Xestipyge geminatum (LeConte)

Warner, William B., 2021, A brief review of the New World Xestipyge Marseul (Coleoptera: Histeridae: Dendrophilinae: Paromalini) with description of a new species from the southwestern USA, Insecta Mundi 2021 (854), pp. 1-12 : 6-7

Xestipyge geminatum (LeConte)

Figures 2 , 5 , 19

Carcinops geminatus J.E. LeConte 1859: 314 . Type locality: New York; Marseul 1862: 18.

Paromalus geminatus: Horn 1873: 306 ; Blatchley 1910: 616.

Xestipyge geminatum: Lewis 1905: 37 ; Downie and Arnett 1996: 614; Bousquet and Laplante 2006: 220.

Diagnosis. Head with disc weakly depressed, with scattered fine punctures in addition to ground punctuation. Pronotum with coarse punctures scattered throughout, though less densely so towards middle; basal marginal puncture row present but subconfused with other coarse punctuation. Elytron with inner subhumeral noticeably weaker than dorsal striae, normally extending to and sometimes fusing with humeral stria, but usually lacking on humerus; outer subhumeral stria obsolete to sometimes represented medially by irregular puncture line, occasionally present near apex as well; dorsal intervals usually noticeably weakly concave, intervals between second dorsal and sutural stria usually with scattered punctures in about apical half (less commonly coarser punctures only extending to apical quarter or so), apical declivity with aciculations variably present, often lacking entirely; sutural stria usually effaced in basal quarter or third, sometimes more or less continuous represented in that area as irregular line of punctures without strial depression. Metasternum lateral to stria with coarse punctures dense (often subcontiguous), mostly separated by less than half their own widths; lateral metasternal stria variable: complete to metatrochanter or variably effaced in posterior quarter or third. In male: tegmen with parameres about as long as basal piece, apical angular prominence obtuse and only slightly expanded just before shortly (nearly) rounded apex leaving parameral outline nearly parallel-sided, width about 1⁄9 length. Female pygidium often with vague and shallow chevron-shaped depression in apical half, but usually lacking incised chevron on disc, incised chevron when rarely present usually incomplete or weakly impressed.

Length: 1.9–2.5 mm; total length: 2.1–3.3 mm; widest width: 1.6–2.0 mm.

Range. Mazur (2011), and Bousquet and Laplante (2006) list the distribution as USA: New York, eastern N America from Quebec and Ontario to Texas and Florida. I have examined specimens from AR, IN, LA, MA, MO, NE, OH, OK, PA, TX, WI.

Habits. Bousquet and Laplante (2006) mention collections from tree hollows, sifting leaves, and in carrion; in addition to those habitats, I have seen specimens with ecological data including cow dung, under bark of logs, Berleses of flood debris and deciduous litter, and others from cross vane panel traps, flight intercept traps and Lindgren funnel traps.

Remarks. Xestipyge geminatum shares with X. conjunctum general facies including (usually) effacement of a portion of the elytral sutural stria, as well as similar distribution. However, females of X. conjunctum have a distinctly incised chevron on the pygidial disc that is nearly always lacking in X. geminatum . Male X. geminatum have nearly parallel-sided parameres, lacking the apical expansion present if parameres of other New World species, and both sexes of X. geminatum differ by having the lateral metasternal faces more densely punctate, the elytral dorsal intervals weakly but (usually) noticeably concave and the inner subhumeral stria usually complete from apex to the humeral umbone (vs. usually effaced in the basal half in X. conjunctum ).

Figures

Figures 1–2. Dorsal habitus of Xestipyge species. 1) X. conjunctum, SC, USA. 2) X. geminatum, NC, USA.

Figures 3–5. Xestipyge species. 3) X. conjunctum, SC, USA, female pygidium. 4) X. conjunctum, right elytron. 5) X. geminatum, NC, USA, right elytron.

Figures 15–19. Xestipyge species tegmena, dorsal view. 15) X. garbigliettii, Durango, Mexico. 16) X. multistriatum, Veracruz, Mexico. 17) X. conjunctum, SC, USA. 18) X. skelleyi, holotype. 19) X. geminatum, NC, USA.