Strabonus, 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 : 184-186

Genus STRABONUS n. gen.

Type species: Rhynchites kanalensis Perroud.

DESCRIPTION. — A genus comprising several species from New Caledonia characterised by having a stout, deep body, a usually straight rostrum, large, dorsally approximated eyes, elytra considerably broader than prothorax, less than half as long again as combined width, ventrites on sides strongly curved backwards, tibiae carinate and sulcate on dorsal edge, claws divaricate, laminate at base, lack of stridulatory files in both sexes, and in male tergite 8 partly exposed as a small pygidium.

Head behind eyes exposed to a good extent, not constricted, weakly sculptured. Eyes large, laterodorsal, narrowly separate on frons, round or slightly elongate-oval, moderately convex in relation to head capsule, coarsely facetted. Rostrum straight or slightly curved, shorter than prothorax; postrostrum usually deep, tectiform in male, less deep, distinctly depressed in female, usually with a row of coalescent puncta forming a sulcus alongside scrobes; prerostrum shorter and a little wider than postrostrum; epistome with shallow emargination. Antennae antemedian; scape extending to or passing front margin of eyes, usuallycurved outward, compressed especially in male; funicle 7-segmented, first two segments subequal in length, others much shorter; club long, about thrice as long as wide, segments well defined, terminal one with a slight constriction.

Prothorax as long as wide or slightly transverse, not or hardly rounded on sides, roundedly protruding at apex, truncate at base, with very weak dorsal constriction at apex, with weak rim at base. Scutellum flat, rounded at apex, falling vertically at base.

Elytra at shoulders considerably wider than prothorax, distinctly less than half as long again as combined width, usually widened towards middle, weakly convex across basal area, strongly convex across middle, in lateral view deep, strongly convex, somewhat humped; basal fall vertical, with a well marked impression from pressing against prothorax. Striae distinct 10, the10th usually appearing in part as a finely engraved line from alongside metepisternal apex to end of ventrite 4. Left sutural flange considerably wider than right flange; inferolateral flange distinct; inferolateral carina or line weak, abbreviated; stridulatory files absent, occasionally with a strongly convex interstria 9 at apex flanked behind by a fine, sharp carina. Wing venation approaching that of Ixalma ( Zherikhin & Gratshev 1995, fig. 159) but stigmatical area larger, more intensely pigmented, with a narrow, anteriorly closed window.

Prosternurn very short, at most as long as area behind coxae, without indication of a fold or rostral canal. Mesosternal process oblique, with abundant pilosity. Metasternum moderately convex between middle and hind coxae; metepisternal suture distinct, lacking sclerolepidia. Fore coxae contiguous. Legs long; hind femora usually extending to end of abdomen or beyond; femora with [or without] tooth. Tibiae straight on dorsal edge, well sculptured, carinulate and sulcate at dorsal edge; fore and middle tibiae with conspicuous uncus, hind tibiae with an uncus-mucro, but more commonly lower edge extended to a point or narrow lamina. Segment 3 of tarsi broadly bilobed; claw segment short, passing only moderately beyond pads of segment 3; claws divaricate, laminate at base.

Abdomen weakly convex in male, strongly in female; first two ventrites fused, usually with partly obliterated suture, combined length behind coxal cavity equalling length of ventrite 5; segments 2-4 with backwards curved hind angles (Fig. 127), last segment as long as 3 + 4, usually bisinuous at apex (Fig.127), in female rather strongly curved upwards below elytra. Tergites faintly to intensely pigmented, with a broad paler stripe along midline; tergites 4-7 with pruinose areas; tergite 7 darker, in male concavely arched at apex, in female broadly rounded at apex (Fig.123), in both sexes punctate at least on distal half, usually with a short, rigid, spinule-like seta in each punctum.

Male: tergite 8 (Figs 128, 129) well-exposed beyond 7 but most of it covered by elytra up to a ridge on which apex of elytra resting, ridge followed by an exposed, strongly sculptured area unless abdomen curved upwards into elytral cavity and then not exposed. Sternite 8 indistinct, membranised. Sternite 9 robust, largely as in Fig. 127, with more intensely pigmented, strongly diverting broad arms and a paler laminate expansion on one (right) arm. Tegmen with complete ring and no parameres. Aedeagus slightly to considerably longer than abdomen, main body varying in length in relation to apodemes; apodemes ventrally articulated with a clear gap; dorsal surface (tectum) pigmented or membranous; internal sac with or without basal sclerite, in either case with abundant wall vestiture or armature; gonopore dorsal at base.

Female: tergite 8 (Fig.124) weakly pigmented except against a nearly truncate, shallowly crenulated apex, with short setae in crenations. Sternite 8 largely membranous except for two arms and an apodeme. Hemisternites pigmented, broad, with small stylus; bursa large, ventrally deeply constricted at base, densely, finely crinkled throughout, with spermathecal duct insertion ventrally at base if male lacking basal sclerite (Fig.133), or at end or halfway towards end if male having a basal sclerite (Fig.126); spermatheca falciform, with duct and gland well apart on outer margin; gland small, duct insertion on body itself, not on extension.

DISTRIBUTION. — New Caledonia, Loyalty Islands.

HOSTPLANTS. — The species of Strabonus are expected to be stenophagous on specific dicots and their numbers increased substantially. Hostplant of one species is Syzygium cumini (Myrtaceae) , that of the others remaining unknown.

ETYMOLOGY. — ‘Strabónus’ from the Greek ‘strabón’, or ‘strabós’, meaning cross-eyed, because of the dorsal proximity of the eyes; gender masculine.

REMARKS. — The Strabonus features seem to accord with those of Rhamphini because of dorsolateral eyes, strongly, backwards curved sides of ventrites, dorsally carinate and sulcate tibiae, distinctly uncinate fore and middle but not hind tibiae, divaricate claws with broad lamina at base, and an exposed pygidium in male. The genus is proposed to accommodate a species that Perroud (1865) described in and attributed to Rhynchites . Seven further species are described, but others are present, including one without a tooth on femora, which were received too late for inclusion in the paper.

KEY TO SPECIES OF STRABONUS

1. Stria 10 impunctate from beside hind area of metepisternum to hind margin of ventrite 4 to appear as a finely engraved line. Pubescence on declivity directed obliquely outwards ......................... 2 — Stria 10 distinctly punctate throughout. Pubescence on declivity directed straight apicad ............ 7

2 (1). Designs of white scales absent ............................................................................................................... 3

— Designs of white scales present ..................................................................................................................... 4

3 (2). Pronotum coarsely punctate, transversely strigose, with intervals between puncta shiny. 2.3- 2.9 mm. New Caledonia..................................................................................................................... kanalensis — Pronotum finely punctate, not transversely strigose, remainder of surface dull with alutaceous minisculpture 2.0- 2.7 mm. New Caledonia................................................................................... caledonicus

4 (2). White scales on scutellum and metepisternum. 1. 7 mm. New Caledonia................ albiscutum — White scales forming a stripe on either side of pronotum ..................................................................... 5

5 (4). Pronotum and elytra largely glabrous. Tooth on fore and middle femora of same size. 2.0- 2.9 mm. New Caledonia............................................................................................................................... glabratus — Pronotum and elytra abundantly pubescent. Tooth on fore femora much smaller than on middle femora ..................................................................................................................................................................... 6

6 (5). Fore femora with a small tooth. Integument uniformly black and intensely blue. White pronotal stripe densely squamose. Male: aedeagal body stout, less than 3 x as long as wide, not longer than apodemes, parallel-sided for most part, Figs 134, 135. 2.6-3.0 mm. New Caledonia............. vitticollis — Fore femora with absent or obsolescent tooth. Integument of elytra and most of underside dark reddish brown, that of prothorax and head darker. Male: aedeagal body more than 4 x as long as wide, 2.2 x longer than apodemes, tapering for most part. 2.1-2.6 mm. New Caledonia........ unionis

7 (1). Interstriae punctate, not asperate. 2.5-3.0 mm. New Caledonia........................................... altulus — Interstriae asperate like sand-paper. 2.7-3.5 mm. New Caledonia.......................................... sabulosus