Genyocerus diaphanus (Schedl)

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 : 34-35

Genyocerus diaphanus (Schedl)

( Fig. 8 )

Diacavus diaphanus Schedl, 1939: 384 .

Genyocerus diaphanus (Schedl) : Wood 1969: 118.

Diacavus assamensis Browne 1964: 760 . Synonymy: Schedl 1972b: 159.

Diacavus abdominalis Schedl, 1942: 218 . n. syn. (male only)

Diacavus philippinensis Schedl, 1942: 216 . n. syn.

Diacavus sexporus Schedl, 1942: 217 . n. syn.

Taxonomy: G. diaphanus was described by Schedl from the female only. The male was described by Browne (1962) from a specimen taken in association with the female. Schedl (1962) independently also described the male. We have compared the male holotype of D. abdominalis (NMW) , the male holotype and a female described by Schedl (1966) of D. philippinensis (NMW) and the male lectotype of D. sexporus (NMW) with a series of males and females in RAB's collection from East Malaysia (Sabah) and Brunei, which had earlier been compared with a paralectotype female and the male described by Browne (1962) of D. diaphanus (BMNH) . Only a single, somewhat variable species is represented, the males of which vary from 2.5–3.2 mm in length. The characters used by Browne (1964) and Schedl (1942) to distinguish the species intergrade in longer series. The number of mycangial pores present on the pronotum of the male varies from none to 2 or 3 on each side. In the female, the number of mycangial pores varies from 4–10 on each side of the midline. The two sides usually differ by no more than a single pore, but there is much greater variation between individuals. There is also variation in the shape of the male elytral teeth. The inner four teeth on each side may be parallelsided or tapering, and bifid to almost truncate at the tip. The fifth, outer tooth varies from acutely pointed to obliquely truncate. All females that we have seen, with the exception of the supposed female of D. abdominalis , have the same type of frontal ornamentation and are essentially indistinguishable. Schedl (1942) noted that the single female of D. abdominalis , badly damaged and collected at a locality over 1800 km from that of the male holotype, 'könnte ... das zugehörige Geschlecht sein' and labelled this specimen as the allotype of the species. However, the frontal ornamentation is not of the type found in G. diaphanus , and Schedl's 'allotype' is in fact a female of G. pendleburyi .

Distribution: G. diaphanus is widespread, occurring from India through Southeast Asia to Borneo and the Philippines. It has frequently been intercepted in dipterocarp timber imported to Japan (e.g. Schedl 1966, Ohno 1990b) and Korea ( Choo & Woo 1983). It is newly recorded here from northern Thailand.

New Records : THAILAND, Chiang Mai, C[hiang] M[ai].Univ., 300m, ex EtOH trap, various dates from 10.i.2005 – 4.iv.2005, (W. Puranasakul) (1 ♂, 3 ♀) ( CMU, RAB) .

Biology: The species, like its congeners, breeds primarily in trees of the family Dipterocarpaceae , and has been recorded from the following genera ( Anisoptera, Balanocarpus , Dipterocarpus , Hopea , Parashorea, Pentacme , Shorea , Upuna , Vatica ). There are a few records from trees of other families: Gonystylus (Thymeleaceae) ( Browne 1961a), Gluta or Melanorrhoea , Mangifera (Anacardiaceae) , Durio (Bombacaceae) , Palaquium (Sapotaceae) , Pterocymbium (Sterculiaceae) ( Ohno 1990b), but these involve small numbers of specimens. Ohno (1990b, as Genyocerus abdominalis ) records a total of 9851 (6938 ♂, 2913 ♀) specimens bred from imported logs of seven genera of Dipterocarpaceae , but only 24 (21 ♂, 3 ♀) obtained from imported logs of six non-dipterocarp genera. This suggests that breeding was very rare, if it occurred at all, in the latter.

Figures

PLATE 3. FIGURE 8. Genyocerus diaphanus (Schedl) dorsal view of male. FIGURE 9. Genyocerus exilis (Schedl) lateral view of male elytra. FIGURE 10. Genyocerus exilis (Schedl) lateral view of female head.