Operclipygus diffluens, Caterino, Michael S. & Tishechkin, Alexey K., 2013

Caterino, Michael S. & Tishechkin, Alexey K., 2013, A systematic revision of Operclipygus Marseul (Coleoptera, Histeridae, Exosternini), ZooKeys 271, pp. 1-401 : 147-149

Operclipygus diffluens sp. n. Figs 39 A–B40A–D, IMap 15

Type locality.

ECUADOR: Orellana: Yasuní Research Station [0°40.5'S, 76°24'W].

Type material.

Holotype male: "Ecuador: Napo, mid.Rio Tiputini, Yasuní Res. Stn. 0°40.5'S, 76°24'W, FIT#2. 25-30 July 1999. AKT#108 A.Tishechkin" / "LSAM 0013287" / "Operclipygus sp. #16, Hist 137 Yasuní NP Inventory, A.K.Tishechkin det. 2010" (FMNH). Paratypes (3): same data as type, except as noted: 1: 17-23.vi.1999, FIT, C.E. Carlton & A.K. Tishechkin (LSAM); 1: 18-25.vii.1999, FIT, A.K. Tishechkin (LSAM); 1: 23-30.vi.1999, FIT, C.E. Carlton & A.K. Tishechkin (MSCC).

Other material.

COLOMBIA: Vaupés: 1: Est. Biol. Caparú, Rio Apoporis, 1.1°S, 69.5°W, 27. ix– 1.xii.1995, FIT, Black-water terrace forest on sandy soils, B.D. Gill (BDGC).

Diagnostic description.

Length: 1.44-1.75 mm, width: 1.25-1.47 mm; body rufobrunneus, elongate oval, moderately convex, widest behind humeri; frontal stria complete, more or less evenly rounded from sides to front; epistoma convex, shallowly emarginate at apex; labrum about half as long as wide, sides rounded, apex slightly asymmetrical, with left side produced more than right; left mandible with blunt basal tooth, right mandible with small subacute basal tooth; pronotum depressed across base; prescutellar impression short, linear, length about equal to that of scutellum; lateral submarginal pronotal stria complete, marginal bead relatively wide; anterior submarginal pronotal stria barely recurved at apices; pronotal disk with few, ~6, very faint coarse lateral punctures; elytra with outer subhumeral stria complete, inner subhumeral stria absent, striae 1-3 complete, striae 3-5 abruptly more broadly impressed at apices; prosternal carinal striae united very close to presternum; lateral metaventral stria extending obliquely toward posterior third of metepisternum, abbreviated at apex; 1st abdominal ventrite with two complete, subparallel lateral striae, disk lacking any median punctures; propygidium densely and uniformly convered with medium sized punctures; pygidium with fine dense ground punctation and slightly coarser punctures uniformly interspersed, separated by about 2 × their diameters; marginal pygidial sulcus finely but deeply impressed, weakly crenulate on edges. Male genitalia (Figs 40 A–D, I): accessory sclerites absent; T8 with sides convergent, basal apodemes rather short, basal emargination broad, shallow, nearly meeting basal membrane attachment line; S8 atypical for hospes group, sides subparallel, apical guides narrow, gradually widening to apex, ventral edges strongly divergent from base; 9T with sides subparallel in basal two-thirds, curving inward to narrow, subacute apices; T10 halves separate; S9 elongate, stem narrow for much of length, abruptly widened to rounded base; apex with narrow median emargination, apical flanges small, separate; tegmen widest about two-thirds from base, narrowed to rounded apex, medioventral process wide, rounded, projecting beneath near tegmen midpoint; basal piece about one-third tegmen length; median lobe about half tegmen length, filamentous portions of proximal apodemes short, inconspicuous.

Remarks.

This species and the four that follow are characterized by having the medioventral aedeagal process broadly rounded (Figs 40 I–L), neither acute nor truncate, and the tegmen lacking a subapicoventral cleft. None of these species have their 8th sternite broadly rounded at the base (Fig. 40B). Externally, most of the species have a complete outer subhumeral stria and expanded apices of elytral striae 2-4 (Fig. 39G). The last of these species, Operclipygus novateutoniae is an outlier in both of these respects, but its male genitalia associates it strongly with the other four.

The combination of apically expanded elytral striae (Fig. 39A), lack of coarse lateral pronotal punctures, dense propygidial punctation (Fig. 39B), and complete outer subhumeral elytral stria will distinguish Operclipygus diffluens from the following.

Etymology.

This species is named mainly as a counterpoint to the following, in which the 4th and 5th elytral striae are confluent apically. In Operclipygus diffluens they are separate. We restrict the type series to specimens from eastern Ecuador.