TRIBE CLYTINI

View Image Gallery of Tribe Clytini.

DIAGNOSIS : small cerambycin (~ 10 - 15 mm); head vertical or subvertical, ventral surface oblique at a point below lower eye lobe; eye finely facetted; prothorax cydariform or sometimes elongated, side rounded, never tuberculate; fore coxal usually rounded externally; its cavity open posteriorly; mid coxal cavity open to epimeron; scutellum. small, apex rounded, rarely angulated; elytra entire, generally dark-colored with white or yellowish lines or bands produced by combination of pubescence and color on disc itself, epimeron of metathorax angulated and produced over first abdominal segment and hind coxae; episternum of metathorax wide.

Note : Lacordaire had set three stringent axioms that the absence one determines to which genus a species should belongs. These three limitions are (i) the antennae extending at most a little beyond the base of elytra, (ii) the prothorax unarmed and (iii) the first hind tarsal segment at least 1/3 longer than the next two united (Pascoe, 1869). However, Gahan (1906) stated that axiom (i) and (iii) cannot be mantained. Some species have antennae that is twice longer than body while others have a short first tarsal segment or one that is 3 X as long as 2 + 3 united. As there are intermediate between these two extreme, the genera cannot be defined to a great degree of precision. Sarawak Clytinian also exhibit these two characteristics and supported Gahan's claim.

Key to genera of Clytini in Sarawak

1.     Apex of elytra not abruptly sloping ..………………………………………… 2 
Apex of elytra abruptly sloping .- Sclethrus, NEWMAN

2(1) Antennal insertion widely separated, as wide as lateral genal margin, area between not raised, moderately even; episternum of metathorax usually wide……………………………………………………………………………3
Antennal insertion very close; distinctively narrower than lateral genal margin; antennifer dentate, area between raised, concave; episternum of metathorax narrow………………………………………………………………………….4

3(2) Front carinate, with one or more branching carinae; antennae inserted under  prominent lateral edge or carinae that continued downwards along each side; antennal insertion slightly narrower than external genal margin  - Xylotrechus, CHEVROLAT
Fronts not carinate, squarish; no lateral carinae near eye that extended along side; antennal insertion as wide as external genal margin . - Perissus, CHEVROLAT

4(2) Antennal segment spied endoapically at basal segment . ...……………......… 5
Antennal segment not spine . - Chlorophorus, CHEVROLAT

5(4) Antennal segment 3, 4 & 5 spined endoapically; basal segments thicken apically or slightly clavate - Acrocyrta, PASCOE
Only antennal segment 3 & 4 spined endoapically; basal segments not thicken apically - Demonax, THOMSON

Note :  another 2 specimens in SM Coll. labelled Rhaphuma shelfordi Gahan were badly damaged beyond reidentification. They have the basic charasteristic of Rhaphuma especially greatly elongated body. However, the basal antennal segment 3 & 4 were clearly spined which suggested they belong to the genus Demonax.