Eupsenius LeConte, 1849

Chandler, Donald S., 2023, The Eupsenius LeConte of North America and the Lesser Antilles with Notes on the Brachyglutini Subtribes Eupseniina Park and Baradina Park (Coleoptera: Staphylinidae: Pselaphinae), The Coleopterists Bulletin 77 (3), pp. 397-412 : 400-401

Eupsenius LeConte, 1849

Eupsenius LeConte 1849: 90 . Type species, Eupsenius glaber LeConte, 1849 , by original monotypy. LeConte 1863a: 21. LeConte and Horn 1883: 88. Raffray 1890: 120, 125. Raffray 1904: 253. Raffray 1908: 254. Raffray 1909: 35. Raffray 1911: 110 (world catalog). Brendel and Wickham 1891: 2. Leng 1920: 131 (North American catalog). Bowman 1934: 115. Park 1942: 128 (key to Neotropical species). Park 1954: 19. Park et al. 1976: 63 (key to NA and Caribbean species). Newton and Chandler 1989: 45. Carlton 1990: 575–576. Chandler 1990: 1183. Chandler 1997: 69 (North American catalog). Chandler 1999: 172. Chandler 2000: 22, 81. Chandler 2002: 52, 67, 95. Peck and Thomas 1998: 40 (Florida checklist, county records). Newton et al. 2005: 39 ( Colombia checklist).

Euplenius (error) Motschulsky 1855: 16

Eupsinus (error) Motschulsky 1856: 7.

Euprenius (error) Raffray 1897: 262.

Diagnosis. Body asetose except for certain ventral areas and appendages, glabrous and polished in dorsal view, apical three antennomeres densely setose; antennomere XI long and with apex bluntly pointed, one-third to nearly one-half of total antennal length; gular disc smoothly curved, lacking median longitudinal carina; ocular-maxillary carinae forming prominent lateral ridges of head venter; lacking proventral foveae; lateral antebasal foveae of pronotum punctiform or lacking, pronotal antebasal sulcus thin and weakly defined to partial- ly or completely lacking, position indicated by internal ridge.

Generic Redescription. Body length 0.90–2.03; polished, glabrous in dorsal view, dense setae present on antennomeres IX–XI, maxillary palpi with dense, short setae, femora and tibiae with moderately dense, appressed, short (0.01–0.02) setae; anterior margin of mesoventrite with dense setae, distinct fringe on posterior margin of mesoventrite and on posterior margin of first abdominal ventrite.

Head with deep dorsal tentorial pits, pits with short setae at bottom; postantennal notches small, lacking vertexal sulci; head base with median indentation variably distinct, with ocular-antennal, ocular-mandibular, and ocular-maxillary carinae present; gula with short median carina at anterior margin, gular disc convex; ventral tentorial pits small, widely separated. Antenna straight, not geniculate, with antennomeres III–VIII narrow, transverse, subequal in width, IX–X wider and transverse, IX–XI forming distinct club, XI elongate, varying from just more than one-third total antennal length to nearly half, slightly inflated medially. Maxillary palpi with second and third segments same width, fourth segments weakly securiform, widest at apical point of basal third.

Prothorax with pronotal disc convex, lateral margins evenly curved to basal constriction in dorsal view, constricted portion about one-third total length, antebasal sulcus varying from lacking to weakly indicated, often only sulcate laterally, line of sulcus indicated by dark internal carina through width, smooth limited median antebasal impression usually present, lateral antebasal foveae either lacking or indicated by tiny pit. Lacking lateral carinae, pronotum smoothly merging with proventrite, lacking proventral foveae, with dense setal brush across proventrite in some Neotropical species.

Elytron with two large, setose basal foveae, lacking discal striae, lacking subhumeral fovea and carina, lateroapical cleft reduced to fold. With large lateral mesoventral foveae meeting internally, short and broad median mesoventral fovea broadly meeting lateral mesoventral fovea, mesoventrite with prominent short median carina, with distinct setose fringe extending from posterior margin of mesoventrite; lateral mesocoxal fovea present, deep setose impression at anterior margin of metaventrite extending laterally; with single median metaventral fovea. Metaventrite large, with weak median sulcus on apical half.

Legs with single tarsal claw, anterior claw lacking or small, pro- and mesofemur clavate, metafemur weakly clavate. Metacoxa with apex of trochanteral articulation slightly protruding, metacoxa otherwise flat.

Abdominal tergites 1–3 with narrow paratergites distinct, tergite 1 with short discal striae, striae positioned at about one-third points, tergite 1 with distinct basolateral foveae, tergites 2–4 with shallow basolateral impressions, tergite 1 nearly as long as 2–5 together in dorsal view; ventrite 1 thin, with distinct posteriorly directed setal fringe, ventrite 2 with basomedial and basolateral foveae, ventrites 3–5 short, together about as long as 2, 6 nearly as long as 2.

Male with seven ventrites, ventrite 7 transverse, small, easily overlooked; ventrite 6 with median impression that varies in depth/distinctness between species. North American species have two extreme forms for male genitalia: 1) strongly curved tube with simple apex, internal sac large, striate, obscuring apex; 2) less curved from base to broadly wid- ened and complexly shaped apex, internal sac not obscuring apex; intermediate or variant forms seen for some Central American species.

Female with six ventrites, ventrite 6 with disc shallowly convex.

Biology/Collection Techniques. The majority of North American specimens have been taken by pas- sive collecting techniques such as light traps, flight intercept traps, and Malaise traps. The traditional active collecting technique for pselaphines is sifting followed by processing the reduced leaf and rotten wood litter using Berlese/Tullgren funnels. While large numbers of Eupsenius species have been taken from leaf litter samples in Mexico, Central America, and the Caribbean island nations, such sampling in North America has been notably non-productive, though scattered specimens have been taken from a variety of different leaf litters or from “forest litter”. Tim King (Highland Lake, AL) has taken many individuals of E. dilatatus near his home by sifting/ Berleseing forest litter and using window and ultraviolet light traps.