Genyocerus frontalis (Strohmeyer)

Beaver, R. A. & L. - Y, 2007, A review of the genus Genyocerus Motschulsky (Coleoptera: Curculionidae: Platypodinae), with new synonyms and keys to species, Zootaxa 1576 (1), pp. 25-56 : 36-37

Genyocerus frontalis (Strohmeyer)

( Figs 11–14 )

Diapus frontalis Strohmeyer, 1914b: 5 .

Diacavus frontalis (Strohmeyer) : Schedl, 1939: 364.

Genyocerus frontalis (Strohmeyer) : Wood, 1969: 118.

Diacavus haticollis Browne, 1962: 217 .

Diacavus laticollis Browne, 1964: 753 (justified emendation). n. syn.

Taxonomy: Diapus frontalis was described from a single male collected by G. Doria in Borneo ( Sarawak) in 1865-66 and deposited in the Stettin Museum. Wood & Bright (1992) state that the type is presumed lost; however, Wegrzynowicz & Mokrycki (1996) list a 'syntype’ in IZW. We have examined this specimen. There can be no doubt that it is the holotype of the species. It was evidently seen by Chapuis, who indicates on one of the eight labels below the specimen that it is a new species, but did not describe it. We have compared the holotype to a series of specimens from East Malaysia (Sabah) (ZMLU), which had earlier been compared to the holotype male of Diacavus laticollis Browne from West Malaysia (BMNH). Only a single species is represented. The previously unknown female is described below.

Female: Generally resembling male, 3.7–3.8 mm long (excluding frontal hair brushes and part of abdomen extending beyond elytra), 2.9–3.0 times as long as wide. Frons with antennae inserted on upper part of frons close to upper margin of eyes, brushes of long, golden–yellow hairs present in young females both above epistoma and on upper part of frons (Figs 13–14), a large teardrop–shaped, shallow, shining, impunctate impression on each side, extending from vertex to lower quarter of frons, the impressions separated by a narrow, median carina, upper part of frons lateral to impressions flat, bearing on each side a large brush of hairs, extending dorsally well above antennal insertion and nearly meeting medially just below vertex, the majority of hairs directed forward, downcurved at tips, each brush extending ventrally in a narrow band close to inner margin of eye nearly to its lower margin, the lowest group of hairs longer and incurved towards midline; epistomal brushes divided into two parts on each side, the long hairs upcurved below those of the upper brushes, almost reaching vertex, lowest part of frons below impressions finely punctured, the punctures with much shorter erect hairs, normally concealed below epistomal brushes. Pronotum 1.05–1.1 times longer than wide, similar to that of male but with 9–12 large mycangial pores on each side of midline close to base (Fig. 13), rather than 0–2 as in male. Elytra wider than and about 1.6 times as long as pronotum, 1.5 times longer than wide, carina on base of elytra reduced and more rounded, striae less strongly impressed, becoming obsolete in posterior third of elytra, interstriae with sparse, semi–recumbent hairs, elytral apices lacking teeth, separately rounded, with more abundant short hairs.

Female specimens examined: MALAYSIA: Sabah, Sipitang, Mendolong , 28.xi.1987, 6.v.1988, 13.v.1988 (S. Adebratt) (5 ♀) ( ZMLU, RAB) .

Distribution: The species is recorded only from East Malaysia ( Sarawak) and West Malaysia. It is newly recorded here from Brunei Darussalam and Sabah.

New records: BRUNEI: 4 o 34'N, 115 o 7'E, Kuala Belalong FSC, Dipterocarp forest, site 1, 260m alt., Fog 8, 9.viii.1991 (N. Mawdsley) (1 ♂) ( BMNH) ; Temburong, nr. K. Belalong Field Stud. Centre, 4 o 33'N, 115 o 09'E, 150m, 1.iii.1992 ( R. A. Beaver) (3 ♂); as previous except: 200m, ex Shorea sp. , 10.iii.1992 (2 ♂) (all RAB) ; [ MALAYSIA (Sabah)] North Borneo ( SE) , Forest camp, 19 km. N. of Kalabakan , 60m., 13.x.1962 (Y. Hirashima) (1 ♂); as previous except: 21.x.1962 (1 ♂); as previous except: 19.x.1962 (K. J. Kuncheria) (1 ♂) (all BPBM) ; MALAYSIA: Sabah, Sipitang, Mendolong , 28.xi.1987, 6.v.1988, 13.v.1988 (S. Adebratt) (1 ♂, 5 ♀) ( ZMLU, RAB) .

Biology: The only host record is from the dipterocarp tree Shorea leprosula ( Browne 1962) .

Figures

PLATE 4. FIGURE 11. Genyocerus frontalis (Strohmeyer) dorsal view of male. FIGURE 12. Genyocerus frontalis (Strohmeyer) lateral view of elytra, showing membranous extension of apical margin of fourth abdominal ventrite. FIG- URE 13. Genyocerus frontalis (Strohmeyer) dorsal view of female head. FIGURE 14. Genyocerus frontalis (Strohmeyer) lateral view of female head.