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Bug Spotlight!
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U.C. Riverside
Department of Entomology |
Photo
by: G.
Ballmer(c) |
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Xixuthrus
ganglbaueri Lameere by
Doug Yanega
The female in this photo is the
first known specimen of this species since it was first described in
1912; she will become the neotype specimen for the species, since the
original specimen was lost.
This is one of three species of Xixuthrus
that occur in
Fiji
(the other two are X. heros (Heer)
and X. terribilis Thomson),
and they are all rare and mysterious, despite their enormous size (from
8-15 cm [or about 3-6 inches], making them the second largest beetles in
the world ─ only Titanus giganteus is larger).
Highly prized, specimens of the adults of any of the three Fijian
species will sell for hundreds or even thousands of dollars each, and
they are few and far between. As
a result, most reside in private collections, rather than museums.
Reasons for the apparent rarity of the
three Fijian Xixuthrus are
still uncertain, but their scarcity may be due to life history
characteristics associated with their large size, or food plants.
Their larvae are considered special delicacies, on those rare
occasions when they are encountered by Fijians, so there are no known
specimens of the larvae, and those who have found them haven't made note
of the tree species involved. Recent
field surveys by the Wildlife Conservation Society and the Fiji
Department of Forestry, however, have found giant larval tunnels
averaging 5 cm in diameter in a threatened species of native hardwood,
with grubs in living trees with some dead wood.
Hopefully they can get adults, at some point, to confirm that
they're Xixuthrus. The larvae
may therefore require very large and/or rare host trees, and such trees
are uncommon in
Fiji
's cyclone forests and are becoming increasingly rare as widespread
logging actively targets big trees. A review of known localities for the
beetles initially suggests they may require intact native lowland
forest, as older specimens are from (or adjacent to) forested areas, and
most recent collections have come from adults flying to lights situated
adjacent to natural lowland forests, which are rapidly disappearing due
to logging and clearance for agriculture.
Of course, entomological surveys are few in
Fiji
, thanks largely to the rugged, inaccessible terrain and high rainfall,
so the rarity of Xixuthrus may
also be due, in part, to limited collections in remote areas.
Nonetheless, the clearest threat to their survival is habitat
loss, rather than collecting.
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