Trigonopterus ebriosus (Pascoe)

Riedel, Alexander, 2011, The weevil genus Trigonopterus Fauvel (Coleoptera, Curculionidae) and its synonyms — a taxonomic study on the species tied to its genus-group names, Zootaxa 2977, pp. 1-49 : 3-7

Trigonopterus ebriosus (Pascoe)

Idotasia ebriosa Pascoe, 1871: 261 .

( Figs. 1–13 )

Diagnosis. Body ( Fig. 1 ) subrhomboid, black, polished, densely punctate. Base of rostrum ( Fig. 3 ) with marked dorsal protrusion, covered with silvery upcurved scales; sides with deep secondary scrobe. Disc of pronotum densely punctate with ovate punctures. Metafemur dorsally covered with white scales, subapically with stridulatory patch. Aedeagus ( Figs. 7–8, 11–12 ) apically with deep median ellipsoid incision; transfer apparatus simple, spearshaped.

Description. Lectotype, male ( Figs. 1–13 ). Length. Pronotum + elytra 2.3 mm.

Color black, antenna and tarsi ferruginous. Integument of elytra and pronotum polished, punctate, nude except punctures containing each one minute seta; legs with scattered inconspicuous white recumbent scales; dorsal edge of meso- and metafemur covered with recumbent silvery-grey scales; base of rostrum covered with upcurved silvery-grey scales.

Habitus subovate to subrhomboid, almost without constriction between prothorax and elytra; body in profile dorsally evenly convex. In thanatosis ( Fig. 6 ) legs forming compact unit, sticking out from horizontal body plane at ca. 70°; dorsal edge of metafemur distant from elytral edge; femora partly overlapping tibiae, partly left exposed; gaps between legs distinct, especially at base.

Rostrum ( Figs. 2–3 ) ca. 2.0 X as long as wide at base, markedly curved ventrad; at base with marked dorsal protrusion; in profile dorsal protrusion convex, in apical half contours of rostrum converging in straight line; dorsally foveate, with distinct median ridge; basal protrusion with silvery-grey upcurved scales directed mesally, almost concealing the cuticle; laterally with deep secondary scrobe curving from above eye parallel to and above antennal scrobes to apical third of rostrum, deeply undercutting median dorsal protrusion; anterior quarter flattened, median costa disappearing, subglabrous, punctures shallow, with sparse suberect setae; epistome simple, without tooth; in thanatosis, swollen basal portion projecting beyond marginal carina of rostral canal.

Head. Eye subovate, largely concealed by pronotum when in thanatosis position; dorsal margin bordered by distinct furrow. Forehead between eyes narrower than rostral base (0.7 X), densely punctate; vertex behind eyes subglabrous, with sparse minute punctures.

Antenna inserted somewhat behind middle of rostrum. Scape short, subequal to article 1 + 2 of funicle, fully concealed in rostral channel in thanatosis position. Left antenna missing.

Pronotum 1.60 X wider than long, widest at base, sides converging in straight line to apex, only laterally with traces of weak subapical constriction; anterior margin bisinuate, posterior margin straight; disc densely punctate with ovate punctures, narrow midline impunctate; along submedian line with 14 punctures; interspaces subequal to puncture´s diameter, glabrous; smoothly rounded towards sides; postocular lobe subangulate, continuous with slightly concave profile of marginal carina, antecoxal projection of marginal carina distinct, subacute, directed ventrad; side above procoxa simple, without fovea.

Elytra pyriform, basally truncate, apically slightly extended, 1.26 X longer than wide, 1.25 X wider than base of pronotum, widest in basal 0.28 of elytral length; profile dorsally smoothly convex, 0.66 X as deep as long; striae marked by row of small punctures; flat intervals with row of similar punctures, resulting in confused punctation, subapically punctures confluent, partly rugose; interspaces flat, glabrous, polished; punctures of transverse row bordering basal margin somewhat larger than elytral punctures behind; striae 8 and 9 indistinct, especially near humerus, intervals without any ridge; subapically stria 9 deeply entrenched, furrow containing dense row of punctures; suture at elytral apex weakly incised, elytra individually rounded.

Thoracic venter. Fig. 4 . Procoxa anteriorly punctate, posteroapically with tooth and sparse cluster of erect scales, mesal face subglabrous, at middle with row of 4 pits. Ventral setose fringe of pronotal hypomeron forming distinct receptacle brush; modified setae medially distinctly longer than lateral setae. Mesothoracic receptacle broadly U-shaped with short side-walls; ventrally produced to level of mesocoxal apex; posteriorly subglabrous, microreticulate, dull, with pair of deep foveae, ventral rim of side walls with white scales. Mesocoxa with scattered suberect scales, posteriorly with two teeth. Metaventrite medially 1.2 X longer than exposed part of mesoventrite, disc broadly concave, subglabrous; lateral intercoxal ridge markedly protruding ventrad, in lateral aspect triangular, in ventral aspect intercoxal ridge oblique, its anterior end rotating distinctly mesad; posteriorly intercoxal ridge weakly extending over metacoxa; anterior rim of metacoxal cavity without secondary denticle. Sides of metaventrite glabrous, bordered by costa except dorsally where even with epipleuron; intercoxal ridge coriaceous. Metacoxa in mesal angle with long, erect, mesoposteriad directed setae.

Legs. Femora relatively long, moderately compressed laterally; with distinct but simple anteroventral ridge overlapping bent tibia; posteroventral ridge less marked but still distinct; without ventral teeth; anteroventral furrow distinct, bordered by fringe of narrow scales. Pro-, meso- and metafemur of similar size, elongate, sides subparallel, subapically weakly bent ventrad. Profemur anteriorly polished, punctate; posteriorly longitudinally strigulate, densely coarsely punctate; punctures containing inconspicuous scales; dorsally simple, without scaling. Mesofemur similar to profemur, but dorsoposterior edge bordered by row of white scales and indistinct row of denticles; posterior surface polished, sparsely punctate. Metafemur in repose passing elytral apex, similar to pro- and mesofemur; anterior surface weakly strigulate, punctate; posterior surface largely polished, with row of deep punctures; subapical posterior surface with distinct stridulatory patch of transverse striation; basal limits of stridulatory patch ill-defined; dorsoposterior edge with distinct row of 5 denticles, dorsal surface covered with white upcurved to subrecumbent scales; suture with trochanter right-angled with ventral edge. Tibiae with fine longitudinal ridges bordered by rows of dorsad pointing scales; dorsal edge of protibia simple, meso- and metatibia with row of denticles; apex with uncus and with smaller premucro. Anterior setose comb of metatibia subapically following midline of metatibia from base of uncus; in anterior quarter metatibia narrowed, dorsally with row of erect white scales. Tarsi with tarsomere 3 subtrapezoid, anteriorly markedly widened, shape of apical lobes symmetrical; tarsomere 3 ca. 1.6 X as wide as tarsomere 2, 1.3 X longer than tarsomere 2; claw-segment inserted at center of tarsomere 3; tarsomere 5 as long as tarsomere 3; tarsal claws minute.

Abdomen. Ventrite 1 anteriorly flat, dull, laterally behind metacoxae with longitudinal wrinkle. Ventrites 1 and 2 forming common subglabrous concavity; suture between ventrites 1-2 distinct throughout. Ventrites 3-4 narrow, of equal length, subglabrous, each with one transverse row of sparse minute punctures. Ventrite 5 filled with bowlshaped impression laterally defined by pair of ridges, anteriorly and posteriorly open; bottom of impression subglabrous; ridges dull, inner edge with row of erect scales; apex simple, not crenulate.

Terminalia. Sternite VIII ( Figs. 9–10 ) subtrapezoid, sides weakly converging to subtruncate apex, at base 2.2 X wider than long; lateral edges well-sclerotized, disc weakly sclerotized; apex laterally setose. Sternite IX ( Fig. 10 ) straight, apical arms forming “V”, apical half where covered by sternite VIII subparallel. Tegmen ( Fig. 13 ) with complete, slender ring [broken in lectotype], apodeme relatively long, parameroid lobes missing. Aedeagus ( Figs. 7–8, 11–12 ); body with sides weakly convex, apex with deep median ellipsoid incision; dorsal surface sublaterally with rows of sparse long setae; membrane of ostium transversely folded, projecting over apical incision; with two pairs of long endophallic sclerites; apodemes ca. 2.0 X as long as aedeagal body; transfer apparatus simple, spearshaped, mainly contained in endophallus, its apex reaching base of aedeagal body; ductus ejaculatorius internally strongly sclerotized, apical portion broken and missing.

Material examined. Type specimens. Male, lectotype by present designation: INDONESIA, West Papua: Salawatti Isl.; labels ( Fig. 5 ): 1) [blue, ovate] “Salawatty [hand-written]” 2) [rectangular, white] “ Idotasia ebriosa Pasc. , Type [hand-written]” 3) [rectangular, white with black margin] “ Idotasia ebriosa Pasc. [hand-written]” 4) [rectangular, white] “Pascoe Coll. B.M.1893-60 [printed]” 5) [round, white with red margin] “ HOLOTYPE [printed]” 6) [rectangular, red] “ LECTOTYPE, Idotasia ebriosa Pascoe , det A.Riedel 2009 [printed]” condition: fair; specimen originally card-mounted, remounted on point; genitalia in glycerol in microtube ( BMNH).

Distribution. INDONESIA, West Papua (Salawatti Isl.).

Notes. Pascoe (1871) did not designate a holotype in the original description nor specified the number of specimens examined. The round label stating “ Holotype ”, has subsequently been added by the staff of the BMNH. Other specimens may exist in addition to the specimen stored at the BMNH, which is considered a syntype and is here designated lectotype to ensure stability of nomenclature in case additional syntypes are discovered that belong to different species.

As indicated by the peculiar structure of the aedeagus with a deep median incision and the swollen rostral base this species is closely related to T. inclusus (Pascoe) from Misool Island. It can be separated by the sculpture of the pronotum consisting of separate, non-rugose punctures and by the absence of an endophallic sclerite guiding the flagellum.

Figures

FIGURES 1 – 6. Trigonopterus ebriosus, lectotype: (1) dorsal aspect; (2) frontal aspect; (3) lateral aspect; (4) ventral aspect; (5) labels; (6) thanatosis position, lateral aspect.

FIGURES 7 – 13. Male terminalia of Trigonopterus ebriosus, lectotype: (7, 11) aedeagus, lateral aspect; (8, 12) aedeagus, dorsal aspect; (9 – 10) sternite VIII – IX; (13) tegmen.