Operclipygus siluriformis, 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 : 353-356

Operclipygus siluriformis sp. n. Figs 99 A–EMap 34

Type locality.

BRAZIL: Mato Grosso:Fazenda São Nicolau [9°50.3'S, 58°15.05'W].

Type material.

Holotype male: "BRASIL: Mato Grosso: Mpio Cotriguaçu, Fazenda São Nicolau, Matinha. 9°50.3'S, 58°15.05'W. Flight intercept Oct 2009. F.Z.Vaz-de-Mello" / "Caterino/Tishechkin Exosternini Voucher EXO-00985" (CEMT). Paratypes (10): 10: same data as type, except as noted: 4: xii.2010 (CEMT, FMNH, UFPR, MSCC, AKTC); 3: Cotriguaçu, Fazenda São Nicolau, Prainha, 9°51.6'S, 58°12.9'W, x.2009 (FMNH); 3: Cotriguaçu, Fazenda São Nicolau, Mata Norte, 9°49.15'S, 58°15.6'W, 8-14.xii.2010, FIT, F.Z. Vaz-de-Mello (MSCC, AKTC).

Other material. BRAZIL: Pará: 2: IPEAN, Utinga, Belém, 1°27'S, 48°26'W, viii.1985, FIT (CHND), 5: x.1984, FIT (CHND), 1: xi.1984, FIT (CHND), 1: x.1985, FIT (CHND); 1: Belém, 1°3.1'S, 48°8.8'W, 27.vii.1984 (CHND); 9: Carajás, Serra Norte, 6°04'S, 50°12'W, xi.1984, FIT (CHND); 1: Altamira - Marabá: km 18., 3°09'S, 52°03'W, 10-23.ix.1985, FIT (CHND); 1: Barcarena, 1°30'S, 48°37'W, 19 -30.ix.1991, FIT (CHND); 1: Melgaço, Rio Marinaú, 1°51'S, 51°20'W, 31. x– 13.xi.1993, FIT (CHND); 7: Tucuruí, 3°45'S, 49°40'W, 6-17.vi.1986, FIT (CHND). PERU: Junín: 1: 11km NE Puerto Ocopa, Los Olivos, 11°7.00'S, 74°15.52'W, 1200m, 30-31.iii.2009, Window trap, A.V. Petrov (AKTC).

Diagnostic description.

Length: 2.22-2.50 mm, width: 1.87-2.03 mm; body rufo-brunneus, elongate, nearly parallel-sided, sides of elytra weakly arcuate; frons moderately depressed behind frontal stria; frontal stria with sides divergent between eyes, sinuate above antennal bases, continuous, arcuate across front; supraorbital stria complete, meeting sides of frontal stria, area enclosed by frontal and supraorbital striae rather short; labrum about twice as wide as long, rather flat, apical margin shallowly emarginate; left mandible with short, blunt basal tooth, right mandible with more pronounced, subacute tooth; prothorax with disk vaguely and weakly impressed in prescutellar region, very fine, sparse ground punctation, relatively narrow band of ~10 punctures mediad lateral submarginal stria; marginal pronotal stria absent along most of anterior pronotal margin, complete lateral submarginal stria replacing it for a short distance at sides; marginal pronotal bead strongly convex, widening slightly toward the front; anterior submarginal stria weakly recurved posterad at sides; median pronotal gland openings anterolaterad ends of anterior submarginal stria, about three puncture widths from anterior margin; elytra with one complete epipleural stria, outer subhumeral stria complete, inner subhumeral stria absent, striae 1-4 complete, 5th stria present in apical third, sutural stria present in apical three-fourths, the sutural stria broadening toward base; prosternal keel with base rounded, produced strongly into mesoventrite, carinal striae complete, convergent from base, parallel in anterior half, united by narrow arch; prosternal lobe with complete marginal stria; mesoventral margin emarginate, with marginal stria interrupted; mesometaventral stria arched forward to anterior third of mesoventral disk, continued by lateral metaventral stria posterad toward middle of metacoxa; lateral part of metaventral disk with oblique secondary lateral stria; 1st abdominal ventrite with two complete lateral striae, parallel throughout their lengths; propygidium with fine, dense ground punctation at sides, in middle with slightly elongate, rather deep punctures separated by less than half their diameters, larger punctures also present along entire anterior and lateral margins of propygidium; pygidium with ground punctation as on sides of propygidium, with some larger punctures sparsely interspersed; marginal pygidial sulcus deep, complete, crenulate on inner and outer edges. Male: accessory sclerites absent; T8 with sides convergent from base to apex, apices truncate, apical emargination narrow, basal emargination shallow, nearly reaching basal membrane attachment line, ventrolateral apodemes most strongly developed near base, divergent to apex; S8 with sides with sides slightly divergent, apical guides narrow, gradually widened to apex, ventral halves approximate in basal half, divergent apically; T9 parallel-sided in basal two-thirds, convergent to apex, apices widened inward, apically truncate; T10 weakly sclerotized along midline, margins indistinct; S9 stem fairly wide, narrowest near apex, widened to broadly rounded base, with distinct apical emargination, apical flanges small and separate; tegmen stout, widest at middle, evenly narrowed to base and apex, apices broad, appearing truncate from above, with membraneous ventrolateral processes extending from apical corners; medioventral process not at all evident; basal piece almost half tegmen length; median lobe over half tegmen length, with wide gonopore, proximal apodemes strongly differentiated into short, broad, separated bases, and long, well sclerotized extensions reaching to base of tegmen.

Remarks.

This species and the following, Operclipygus parallelus , are very similar and distinctive externally, both being relatively elongate (Fig. 98D), having a complete outer subhumeral stria, and a propygidium with fine dense punctures on either side of a more coarsely punctate central area (Fig. 98E). This type of propygidum can be found in a few other species, but these species are larger and more distinctly parallel-sided than any others. Their genitalia (Fig. 99) are remarkably different given their external similarity, but they do share a few important characters, and appear to be related: they lack accessory sclerites at the base of T8; apices of T9 are widened and appearing obliquely truncate; the inner edges of T10 are desclerotized and separate; apex of S9 emarginate, with separate apical flanges; median lobe relatively short, but with a large gonopore and elongate basal apodemes with strongly sclerotized basal stems. The tegmen of the Operclipygus siluriformis is remarkable (Fig. 99E), with a broad truncate apex bearing whisker-like apical processes, which do not appear to be setae. It lacks an articulated medioventral process, although the tegmen itself has a basoventral cusp. Externally very few characters separate Operclipygus siluriformis and Operclipygus parallelus . The body of Operclipygus siluriformis is slightly more rounded at the sides, the marginal bead of the pronotum is more distinctly and strongly widened to the front, the sides of the metaventral disk are less strongly rugose, it lacks a basal puncture at the 5th dorsal stria, and the labrum is always weakly emarginate, rather than outwardly rounded. Similar apical aedeagal processes are also seen in Operclipygus punctipleurus , but that species shares few other characters, and does not appear to be closely related.

We restrict this type series to specimens from the same locality as the holotype. Considerable variation throughout the range, in combination with the existence of an extremely similar, partially sympatric species urges conservatism. At the same time it is worth noting that individuals from Para, Brazil, and even the geographical outlier from Peru, were dissected to confirm the presence of the highly distinctive aedeagus.

Etymology.

The name is derived from the catfish suborder Siluriformes , and refers to the whisker-like appendages at the apex of the aedeagus.