Trogastrini Jeannel, 1949

Owens, Brittany E. & Carlton, Christopher E., 2016, Collecting in the Museum: New Species, Taxonomic Changes, and Range Extensions of Euplectite Pselaphinae (Coleoptera: Staphylinidae) of the Southeastern United States, The Coleopterists Bulletin 70 (3), pp. 611-633 : 611-633

Tribe Trogastrini Jeannel Subtribe Rhexiina Park Rhexius LeConte, 1849

Diagnosis. Males. Head: Tempora broadly rounded and abruptly constricted behind ocular canthus to cervical constriction, giving head broadly transverse appearance in dorsal view, vertexal foveae obvious, setose, located posterior to shallow, ovate frontal depression extending between antennal acetabula; antennal acetabula remote, antennomere 1 elongate (as long as segments 2– 7), antennomeres 2–8 unmodified, antennomeres 9–11 forming loose club, labrum of normal form for tribe, bearing pair of sensory pegs, mandibles broadly sickle-shaped, maxillae and labium typical for subfamily, labial palpi minute, 2-segmented, maxillary palpi unmodified, palpomere 1 minute and obliquely joined to palpomere 2, palpomere 2 pedunculate, narrower in basal 1/3, slightly expanded and rounded distally, palpomere 3 subtriangular, palpomere 4 widest, unmodified, bearing apical palpal cone; gula simple, rounded anteriorly, possessing paired gular foveae and welldeveloped gular carina; genal setae fine, dense; eyes well-developed, comprised of about 50 facets each. Thorax: Pronotum rounded, obcordate, bearing obvious midlongitudinal sulcus and antebasal transverse sulcus, lateral antebasal fovea present, prosternum concave to receive genae, lateral procoxal foveae present; mesoventrite with paired lateral mesoventral and mesocoxal fovea, single median mesoventral foveae present; metaventrite afoveate; all coxae contiguous, legs variously modified; elytra with sutural fovea and striae, antebasal discal foveae and subhumeral foveae present, discal striae very short; lateroapical cleft present; wings present. Abdomen: Tergite II with small antebasal foveae, possessing basal, transverse pubescent depression; ventrites III–VI variable; ventrite VII variously modified. Genitalia: Robust and simple, composed of a basal bulb bearing sclerotized apical extensions.

Females. Similar in form to males with the following exceptions: eyes smaller, with fewer facets; absence of secondary sexual modifications to the legs and abdominal ventrites (revision, Chandler 1990).

Notes. This genus was last revised for North America by Chandler (1990). Rhexius is a predominantly Neotropical genus with the majority of species in South and Middle America. Seven species are found in the southeastern USA. The majority of US species have broad ranges throughout the eastern US. Rhexius ouachita Chandler is known from Oklahoma and Arkansas, and Rhexius stephani Stephani occurs in Oklahoma, Illinois, and Texas. Specimens have been collected from a variety of habitats, including various forest litters, grass roots, flood debris, sphagnum moss, and rotten wood. Specimens of some species have also been obtained from flight intercept traps and by light trapping ( Chandler 1990). Like species of Conoplectus , members of Rhexius inhabit marginal, transient habitats in addition to mature forests.

The two new species described here are both from type localities in Great Smoky Mountains National Park in Tennessee. Rhexius amyae new species is known from five specimens collected from Blount, Swain, and Sevier Counties. Rhexius jaceus new species is known from a single specimen from Blount County. Although several other species within the genus have been collected from nearby North Carolina and Alabama, only these two species are known from Tennessee.

KEY TO MALES OF THE SOUTHEASTERN NORTH AMERICAN SPECIES OF RHEXIUS LECONTE (Modified from Chandler 1990)

1. Males lacking laterobasal depression of abdominal ventrite III, vertical shelf at base absent; eyes of female with 10–20 facets....2

1′. Males with laterobasal area of ventrite III impressed, vertical shelf at base apparent and extending ventrally to apex of ventrite II; eyes of female with number of facets variable.................................................... 3

2. Male eyes moderate in size, with 25–40 facets, metatibia slightly swollen medially; female ventrite VI flattened medially .......................... ..................................... R. stephani Chandler

2′. Male eyes large, with about 48 facets, metatibia swollen medially, anterior face of swollen area impressed; female ventrite VI with vague circular impression throughout length ...................... R. substriatus LeConte

3. Males with vertical shelf at base of laterobasal impression narrow but distinct; eyes of females with about 47 facets; ventrite VI vaguely impressed along base, convex at middle........... ........................................ R. ferrugineus Casey

3′. Males with vertical shelf at base of laterobasal impression obvious, wide; number of facets in eyes of females and form of ventrite VI variable......................................4

4. Aedeagus with apex of median lobe bifurcate or divided into 3 distal processes.........5

4′. Aedeagus with apex of median lobe not divided distally, apex strongly curved distally.............. 7

5. Apex of median lobe bifurcate, forks similar in form, hairy lobe to right at phallobase apex............................... R. schmitti Brendel

5′. Apex of median lobe divided into 3 small processes distally, rest of genitalia formed differently.....................................................6

6. Ventral lobe of aedeagus flattened with semicircular internal fold of right margin, lacking curved frontal accessory process ( Fig. 13c ).... ..................... R. amyae Owens and Carlton , new species

6′. Ventral lobe of aedeagus flattened, lacking any kind of marginal infolding, frontal accessory process curving to the left ( Fig. 14 ) ...... R. jaceus Owens and Carlton , new species

7. Aedeagus with ventral lobe strongly angulate to right at apex, penis curved to left; eyes of female with 36–50 facets ......... R. insculptus LeConte

7′. Aedeagus with strong, preapical, dorsal tooth, apical portion truncate, hairy lobe to left

14) Rhexius jaceus , aedeagus, dorsal view; 15) Conoplectus susae , aedeagus, dorsal view.

of phallobase; eyes of female with 10– 20 facets .................... R. ouachita Chandler

Figures

Figs. 13–15. 13) Rhexius amyae - a) Habitus, dorsal view, b) Habitus, lateral view, c) Aedeagus, dorsal view;