Idastes gibbosus (Montrouzier) Kuschel, 2008

Kuschel, Guillermo, 2008, Curculionoidea (weevils) of New Caledonia and Vanuatu: Basal families and some Curculionidae, Mémoires du Muséum national d'Histoire naturelle 197, pp. 99-250 : 216-217

Idastes gibbosus (Montrouzier) n. comb. (from Conotypus )

Fig. 103

Orobitis gibbosus Montrouzier, 1861a: 892 .

Conopsis gibbosus – Chevrolat 1877b: CXVIII.

Conopsis dispar Chevrolat, 1877 : CXVIII n. syn.

Idastes elevatus Pascoe, 1881: 599 n. syn.

DESCRIPTION. — Black, antennae and tarsi reddish brown. Scales large, unevenly distributed, leaving a good part of shiny integument exposed, most scales pale brown, sparse on a large triangle between shoulders and high point of elytra, denser behind bare triangle on interstrsiae 1-5 at first, then forming an ocker brown stripe on suture covering interstriae 1-3, yellow or ochrous on scutellum and on part of low elytral tubercles.

Head punctate, with brown scales, with two bare dots anteriorly. Forehead in male about as wide as rostrum in the middle, in female distinctly wider. Rostrum subcylindrical, gently curved, lacking carinae, in male distinctly punctate but punctation becoming gradually smaller apicad, sparsely squamose at base, in female much more finely punctate.

Prothorax conical or nearly so, with straight or gently convex sides; puncta distinct, spaced, with large, recumbent striolate scales. Scutellum yellowish, densely covered with small, erect, frayed scales.

Elytra conical, strongly compressed, bringing dorsum up to a distinct hump, separately rounded at apex, at shoulders considerably wider than prothorax, frequently with a fold running down obliquely from shoulder to interstria 10. Striae fine, intervals of strial puncta much greater than diameter of puncta; interstriae flat except for sutural one, interstria 3 with two low tubercles enhanced with dense, brown and yellow scales, 5 at apex with a hardly noticeable low tubercle; suture in male, just before apex beside end of sutural flanges, occasionally with a conspicuous spine, but mostly without such spine. A 5 abbreviated leaving anal cell open.

Rostral canal cavernous, with a pocket at end for reception of rostral apex. Metepisternum largely concealed except head and tail. Abdomen dull, nearly bare but scales a little denser on midline and sides. Tibiae with smooth line on upper and lower edges.

Male: tegmen with a fine, pigmented ring across dorsal surface, with short, broad, well-separated parameral lobes. Aedeagus (incl. apodemes) as long as last three ventrites combined, body relativcely short and broad, three-fifths length of apodemes, twice as long as wide, subparallel, apiculate, curved all the way except for short tip; pedon deeply pigmented, tectum distinctly pigmented but considerably paler, with a darker, tapering median area ending at ostium.

Female: tergite 7 as long as wide, converging from basal angle at spiracle to a rounded apex; punctation, pilosity and pale stripes containing plectral granules as in male; tertgite 8 more rapidly converging to end with three long, strong teeth. Sternite 8 a little longer than last three ventrites combined; blade a little longer than apodeme, with arms tapering, ending with a rather dark tip bearing two long setae and some apical and subapical hairs. Bursa extensively pigmented ventrally at base. Spermatheca with short cylindrical stem, with hook as thick as stem; gland sacciform, inserted halfway up stem, slightly longer than spermatheca; duct emerging from middle of base.

Length: 6.0-11.0 mm.

TYPE MATERIAL. — 1) Orobitis gibbosa : three syntypes present: lectotype female, 10.2 x 4.9 mm, ‘ Orobitis ? gibbosa (mihi), Balade, N. Cal.’ [in Montrouzier’s handwriting], type, Coll. Fauvel, IRSN. Paratypes with same data, at IRSN, MNHN. 2) Conopsis dispar : 2 syntypes specimens in IRSN. 3) Idastes elevatus : holotype male, 9.3 x 4.4 mm, ‘Aneiteum, Idastes elevatus Pasc. ’, NHML Identified non-type specimens with BPBM, IRSN, NHML, NZAC, QMBA.

MATERIAL EXAMINED. — New Caledonia. Balade, Bourail, Col d’Amieu, Col des Roussettes, Forêt de Thy, La Coulée, Mt. Koghi,

Mt. Rembai, Plateau de Dogny. 86 specimens.

HOSTPLANTS. — Tree-ferns of Cyathea (Krauss, Kuschel, Maddison) .

ETYMOLOGY. — The adjective ‘gibbósus’ refers to the hump induced by a strong compression of the elytra. REMARKS. — As there is no evidence that the genus Idastes occurs in Vanuatu, and errors of provenance of specimens occurred with some frequency in the times of sailing around the world, the record from Aneityum of I. gibbosus is best ignored. Males with a sutural spine are rare (15%), and presently known only from Bourail, Col des Roussettes, and Plateau de Dogny.