Prionocerus opacipennis (Pic, 1920) Pic, 1920

Geiser, Michael, 2010, Studies on Prionoceridae (Coleoptera: Cleroidea). II. A revision of the genus Prionocerus Perty, 1831, Zootaxa 2328, pp. 1-48 : 37-39

Prionocerus opacipennis (Pic, 1920) n. comb.

Idgia opacipennis Pic, 1920a: 7 .

Type material examined: Holotype 3: "Mentawei, Sipora"; "Pr. caeruleipennis var. (désiré)"; " type "; " TYPE "; " opacipennis Pic "; MNHP, in good condition.

Other material examined: INDONESIA: SUMATRA: "Sumatra, Pajacumbo" 1 3 1 Ƥ ( MNHP), 1 Ƥ ( NHMB). MENTAWAI: "Sipora, Sereina, V.-VI. 94, Modigliani" 1 3 ( MCGD). THAILAND: Saraburi, XI. 1988, Sab. Steinke leg. 1 3 ( SMNS).

Measurements 3 (n = 4): TBL 11.2–13.3 mm, L-h 9.4–11.3 mm

HL 1.8–2.0 mm, PL 1.9–2.2 mm, EL 7.5–9.1 mm

Measurements Ƥ (n = 1, as one specimen lacks its head): TBL 12.6 mm, L-h 10.7 mm

HL 1.9 mm, PL 2.1 mm, EL 8.6 mm

Differential diagnosis: Habitus as in fig. 41 (3). Distinguished from all other Prionocerus by the pronotal shape (more slender and elongate), larger and more massive antennae, and in males by the shape of the aedeagus and the last abdominal sternite.

Redescription: Body metallic bluish green, head and scutellum slightly darker blue. Pronotum bright reddish orange. Elytra dark blue or dark green. Central part of antennae dark brown, basal three segments partly lighter reddish brown, the apical part of antennae to a variable extent light yellowish brown (at least the last segment and parts of segments 9–10). Maxillary and labial palpi, maxillae and outer edge of labrum and clypeus light reddish to yellowish brown. Legs dark metallic blue, tarsi almost black, claws reddish brown.

Head about as wide or very slightly wider than half of the pronotum, similar in shape to P. coeruleipennis . Vertex shining, very sparsely and very finely punctate and with some erect black setae. Frons between eyes shining, sparsely punctate, narrower than half the length of the first antennal joint in males, almost as broad in females; in front of the eyes distinctly depressed and slightly rugose. Clypeus almost trapezoidal, wider than long and slightly convex, with a few coarse punctures bearing black setae. Labrum about as long as wide, flat and more coarsely punctate than the head (except clypeus), with some moderately long blackish hairs.

Male antennae surpassing the first third of the elytra in length, longer than in any of the related species. First three segments subfiliform, segments 4–5 slightly widened and flattened, 6–10 of subtriangular shape, very strongly flattened and widened. Last segment robust, not conspicuously widened, large and strongly emarginate. First segment long, second very short, only about third as long, third segment again long, almost like the first, the following segments gradually decreasing in length and increasing in width, the last segment longest, slightly longer than the first. Female antennae very much shorter, hardly reaching the shoulders of the elytra; all segments much smaller than in males, but of similar shape; second segment about half as long as the first; third longest; last one slightly shorter than the first.

Pronotum slightly longer than wide, maximal length: maximal width 1: 0.92–1: 0.98, subhexagonal, widest part in front half, before the middle, all angles rounded, basal angles of about 90°; with two shallow, sometimes very vague, oblique impressions in the basal half, at both sides of the disc, slightly convex near hind angles and in the middle of the disc; finely bordered, the bordering becoming very vague in the middle of the front margin; shining, sparsely covered with shallow punctures and black (or sometimes golden yellow) short, suberect hairs; lateral margins with some slightly longer black hair-like setae.

Elytra about 2.7 times as long as wide in males, about 2.6 times in females, of subparallel shape, widest in apical half; humeral area convex, apical half less flattened than in other species; finely and very densely punctate over the whole surface, rugose in all parts except basal area, punctures getting shallower towards the apex; pubescence sparse, pale and hardly visible, with very small, short, recumbent hairs; with few longer black, erect hairs, that are usually only visible in profile; no granular rows visible within the dense puncture. Margins finely, regularly crenulate, the crenules all bearing blackish setae intermixed with smaller brownish hairs. Scutellum narrower than in P. coeruleipennis , about as wide as long, with very fine punctures and sparse brownish pubescence.

Femora ant tibiae slightly metallic, covered with fine punctures, greyish, recumbent pubescence and black or brownish setae. Tarsi not metallic, with blackish setae and some greyish, recumbent hairs.

Abdomen with rather long, but usually not very dense, greyish, recumbent pubescence and some longer black, suberect setae; with rather sparse, shallow punctures and somewhat rugose texture on some parts.

Male: Last abdominal sternite very large and massive, similar in shape to P. championi , but broader (fig. 28). Basal margin arcuate. Apical margin very deeply incised in the middle, the under edge of the incision of semicircular shape, the opening very large and of subtriangular shape. Last tergite not emarginate.

Aedeagus (figs. 6, 13, 20): Process of phallobase pointing backwards, but standing in an angle of more than 60° to the parameral apex, as the phallobase is strongly curved. Paramera not straight, slightly arcuate, narrowed to about the middle, then apical area slightly thickened, but not as much as in P. championi ; apical part with a row of minute, black teeth along its ventral edge, but no dorsal tooth visible; ventral edge of subapical part (not the extreme tip) with several long, brownish hairs. Seen in dorsal view, the paramera are largely gaping and slightly curved, similar to P. championi , but a bit broader. Median lobe rather robust, with its basal part strongly curved, then not straight but clearly sinuate in middle and apical part, apex more gradually flattened, without dorsal hook, the extreme tip flat and pointing ventrally. In dorsal view with elongate, subparallel ostium; after the ostium only slightly and more gradually narrowed with bluntly rounded and a fine central furrow.

Sexual dimorphism: The single undamaged female assigned to this species has about the same body size and shape as the males, but much shorter and less massive antennae. It shows the usual dimorphism in size of the eyes and the frons between them.

Variability: The colour of the elytra can vary from dark blue (holotype) over dark green with blue humeral area (specimens from Sumatra) to uniformously dark green metallic ( Thailand). The specimen from Thailand has the last antennal segment of slightly different size, with slightly shorter, less produced apex.

Distribution (fig. 45): Known from the Mentawei Islands and Sumatra in Indonesia, as well as from Central Thailand. It is probable that the large geographic gap between this localities may be closed by further collecting efforts.