July 2013. A weevil from a guava grower in Palau, who is certain that it is damaging guava trees, although the damage was not described. What could it be?
There was a suggestion that it was the black short rostrum weevil. Family Curculionidae: Asceparnodes duplicatus.
However, it was more likely to be a member of the tribe Celeuthetini, which has a number of genera throughout the Pacific and SE Asia (including Oribius). It’s hard to identify it with certainty, however the most likely options are Celeuthetes, or Lophothetes. Celeuthetes has not been recorded from Palau before, but is in New Guinea and the Moluccas. Lophothetes has a distribution through New Guinea to the Caroline Islands and the Marianas Archipelago, so is a likely candidate, but Oribius is a possibility, though they tend to have distinctive markings on the elytra (see http://www.padil.gov.au/pests-and-diseases/Pest/Main/135561/884, But also http://www.padil.gov.au/pests-and-diseases/Pest/Main/135551/348).
It was assumed that the adults make semi-circular holes around the edge of the leaves. The larvae are soil-dwelling and feed on roots of (probably) a wide range of plants. Some research into the pest impact of a related genus in PNG has been published in the following paper:
Wesis P, Niangu B, Ero M, Masamdu R, Autai M, Elmouttie D, Clarke AR (2010). Host use and crop impacts of Oribius Marshall species (Coleoptera: Curculionidae) in Eastern Highlands Province, Papua New Guinea. Bulletin of Entomological Research 100(2): 133-143 http://dx.doi.org/10.1017/S0007485309006877
As an aside, the name given aove (Ascepsrnodes duplicatus) is from Zimmerman’s Australian Weevils plates (Volume V, plate 180). The genus is an unavailable name that is awaiting publication of the text volume to the Entiminae before it is validly published. Use it with caution!
From the Australian Museum: It is definitely not ‘Asceparnodes duplicatus’. There is a photo in Zimmerman’s book (Australian Weevils plate 180) of a beetle named Asceparnodes duplicatus, but it has no nomenclatural validity – the name Asceparnodes has never been formally described (its probably one of Zimmie’s many nomina nuda – he published the photos first then died before he published the taxonomy). You can check the name against the catalogue published by Alonso-Zarazaga & Lyal (1999 & updates) & also Zoo Rec (it’s in neither). And the beetle in Palau is absolutely nothing like this photo anyway! There is an Asceparnus, a small genus of short-noses in Australia, but it is also nothing like the beetle in Palau. As I said, the Palau weevil looks like things I’ve seen in Fiji & Solomon Islands, so I imagine it belongs to a widespread Pacific group.