella , sp. n.

( Figs 29 , 42 A)

Material examined, HOLOTYPE male: USA: Texas: Brewster Co.: //Big Bend N. P., TEX. 1850', Boquillas, May 17, 1959. Light, Howden & Becker/ [red label] HOLOTYPE Brachygluta chisos Sabella // ( CNCI).

Description. BODY: Length 1.84 mm; orange-brown with elytra lighter; head and pronotum with setae short, decumbent, over rest of body longer. Head: surface smooth, shining, punctures indistinct. Antennomeres III–VI longer than wide, VII, VIII slightly transverse, IX as long as wide, X wider than long, VIII about four-fifths width of IX ( Fig. 29 C). Setose area of median vertexal fovea as large as those of lateral foveae. Pronotum: surface smooth, shining, punctures indistinct. Setose area of median antebasal fovea about two-thirds width of lateral antebasal foveae. Elytra: with faint microreticulation, punctures indistinct, discal stria extending to about fourfifths of elytral length. Abdomen: disc smooth, shining, punctures indistinct. Basal striae of tergite 1 about onethird paratergite length, slightly divergent, separated at base by one-half tergite width, setose brush between bases of striae distinct, long.

MALE: Antennae and trochanters unmodified, simple. Metaventrite with middle of disc flattened through length, with dense long setae in this area; tergite 1 with disc smoothly swollen to middle, apex broadly and smoothly convex ( Fig. 29 A), in lateral view apex of tergite curving down to disc of tergite 2; tergite 2 with mediobasal area semicircular, roughened and slightly impressed, about one-third width of disc, with low transverse carina at base just below apex of tergite 1, carina about one-third tergite width ( Fig. 29 B), in lateral view with disc of 1 confluently curved with following tergites. Abdominal ventrites broadly rounded. Metatibiae thin, narrow at base, gradually widened to near apex, mesal margin of apical fourth with brush present ( Fig. 29 D). Aedeagus 0.40 mm long; dorsal plate with broad triangular base, margins in apical half constricted to form sharply pointed curved apex; parameres with distinct preapical constriction, three thick setae on lateral margin at basal angle of constriction, flattened preapical hyaline setae near mesal margin widening to middle, apex aciculate; internal sac with two large spines, both only slightly curved ( Fig. 29 E).

FEMALE: Unknown.

Collecting data. The holotype was collected in May at light.

Distribution ( Fig. 42 A). This species is known only from western Texas (Big Bend National Park).

Comments. This species shares with B. kiowa the indistinct/flattened/impressed roughened area in the basal portion of the disc of tergite 2, but in B. chisos this area is narrower and extends only to the middle of the disc, while in B. kiowa it extends nearly the length of the tergite and two impressions are often distinct at the middle of this area.

Etymology. The name is that of one of the indigenous groups known from this area.

Figures

FIGURE 29. Brachygluta chisos Sabella (Texas, Brewster Co., 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.