Trigonopterus nasutus (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 : 29-34

Trigonopterus nasutus (Pascoe)

Idotasia nasuta Pascoe, 1871: 261 . Type locality: Dorey [= Manokwari]

( Figs. 89–107 )

Diagnosis. Body ( Fig. 89 ) subovate, black. Eyes ( Fig. 90 ) large, medially approximate. Rostrum ( Figs. 90, 92 ) basally swollen, covered with white scales. Pronotum and elytra subglabrous, sparsely punctate; antecoxal projection of prothorax dentiform, directed ventrolaterad; male elytra with field of longitudinal striation. Metafemur subapically without stridulatory patch. Aedeagus ( Figs. 96–97, 100–101 ) with pointed apex.

Description. Lectotype, male ( Figs. 89–102 ). Length. Pronotum + elytra 3.20 mm.

Color black, except antennal scape and base of funicle deep ferruginous; dorsal surface of meso- and metafemur and basal half of rostrum with white scales, profemur with scattered white scales.

Habitus subrhomboid, with distinct constriction between prothorax and elytra; profile with constriction between pronotum and elytron. In thanatosis ( Fig. 95 ) legs sticking out from horizontal body plane at ca. 75°; dorsal edge of metafemur distant from elytral edge; femora overlapping tibiae; in lateral aspect gaps between legs fully closed, even at base.

Rostrum ( Figs. 90, 92 ) ca. 2.8 X as long as wide at base; in profile swollen in basal half, markedly curved ventrad, apical half straight; dorsal surface in basal half almost fully covered with white upcurved mesally directed scales, with indistinct median ridge and scabrous sculpture largely covered by vestiture; in apical half sparsely setose, laterally with regular rows of setae, sculpture shallow, weakly punctate, cuticle shining, weakly microreticulate; epistome simple, without tooth, posteriorly not delimited.

Head. Eyes ( Fig. 90 ) large, subovate, medially approximate, only partly concealed by pronotum when in thanatosis position; dorsal margin bordered by furrow on adjoining forehead. Forehead between eyes narrow, 0.6 X as wide as rostrum, foveate, vertex behind eyes smooth, with sparse minute punctures.

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

Pronotum 1.25 X wider than long, widest at base, sides weakly converging to middle, angulate, more distinctly converging in straight line to apex; without subapical constriction; anterior and posterior margins subtruncate; disc smooth, with minute punctures, becoming slightly larger towards sides, diameter still much smaller than interspaces between them; interspaces between punctures glabrous, polished; smoothly rounded towards sides; postocular lobe rounded, evenly continuous with straight profile of marginal carina; antecoxal projection of marginal carina conspicuous, dentiform, directed ventrolaterad; side above procoxa simple, without fovea; behind procoxa somewhat cavernous.

Elytra subovate, basally truncate, 1.25 X longer than wide, 1.23 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 thin hairline impressions and rows of small punctures; flat intervals subglabrous, polished; most basal puncture of striae 3-6 enlarged; stria 9 basally near humerus with 4 enlarged punctures laterally bordered by distinct costa, subapically engraved as furrow; in apical half laterally with field of distinct longitudinal striation; elytral apex simple, jointly evenly rounded, not extended ventrad.

Thoracic venter. Fig. 93 . Procoxa anteriorly squamose with white recumbent scales; mesal face flattened, subglabrous, with longitudinal furrow containing row of 6 scales. Ventral setose fringe of pronotal hypomeron forming distinct but relatively short receptacle brush; modified setae medially longer than lateral setae. Mesothoracic receptacle broadly U-shaped with short side-walls; ventrally produced beyond level of mesocoxal apex; weakly microreticulate, shining, sparsely punctate, with scattered small scales, posteriorly with pair of deep foveae containing three erect scales. Mesocoxa with mesal surface flattened, subglabrous; subapically with two blunt knobs, with sparse scales. Metaventrite medially shorter (0.8 X) than exposed part of mesoventrite, disc broadly concave, weakly microreticulate, with shallow punctures, with few transverse wrinkles; lateral intercoxal ridge markedly protruding ventrad, in lateral aspect triangular; in ventral aspect intercoxal ridge markedly oblique, 45° rotating mesad; edge hanging over anterior portion of metacoxa; anterior rim of metacoxal cavity with secondary denticle. Sides of metaventrite glabrous, bordered by costa except dorsally where even with epipleuron; intercoxal ridge punctate, sparsely squamose. Metacoxa in mesal angle with one suberect seta.

Legs. Femora markedly compressed laterally, shape subovate; tibial furrow of femora subglabrous, dull, largely pushed to posterior surface of femur, anterior surface widened. Anteroventral ridge distinct, bordered by row of scales and incomplete secondary ridge bearing tooth near middle of femur, all in front of bent tibia. Posteroventral ridge somewhat indistinct, simple. Anteroventral furrow deep, containing row of recumbent white scales. Pro-, meso- and metafemur of similar size, mesofemur smallest. Anteroventral contour of profemur convex, of meso- and metafemur straight. Anterior surface polished, punctate, profemur with some wrinkles and scattered white scales. Dorsal surface of meso- and metafemur densely clothed with recumbent white triangular scales, profemur with similar vestiture except basally with glabrous wedge. Posterior surface of profemur with two longitudinal ridges, especially basally coarsely punctate; posterior surface of mesa- and metafemur rather smooth, with two furrows containing rows of scales. Mesofemur with dorsal edge in basal third with angulation. Metafemur in repose passing elytral apex; dorsal margin convex; dorsoposterior edge sharp, without denticles; subapical posterior surface without stridulatory patch; suture with trochanter right-angled with ventral edge. Tibiae with fine longitudinal ridges bordered by rows of dorsad pointing setae; dorsal edges simple, without denticles; apex without premucro. Anterior setose comb of metatibia subapically following midline of metatibia from base of uncus. Tarsi with tarsomere 3 wide, bilobed, shape of apical lobes symmetrical; tarsomere 3 ca. 2 X as wide as tarsomere 2, slightly shorter (0.9 X) than tarsomere 2; claw-segment inserted in basal half of tarsomere 3; tarsomere 5 relatively long, 1.3 X as long as tarsomere 3; tarsal claws minute.

Abdomen. Ventrite 1 anterolaterally bordering metacoxa with dentiform protrusion, its outer surface supporting base of metafemur in thanatosis; posterolaterally in front of hind suture with densely punctate and sparsely squamose swelling. Ventrites 1 and 2 laterally densely deeply punctate, microreticulate, dull; medially forming common concavity, subglabrous, weakly microreticulate, weakly shining. Suture between ventrites 1-2 laterally distinct, medially effaced. Ventrites 3-4 narrow, of equal length, each with one indistinct row of shallow punctures. Ventrite 5 anteriorly at middle subglabrous, along lateral and apical margin densely punctate; surface relatively flat, at middle with shallow broad impression; apex crenulate.

Terminalia. Sternite VIII ( Figs. 98–99 ) subtrapezoid, apically with concave notch, sides markedly converging to apex, at base 1.7 X wider than long; laterally well-sclerotized, medially weakly sclerotized; apex laterally densely setose. Sternite IX ( Fig. 99 ) straight; apical arms forming “V”, their apical portions slightly widened, bent inward, half covered by sternite VIII. Tegmen ( Fig. 102 ) with complete, slender ring, apodeme relatively long, parameroid lobe indistinct, partly torn, apically without microchaetae. Aedeagus ( Figs. 96–97, 100–101 ); with sides of body slightly diverging, in apical 1/3 converging in straight line to pointed apex; sides more strongly sclerotized than dorsal and ventral surface; subglabrous; membrane of ostium transversely folded; with one pair of long endophallic sclerites from apical orifice reaching beyond basal orifice; apodemes ca. 2.3 X as long as aedeagal body; transfer apparatus relatively simple, swollen base of ductus ejaculatorius extended into short denticle; ductus ejaculatorius in lectotype broken and apical portion missing, at least as long as aedeagus, internally strongly sclerotized, basally near insertion with transfer apparatus relatively thick.

Female specimen. Same as holotype except: Length. Pronotum + elytra 2.8 mm. Rostrum in basal third swollen, with scabrous sculpture, covered with white upcurved scales; anterior 2/3 slender, subparallel, dorsally subglabrous, sparsely punctate, sides with pair of furrows containing rows of setae. Elytra in apical half laterally without longitudinal striation. Thoracic venter. Disc of metaventrite flat. Abdomen. Disc of ventrites 1-2 flat, anterior margin of ventrite 1 slightly projecting over metaventrite. Terminalia ( Figs. 103–107 ). Tergite VIII ( Fig. 107 ) as long as wide, spatulate, apical tip evenly rounded, simple, not crenulate. Sternite VIII ( Fig. 104 ) with apical plate subtrapezoid, medially with membranous area, apex concave, sublaterally setose. Coxite ( Fig. 105 ) subapically with one conspicuous seta, 2.0 X as long as stylus. Stylus ( Fig. 105 ) flattened, subapically widened, apically rounded and with dense, relatively short, stiff setae. Bursa copulatrix ( Fig. 103 ) without sclerites; ductus spermathecae markedly sclerotized throughout, at base widened and bilobate where entering bursa. Spermatheca ( Fig. 106 ) with lumen much reduced; apical 1/3 solid chitinous.

Intraspecific variation. Length, pronotum + elytron: males 2.75–3.20 mm (n=3, x =3.00 ± 0.23); females 2.65–2.88 mm (n=4, x =2.75 ± 0.11). Hairline impressions of elytral striae distinct, indistinct or completely absent. Material examined. Type specimens. Male, lectotype by present designation: INDONESIA, West Papua: Dorey [= Manokwari]; labels (fig. 94): 1) [blue, ovate] “Dorey [hand-written]” 2) [rectangular, white] “ Idotasia nasuta Pasc. , Type [hand-written]” 3) [rectangular, white] “Pascoe Coll. B.M.1893-60 [printed]” 4) [rectangular, white] “Pascoe Coll. B.M.1893-60 [printed]” 5) [round, white with blue margin] “ SYNTYPE [printed]” 6) [rectangular, red] “ LECTOTYPE, Idotasia nasuta Pascoe , det A.Riedel 2007 [printed]” (BMNH).

Other specimens. INDONESIA, West Papua, Manokwari reg.: 1 male, 1 female, Manokwari, Gn. Meja, ca. 300m, 22-23.IX.1990, leg. A. Riedel (ARC); 1 female, Manokwari, Gn. Meja, ca. 200m, 21-24.VIII.1991, leg. A. Riedel (ARC); 1 female, Manokwari, Gn. Meja, ca. 200m, 30.XII.2000 - 1.I.2001, leg. A. Riedel (ARC); 1 male, ARC391, EMBL Accession# HE565597 , Manokwari, Gn. Meja, S 01°51.11´, E 134°04.37´, 200m, 01.III.2007, leg. A. Weigel (SMNK); 1 female, Ransiki, Mayuby, ca. 300m, 26-30.IX.1990, leg. A. Riedel (ARC).

Distribution. INDONESIA, West Papua (Manokwari).

Notes. Pascoe (1871) did not designate a holotype in the original description but quotes specimens from three localities (“Dorey, Morty, Waigiou”). Three syntypes stored at the BMNH could be examined: a male from “Dorey” and a female from “Waigiou” belong to different species. The female from “Morty” may belong to the same species as the syntype from “Dorey”, but even this assignment is uncertain. The male syntype from “Dorey” is here designated lectotype to ensure stability of nomenclature. Two additional specimens mentioned by Pascoe (1885) as “ I. nasuta ” from Fly River were also examined; one of them belongs to T. ampliatus (Pascoe) , the other probably belongs to a species similar to but distinct from T. nasutus . Thus, the record “Fly River” for T. nasutus should be deleted.

Figures

FIGURES 89 – 95. Trigonopterus nasutus, lectotype: (89) dorsal aspect; (90) frontal aspect; (91) dorsal aspect; (92) lateral aspect; (93) ventral aspect; (94) labels; (95) thanatosis position, lateral aspect.

FIGURES 96 – 102. Male terminalia of Trigonopterus nasutus, lectotype: (96, 100) aedeagus, lateral aspect; (97, 101) aedeagus, dorsal aspect; (102) tegmen; (98 – 99) sternite VIII – IX.

FIGURES 103 – 107. Female terminalia of Trigonopterus nasutus, Manokwari: (103) overview; (104) sternite VIII; (105) coxite; (106) spermatheca; (107) tergite VIII.