Acronymolpus, a new genus of Eumolpinae, endemic to New Caledonia (Coleoptera, Chrysomelidae)

Abstract The genus Acronymolpus is proposed as new. It is represented by four new species, all of which are endemic to New Caledonia. Proposed are: Acronymolpus joliveti sp. n. (type species), Acronymolpus gressitti sp. n., Acronymolpus meteorus sp. n., and Acronymolpus turbo sp. n.


Introduction
Acronymolpus, a new genus of Eumolpinae, is proposed herein. The four included species are new and are endemic to New Caledonia. This genus is unique among its allied Eumolpini, e.g. Dematochroma Baly, by having the metacoxae enlarged and nearly reaching the posterior margin of the first abdominal ventrite.
Specimens appear to be very rare in collections, with only seven individuals known to date. This study is based only on these specimens representing the four new species.
The earliest examples were taken in 1963, then through later years to 2005.

Material and methods
Collections: BPBM, Bishop Museum, Honolulu, Hawaii; USA; CXMNC, Collection Xavier Montrouzier, Institut Agronomique néo-Calédonien, La Foa, New Caledonia, with a holotype from the latter to be deposited in the MNHN, Museum of Natural History, Paris, France.
Owing to the rarity of specimens, three of the species are left intact and not compromised by dissecting.
Measurements are taken from a calibrated ocular micrometer on a Leica MZ7 stereo microscope and are reported in mm and cmm, the latter = 1/100 of a mm. Abbreviations or brief names of selected body structures are: BL body length; BB body breadth; HB head breadth; IAS transverse breadth of interantennal space; AS transverse diameter of antennal socket; ORB transverse space of orbit between antennal socket and eye; IOS shortest transverse distance between eyes; EYE maximum diameter × breadth of eye; GENA distance between genal apex and lower eye margin; PNL pronotal length; PNB pronotal breadth.
Body fusiform, stout, with elytra strongly narrowed from robust basal region to preapex. Head: frontal surfaces flattened; postantennal swellings ± subtriangular or oblique, not conspicuous; oblique suture present, shallow internally, deeper along upper eye margin; coronal suture deep along mid-vertex; eye subovate. Antenna slender, elongate and attaining apical 1/3 or more of elytron. Pronotum convex with anterolateral area strongly descended and appearing narrowed in dorsal view; base broadly and shallowly biconvex; posterior angle small, ± dentate; lateral margin convex and narrowed anteriorly; anterior angle slightly produced, subangulate; disc moderately to strongly punctate. Scutellum small, triangular, surface nearly smooth. Elytral punctures basically arranged in regular striae but the inner discal rows quite obliterated and confused on the basal half before they become organized into straight rows apically. Elytral epipleuron narrow to preapex and continued to apex as a thin thread. Wing normally developed.
Ventral surfaces: prosternum subquadrate, flattened; hypomeron ± smooth, impunctate; metasternum broadly and gently convex, ± smooth; first abdominal ventrite ( Fig. 1C ) not quite trisected by enlarged metacoxae on each side but on dissection with thin shelf-like extensions beneath metacoxae; intercoxal piece of forming an acute, steeply inclined triangle anteriorad; remaining ventrites strongly narrowed posteriorly, collectively subtriangular in outline. Legs: femora subclavate; metacoxa enlarged; tibiae slender, subequal to femur length. Head: frontal surfaces smooth with hint of isodiametric sculpture; frons with a few large deep punctures mostly above middle; postantennal swellings ± triangular, surfaces nearly smooth; oblique suture becoming a deep sharp sulcus along upper eye margin; vertex with a few large deep punctures on each side near beginning of deep coronal suture; interantennal space flat, about 2.6 × as broad as transverse diameter of antennal socket; antennal socket and orbit with breadths subequal; interocular space about 1.4 × as broad as maximum eye diameter; eye subovate, moderately narrowed below; gena slightly over 0.6 × as deep as eye.
Prothorax: 0.57 × as long as broad; lateral margin moderately and evenly convex from base to apex; disc moderately punctate; central punctures somewhat ovate and commonly 1-2 × as large as interspaces; interspaces nearly smooth and shining with occasional micropunctures and nearly obsolete fine sculpture.
Elytron: smooth and shining; lateral margin beyond broad basal region strongly narrowed posteriorly to knob-like extremity at side of sutural apex; humerus weakly swollen, mostly smooth; discal punctures larger and deeper than pronotal ones and commonly 1-2 × as large as interspaces; interspaces commonly ± costate to subtuberculate.
Ventral surfaces: prosternum with surface dull-punctulate; hypomeron subshining, with obsolescent fine sculpture; metasternum broad, smooth-shining with fine sculpture, sparsely micropunctate; metacoxae nearly touching posterior margin of abdominal ventrite 1; relative lengths of abdominal ventrites (cmm): 48 : 10 : 10 : 12 : 20; surfaces subshining, with fine sculpture; first ventrite with median part acutely triangular and strongly inclined between coxae; last ventrite lacking median impression before apex.  Remarks. Near A. turbo, sp. n. in general stature, including the close proximity of the metacoxae to the apical margin of the first abdominal ventrite; both species also have ornamentation on the elytral preapex -knob-like in this species and briefly explanate in A. turbo. The name honors Prof. Pierre Jolivet of Paris, who has charted our knowledge of Chrysomelidae in general and of New Caledonia in particular.
Head: frontal surfaces with general isodiametric sculpture; frons with several large, deep punctures above; oblique suture weak internally, becoming deeper along upper eye margin; vertex bearing several large punctures on each side of shallow coronal suture which ends near mid vertex; interantenal space rough, about 2.6 × as broad as transverse diameter of antennal socket; antennal socket and orbit subequal in breadth; interocular space about 1.3 × as broad as maximum diameter of eye; eye subovate, narrowed below; gena 0.5 × as deep as eye.
Prothorax: 0.55 × as long as broad; lateral margin slightly narrowed basally to midpoint, then more convexly narrowed to acutely produced anterior angle; disc closely and confusedly punctate; punctures deep and commonly 3-4 × as large as raised interspaces; only the antebasal area narrowly impunctate.
Elytron: robust basally across humeral region, then strongly narrowed posteriorly to preapical area, marked by an apical explanate margin originating at preapex of 7 th interstrial interval; humerus briefly pustulate and smooth, and slightly heavier than inner basal costae; disc densely punctate-subtuberculate on inner part of basal disc where punctures are confused and about 1.5 × as large as pronotal ones; elytral interstices generally swollen, with a hint of microsculpture but nearly smooth and shining.
Legs Remarks. Differs further from its close relative, A. joliveti, sp. n., by having closer discal puncturation of the pronotum. The name refers to the stout, ± conical form of the elytra.
Head: frontal surfaces largely smooth, with a hint of fine sculpture; upper frons with a few large, deep punctures; postantennal swellings ± subquadratae; oblique suture becoming deep above eye; vertex with coronal suture deep, with surfaces on each side convexly swollen; interantennal space broad, flat, about 3 × as broad as antennal socket; orbit slightly broader than antennal socket; interocular space with breadth subequal to maximum eye diameter; gena not quite 0.5 × as deep as eye.
Prothorax 0.59 × as broad as long; base broadly convex across middle; lateral margin moderately convex; disc uniformly convex and rather uniformly punctured, punctures ± elliptical and commonly 1 × as large as interspaces; interspaces smooth with hint of microsculpture. Elytron smooth and shining; lateral margin moderately narrowed from posthumeral area to preapex; apex convex: humerus slightly produced, smooth; inner basal disc with punctures deep, and larger than pronotal ones.
Remarks. The less tapered body form of this species separates it from A. meteorus, sp. n., which is very strongly narrowed apically. This is the only specimen of the genus with any information on plant associates; in this case Freycinetia. The name honors the late J. Linsley Gressitt, who contributed greatly to entomology of the Pacific and beyond.
Head: frontal surfaces largely with fine, isodiametric sculpture; frons fairly closely punctulate above; postantennal swellings ± oblique, not conspicuous; oblique suture a fairly deep sulcus along upper eye margin; vertex below with several large punctures on each side, coronal suture deep at mid-vertex, then obsolete above; upper vertex with moderately large punctures centrally; interantennal space about 2.75 × as broad as transverse diameter of antennal socket, surface rough, punctate; antennal socket and orbit subequal in breadth; interantennal space slightly broader than maximum eye diameter (22 : 19); eye subovate; gena slightly over 0.4 × as deep as eye.
Prothorax about 0.60 × as long as broad; lateral margin nearly straight basally before convexly narrowed anteriorly; disc closely and heavily punctate, central punctures commonly 3-4 × as broad as raised interstices.
Legs: femora nearly smooth, with fine microsculpture; metatibia as long as femur, straight, surface with duller microsculpture than femur.
Measurements Remarks. The uniform piceous dorsal coloration along with the closely and deeply punctate dorsal surfaces mark this species. Differs from A. gressitti, sp. n. by the closer pronotal puncturation and the more narrowed elytral preapex. The name refers to the pitted surface of an iron meteorite.
Key to species of Acronymolpus gen. n. and the separation of this genus from other New Caledonia Eumolpini 1 First abdominal ventrite largely occupied by enlarged metacoxae; the metacoxae nearly reaching apical margin of the ventrite (Fig. 1C)  Pronotal disc with punctures commonly 1-2 × as large as interspaces; each elytral apex with a short broad rounded tubercle (Fig. 1B)