Operclipygus geometricus (Casey, 1893) Casey, 1893

Caterino, Michael S. & Tishechkin, Alexey K., 2013, A systematic revision of Operclipygus Marseul (Coleoptera, Histeridae, Exosternini), ZooKeys 271, pp. 1-401 : 210-212

Operclipygus geometricus (Casey, 1893) comb. n. Figs 57J58AMap 20

Phelister geometricus Casey, 1893: 550.

Type locality.

Not specified beyond Texas State, USA.

Type material.

Holotype: “Tex” / "geometricus Csy" / "CASEY bequest 1925" / "TYPE USNM 38456" (USNM), examined 2011.

Other material.

MEXICO: Hidalgo: 1: 5.v.1939, HSB (TAMU); USA: Oklahoma: 1: Latimer Co., iv.1994, K. Stephan (TAMU), 1: ix.1990, K. Stephan (TAMU), 1: v.1988, K. Stephan (TAMU), 1: vi.1995, K. Stephan (TAMU), 1: vii.1995, K. Stephan (TAMU); USA: Texas: 17: Fort Bend Co., Brazos Bend St. Pk., 15. vi– 23.ix.2000, FIT, buckeye-sycamore forest, B. Raber & E. Riley (TAMU, FMNH, MSCC, AKTC), 24: 4. vi– 25.ix.2000 (TAMU).

Diagnostic description.

Length: 1.90-2.15 mm, width: 1.56-1.84 mm; body rufobrunneus, slightly elongate oval, widest behind humeri, moderately convex; frons depressed at middle, sides of frontal stria weakly divergent, frequently interrupted over antennal bases, central part sinuate, weakly crenulate; supraorbital stria weak, fragmented to complete; labrum slightly asymmetrically emarginate apically; left mandible without tooth, right mandible with small acute basal tooth; prescutellar impression absent; pronotal disk wth fine sparse ground punctation and numerous (~20) coarse elongate punctures laterally; marginal pronotal stria fine, complete around sides and front; lateral submarginal stria close to margin at sides, frequently fragmented toward base, curving inward at front nearly to anterior submarginal stria, which is barely recurved posterad at sides; median pronotal gland openings far behind ends of anterior stria, three-fourths of the distance from the anterior to the posterior pronotal margin; elytra with two complete epipleural striae, the uppermost broadly sulciform, outer subhumeral stria represented by only short apical fragment, rarely with short basal fragment also, inner subhumeral stria absent, striae 1-4 complete, the 4th stria arched inward basally, ending freely, 5th stria present in apical half to two-thirds, sutural stria slightly shorter; elytral disk with few small punctures subserially arranged along apical margin; prosternal keel weakly emarginate at base, carinal striae complete, rather widely separated to front, united in broad anterior arch; prosternal lobe with weak, frequently fragmented marginal stria; anterior mesoventral margin weakly projecting, marginal stria weak, generally interrupted at middle; mesometaventral stria arched strongly forward to near anterior mesoventral margin, forming a continuous arc with lateral metaventral stria which extends posterad to inner third of metacoxa; 1st abdominal ventrite with single, incomplete lateral stria, punctures of lateral part of disk coalescing into elongate strigosity posterolaterad coxa; propygidium uniformly covered with shallow, round punctures separated by about one-half their diameters, lacking microsculpture; pygidium with ground punctation fine, sparse, with small punctures throughout, separated by about twice their diameters; marginal pygidial stria finely impressed along apical half of margin, weak and rarely fragmented. Male genitalia with segments 8-10 identical to those of Operclipygus hamistrius (see Figs 57 A–D); tegmen (Fig. 57J) shorter, narrower, especially toward apex, widest in basal half, strongly bent ventrally in apical third, medioventral process small, projecting beneath about, one-fourth from base.

Remarks. While the distribution of this species is practically diagnostic, it differs substantially from other members of the group in several characters. The frontal stria is frequently complete, or narrowly interrupted over the antennae; the elytral striae are strongly and crenulately impressed (Fig. 58A), with the outer subhumeral stria very short and apical; it is essentially devoid of microsculpture, except rarely on the sides of the sterna; and the propygidial punctures are unusually dense and numerous. With its broken submarginal pronotal striae and displaced median pronotal gland openings it cannot be confused with any other Exosternini in or near the Nearctic.