Brachygluta (Brachygluta) infinita ( Casey, 1886 )

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 : 64-66

22. Brachygluta (Brachygluta) infinita ( Casey, 1886)

( Figs 27 , 38 B)

Bryaxis infinita Casey, 1886: 184 . Type locality: Austin, Texas. Type depository USNM, Lectotype male designated below. Brendel & Wickham 1890: 268 (as syn. of B. belfragei ). Casey 1894: 478.

Brachygluta infinita: Raffray 1904: 225 ; 1908: 231; 1911: 94. Leng 1920: 130. Bowman 1934: 83 (Group I, key), 86. Poole & Gentili 1996: 380. Chandler 1997: 55.

Material examined, 22 specimens. USA: Texas: Cameron Co.: Brownsville, V-10-1908 ( MCZC, 2); Esperanza Ranch, Brownsville, VIII ( USNM, 1). Harlingen, VIII-30-1945, D.E. Hardy & V.L. Wooley, at light ( FMNH, 2). Collingsworth Co.: 7 mi N Wellington, VI-26-1995, Godwin, Marqua & Wolfe, UV light ( TAMU, 1). San Patricio Co.: Lake Corpus Christi, 3 mi S Swinney Switch, VIII-22-1974, C.W. O'Brien, UV trap ( DSCC, 2). Travis Co.: Tex [dot under "e"] (=Austin; Lectotype and 6 Paralectotypes, USNM). Val Verde Co.: Del Rio, 955', VII-23/24, Wickham ( AMNH, 1). Only state on label: “Tex.” ( CMNH, 1); Brend, Horn Coll H9383 ( MCZC, 3, possible syntypes); Casey, ( MCZC, 1, Paralectotype). MEXICO: Nuevo León: 29 km W Linares, Santa Rosa Can.(yon), VI-3-1983, S. Peck & M. Kaulbars, UV light ( DSCC, 1).

Description. BODY: Length 1.76–2.12 mm; orange-brown; setae over dorsum short, curved and suberect, appressed on ventral surface. Head: surface shining and smooth to opaque, microreticulate and appearing roughened in a few, punctures indistinct. Antennomeres III–VII longer than wide, VIII as long as wide, IX elongate, X slightly longer than wide, VIII about one-half width of IX ( Fig. 27 C). Setose area of median vertexal fovea as wide as those of lateral foveae. Pronotum: surface smooth and shining with punctures indistinct, to opaque due to dense punctation. Setose area of median antebasal fovea same size as those of lateral antebasal foveae. Elytra: with faint microreticulation, punctures indistinct, discal stria extending to about four-fifths of elytral length. Abdomen: tergite 1 disc smooth, shining, punctures indistinct; basal striae about one-fourth paratergite length, apices difficult to distinguish, striae separated at base by one-half tergite width, with distinct setose brush between bases of striae.

MALE: Antennae and trochanters lacking modifications. Metaventrite with triangular patch of dense longer setae extending anteriorly from between metacoxae to middle of metaventrite. Tergite 1 with disc convex, apex straight, lacking modifications ( Fig. 27 A), in lateral view evenly curving to meet base of tergite 2; tergite 2 lacking obvious modifications, across most of base with low carina that is covered by apex of 1, not visible in dorsal view and challenging to recognize in posterodorsal view. Ventrites broadly convex except for ventrite 3, ventrite 3 convex in middle portion, laterally with posterior half of forming smooth ridge, anterior to ridge with deep transverse sulcus ( Fig. 27 B). Metatibiae thin, narrow at base, gradually widened to near apex, mesal margin of apical fifth with brush present ( Fig. 27 D). Aedeagus 0.32 mm long; with dorsal plate triangular; parameres curved laterally in apical portion, margins even in width to apex, with three preapical large setae on lateral margin, preapical hyaline seta near mesal margin, thickened to middle and aciculate; internal sac with three short spines, and complex broad multispined structure ( Figs 27 E–F).

FEMALE: Similar to male; metaventrite with apical triangular setose patch present but less obvious than in male. Metatibiae similar to that of male. Ventrites broadly curved.

Collection data: Three of the records indicate collection by use of ultraviolet light. Taken from May to August.

Distribution ( Fig. 38 B). There is one record from the northern portion of Nuevo León, Mexico, with the rest of the records being from central and southern Texas.

Comments. This species is unique in lacking both antennal and dorsal abdominal modifications in males, and is the only species where the male characters are ventrally placed. In males the lateral portion of ventrite 3 is smoothly ridged posteriorly and transversely sulcate at the base. Also, the metasternal triangular setose patch is distinct with dense setae; in females the metasternal setose patch is not as obvious. Casey (1894: 478) lamented that the specimens in his type series seemed to be all females, but ironically five of the 7 present at the USNM are males. The odd large multispined structure of the internal sac is shared with B. corniventris , a species that has complex male characters on tergites 1–2, and is otherwise quite dissimilar from B. infinita .

Casey indicated that he had 14 specimens from Austin, Texas as the basis for his original description, with only seven of these now present at the USNM. From these a male is here designated as the Lectotype: // Tex [dot under "e"]/Casey bequest 1925/ [red label] TYPE USNM 38692/ infinita Casy / [red label] LECTOTYPE Bryaxis infinita Casey ♂ ‘13 des. DSChandler//. Five other specimens with similar label data, and one lacking a “Tex” and USNM type labels are labeled as Paralectotypes. Seven specimens of Casey’s type series are presumed to have been dispersed to other collections. Brendel & Wickham (1890: 268) commented on B. infinita , indicating that they had seen some of Casey’s type material, and placed his species as a junior synonym of B. belfragei . One male is present in the MCZC collection, where the major portion of Brendel’s collection is held (Brendel’s primary type specimens reside in the ANSP), with a “Casey” label and identified as B. belfragei . Three other specimens, two males and a female, are present in the Horn Collection at the MCZC, bearing the labels “Tex” and “Brend”, and identified as B. infinita . The specimen with the “Casey” label is here labeled as a paralectotype, and the other three are labeled as possible syntypes.

Figures

FIGURE 27. Brachygluta infinita (Casey). A: Abdomen, dorsal view (lectotype). B: Abdomen, left side, ventrites 1 – 3, laterocaudal view (lectotype). C: Right antenna (lectotype). D: Left metatibia, anterior view (lectotype). E: Aedeagus (paralectotype). F: Aedeagus, internal sac (paralectotype, other specimen).

FIGURE 38. Distribution map of Brachygluta corniventris species-group and Brachygluta infinita species-group. A: Brachygluta corniventris (Motschulsky), also mentioned generically from Canada (very likely from southern Ontario). B: Brachygluta infinita (Casey). (Red dot: material examined, green dot: only state on label).