Brachygluta (Brachygluta) lareaui 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 : 43-44

13. Brachygluta (Brachygluta) lareaui Chandler , sp. n.

( Figs 16–17 , 39 B)

Material examined, Holotype male: USA: South Carolina: Charleston Co.: // USA: SC: Charl. Co., Mt. Pleasant, V-22-2007, R. Lareau, UV lt./ [red label] HOLOTYPE Brachygluta lareaui Chandler ( FMNH).

Description. BODY: Length 2.60 mm; orange-brown; setae on head and pronotum short, curved and suberect, depressed to appressed over rest of body. Head: surface smooth, shining, punctures indistinct. Setose area of median vertexal fovea slightly smaller than those of lateral vertexal foveae. Antennomere form treated below under male characters. Pronotum: surface opaque due to light microreticulation, punctures indistinct; setose area of median antebasal fovea about two-thirds width of those of lateral antebasal foveae. Elytra: surface lightly microreticulate, punctures indistinct. Discal stria extending to about four-fifths of elytral length. Abdomen: tergite 1 with surface shining, punctures small but distinct. Basal striae of tergite 1 elongate, extending about one-third paratergite length, striae separated at base by about one-half tergal width, setal brush between bases of striae sparse but distinct.

MALE: Antennae relatively elongate, antennomere III longer than wide, IV as long as wide, V–VI enlarged, V dorsoventrally flattened, in dorsal view IV about two-thirds width of V, in lateral view IV about three-fourths width of V, VI as wide as IV, roughly cylindrical and longer than wide, VII clearly longer than wide, VIII slightly longer than wide, IX–X elongate, both about half again as long as wide (antennomeres X–XI of right antenna partially fused) ( Fig. 17 A). Metaventrite with apical half at middle slightly impressed, setae slightly denser in impression than laterally. Lacking modifications of trochanters, ventral margins smooth. Tergite 1 with apex protruding blunt medial angulation; margin of angulation extending above tergite 2, with row of setae ventrally longest at middle, area of tergite 2 ventral to angulation with setae short and appressed ( Figs 16 A–B); in lateral view tergite 1 horizontal, apex deflexed, tergite 2 flat and nearly level, well-separated from 2 ( Fig. 16 C). Abdominal ventrites 2–6 flattened medially. Metatibiae narrow at base, evenly thickening to middle and then narrowing slightly to apex, apical third of metatibiae straight, with thick setal comb on mesal margin in apical fifth ( Fig. 17 B). Aedeagus 0.46 mm long; with dorsal plate narrowly triangular, apex acutely pointed; parameres with three small thin setae at posterior margin of preapical constriction, hyaline setae large, broadly flattened, widest at middle and gradually tapering to acute point; internal sac with two large and one small spines, one large spine strongly curved ( Fig. 17 C).

FEMALE: Unknown.

Collecting data. The holotype was collected at ultraviolet light.

Distribution ( Fig. 39 B). Only known from South Carolina near the Atlantic coastal salt marshes.

Comments. This is a distinctive species in that the male antennae are modified, while the abdominal tergal modifications are typical of the dentata species-group. The antennomeres are all elongate except for swollen antennomere V, which is a pattern not found in any other New World species, where VIII is always transverse or about as long as wide, and IX–X are never so clearly elongate. The bluntly angular apex of tergite 1 is close in form to that of B. dentata , but the medially swollen metatibiae and modified antennae readily separate B. lareaui from this and all other species.

Etymology. Named for Richard Lareau, who brought this specimen to the attention of DSC after he posted a photo of it on the BugGuide website, and then kindly sent it to him when notified that it was the first known specimen of an undescribed species.

Figures

FIGURE 16. Brachygluta lareaui (South Carolina, Charleston Co., holotype). A: Abdomen, dorsal view. B: Abdomen, caudal view. C: Abdomen, lateral view.

FIGURE 17. Brachygluta lareaui Chandler (South Carolina, Charleston Co., holotype). A: Right antenna. B: Left metatibia, anterior view. C: Aedeagus.

FIGURE 39. Distribution map of Brachygluta dentata species-group. A: Brachygluta dentata (Say) (excluding Texas and Illinois, see text). B: Brachygluta lareaui Chandler. C: Brachygluta tamaulipec Sabella. (Red dot: material examined, green dot: only state on label).