Brachygluta (Brachygluta) eldredgei 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 : 48-49

15. Brachygluta (Brachygluta) eldredgei Chandler , sp. n.

( Figs 20 , 40 A)

Material examined, 11 specimens. HOLOTYPE male: USA: California: Mono Co.: // USA: California: Mono Co., Mono Lake, Navy Beach, 12.VI.2008, KTE08-156, taken with ants under rock, leg. K.T. Eldredge/ [red label] HOLOTYPE Brachygluta eldredgei Chandler // ( FMNH). PARATYPES, 10: eutopotypical ( DSCC, 2M 4F; SEMC, 3F). Arizona: Cochise Co. : Cochise Stronghold, Dragoon Mts. , IX-3 /7-1969, R.J. Shaw, UV light trap ( UAIC, 1M).

Description. BODY: Length 1.96–2.02 mm; red-brown to brown with red-brown elytra; head and pronotum with setae short, curved and suberect, over rest of body setae decumbent. Head: surface smooth, shining, punctures indistinct. Antennomeres III–VII longer than wide, VIII as long as wide, IX elongate, X transverse, VIII about three-fourths width of IX ( Fig. 20 C). Setose area of median vertexal fovea slightly narrower than those of lateral foveae. Pronotum: surface smooth, shining, punctures indistinct. Setose area of median antebasal fovea slightly smaller than those of lateral antebasal foveae. Elytra: with faint microreticulation, punctures indistinct, discal stria extending to about four-fifths of elytral length. Abdomen: tergite 1 with disc smooth, shining, punctures indistinct; basal striae of tergite 1 straight, about one-third paratergite length or less for male, about one-fifth paratergite length for female, separated at base by about two-fifths tergite width, with distinct long but sparse setose brush between bases of striae.

MALE: Antennae and trochanters unmodified, simple. Metaventrite impressed from middle to apex, impression covered with setae that are longer and denser. Tergite 1 elongate, length nearly equal to width of disc, broadly emarginate at apex, apex deflexed in narrow zone that has thicker red-brown setae denser than on disc; tergite 2 with middle half lacking setae, with slightly arcuate transverse carina at center of disc, margins of seta-free area slightly converging posteriorly, lateral portions of tergite with short thick golden setae, area opaque due to dense punctation ( Figs 20 A–B); in lateral view tergite 1 protruding slightly over base of tergite 2; tergites 3–4 with short thick golden setae, setae sparser, not as densely punctate; in lateral view with tergites forming evenly curved outline, but with deep grooves between tergites 1–2 and 2–3. Ventrites broadly convex. Metatibiae thin, narrow at base, gradually widened to near apex, mesal margin of apical fourth with brush present ( Fig. 20 D). Aedeagus 0.37 mm long; dorsal plate triangular, with preapical constriction of margins to form acutely pointed apex; parameres with three thick setae on lateral margin at basal angle of preapical constriction, with preapical hyaline seta near mesal margin, thick basally, aciculate apically; internal sac with three thick curved spine ( Fig. 20 E).

FEMALE: Metaventrite with setae similar over breadth; lacking abdominal modifications, tergites gently convex; ventrites broadly curved. Metatibiae similar to those of male.

Collecting data. Found in association with a colony of Pogonomyrmex ants under rocks along the margin of an alkaline lake, and one specimen was collected using an ultraviolet light trap. The specimens were taken in June and September.

Distribution ( Fig. 40 A). Only known from California at the western margin of the Great Basin, and also from eastern Arizona.

Comments. The relatively long tergite 1 that is broadly emarginate at the apex, together with the thicker and shorter setae present on the deflexed apex of tergite 1 and also across tergite 2, places this species in the texana species-group. This species is easily separated from the other species by the broad transverse impression of tergite 2 that has an arcuate transverse carina at the middle of the tergite. The other two species in this group lack this feature, but have a small bump at the center of tergite 2 with two oblique sulci to each side.

Etymology. Named for K. Taro Eldredge, collector of all but one specimen of the type series.

Figures

FIGURE 20. Brachygluta eldredgei Chandler (California, Mono Co., paratype). A: Abdomen, dorsal view. B: Abdomen, tergite 1 – 3, caudal view. C: Right antenna. D: Left metatibia, anterior view. E: Aedeagus.

FIGURE 40. Distribution map of Brachygluta texana species-group. A: Brachygluta eldredgei Chandler. B: Brachygluta foveata (LeConte). C: Brachygluta texana (Casey). (Red dot: material examined, green dot: only state on label).