Oropodes dybasi Grigarick & Schuster, 1976

Chandler, Donald S. & Caterino, Michael S., 2011, A taxonomic revision of the New World genus Oropodes Casey (Coleoptera, Staphylinidae, Pselaphinae), ZooKeys 147, pp. 425-477 : 434-435

2. Oropodes dybasi Grigarick & Schuster, 1976 Figs. 323Map 1

Oropodes dybasi Grigarick & Schuster, 1976: 101; Chandler 1997: 15. Type locality: Oregon, Benton County, Well’s Creek, 9 mi SW Philomath. Holotype male (FMNH).

Specimens examined.

23, all DSC except where indicated: OREGON: Benton County: 8 mi W Philomath, 1000', V-12-1983, D.S. Chandler, sift forest leaf litter; McDonald Forest, Sulfur Springs Road, II-3-1973, G.L. Peters. Lane County: all H.J. Andrews Experimental Forest: Road 134, 1750', Watershed 10, I-24-1981, G. Cassis, site 4, 1975 clearcut, Pseudotsuga litter; Road 1506, 2500', L301A, III-12-1981, G. Cassis, site 9, 1954 clearcut, Pseudotsuga / Rhododendron litter; R.S. 7, 1450', V-13-1983, D. S. Chandler, old growth, sift Douglas-fir leaf litter & moss; Road 130, 1750', V-12-1984, D. S. Chandler, old growth, sift cedar litter by stream; Lookout Creek, 1950', V-13-1984, D. S. Chandler, old growth, sift bigleaf maple litter; Road 1506, 3500', V-14-1984, D. S. Chandler, old growth, berlese moss by stream; R.S. 20, 2250', Road 134, V-12-1984, D. S. Chandler, old growth, sift Douglas-fir leaf litter; Road 350, 4050', V-11-1984, D. S. Chandler, old growth, sift Douglas-fir leaf litter; Road 1506, 1900', Lookout Creek, X-27-1982, G. L. Parsons, site 6, 1963 clearcut, litter; Road 1506, 1900', Lookout Creek, VII-6-1982, X-27-1982, V-11-1983, X-26-1983, G. L. Parsons, site 7, 1954-55 clearcut, litter; Road 1506, 1800', IX-6-1982, G. L. Parsons, site 31, 1950 clearcut, litter. Linn County: 6 mi W Crawfordsville, 1200', IX-15-1973, E.M. Benedict, bigleaf maple duff (DSC, CNCI). Additional specimens from the H.J. Andrews Experimental Forest are in the Oregon State University Collection.

Description.

Length 1.88-2.04. Body light orange-brown. Eyes of both sexes with 20-32 facets. Antennomere V larger than those adjacent, V-VIII quite transverse, IX narrower than X. Pronotum with medial sulcus shallow. Abdomen with carinae of first ventrite extending from posteromesal margin of metacoxal cavities posteriorly to ventrite apex.

Males: Metasternum with broad median longitudinal impression. Legs (Fig. 3B): profemora not modified, protibiae angulate on inner margin at point one-third distance from base swollen from there to apex, inner margin broadly concave from angulation to apex; mesotibiae with small apical spine on mesal margin; metatrochanters with acute spine on ventral margin (Fig. 3G), metatibiae with spur at apex on mesal margin. Abdomen (Figs 3C, 23) with second-third ventrites impressed in middle third; third ventrite 0.60 wide, with lamina broad and thin, 0.23 wide, apex slightly and broadly emarginate on anterior margin, erect lamina arising just anterior to ventrite apex, strongly projecting and curved only near apex; fourth ventrite broadly impressed in middle two-fifths; fifth-sixth ventrites flattened in middle two-fifths, sixth ventrite (Fig. 3D) with oblique row of several thick setae to each side. Aedeagus (Fig. 3A) 0.34 long; left paramere broader than right, both with apices bluntly angulate; internal sac with armature, but form indistinct.

Females: Metatrochanter bluntly angulate on ventral margin near apex. Fifth tergite with setose area evenly convex; fifth ventrite (Fig. 3F) with margins of setose area parallel, apex with broad subrectangular tab at middle. Genitalia (Fig. 3E) with median lobe symmetrical, with 2 elongate curved rods in membranous lobe.

Collection notes.

During intensive sampling in 1981 and 1984 at the H.J. Andrews Experimental Forest in west-central Oregon, this species was taken most commonly in old growth Douglas-fir sites and from a 30 year-old clearcut regrowth, with only four specimens taken at sites cut more recently. In the Experimental Forest it has been found primarily in Douglas-fir leaf litter at low elevations. Most of the specimens were produced in the fall, winter, and spring, and seem to prefer drier sites. Most of this information is from unpublished data based on studies in the H.J. Andrews Experimental Forest by students of J. D. Lattin, and by the first author.

Geographical distribution.

(Map 1): This is the only species known from Oregon, and has been taken from forests at low to intermediate elevations on both sides of the Willamette Valley in west-central Oregon.

Comparisons and diagnostic notes.

Placed as a member of the arcaps-group, but the most distinctive member of the group. The male protibiae are angulate on the mesal margin and enlarged in the apical portion, the mesotibiae lack tubercles on the mesal margin, the metatrochanters have an acute spine on the mesal margin, the sixth ventrite has the setose area slightly constricted at the middle, and with short rows of thickened setae to each side of the midline. The female sixth ventrite has a broad tab on the apical margin, and there are two curved rods in the membranous lobe of the female genitalia. It is the only member of this group where the lamina of the third ventrite arises near the posterior margin and has the anterior margin shallowly concave.