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Charles DeRoller
Member Nathrius
2 Posts |
 Posted - 12/02/2012 : 04:04:29
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Hello, and thank you for reading.
I want to determine the extent of Batocera kibleri.
From all of the records I can find, kibleri exists on Buka, Bougainville, and Guadalcanal. I can find no records of other locations.
There is some 1000km between southern B-ville and Guadalcanal.
B. lamondi occurs only on Malaita, which is part of the northern chain of islands.
I suspiciously suspect the major Batocera in Solomons to reflect the Ornithoptera victoria, though described as separate subspecies along the B-ville/Choiseul/Isabel/Guadalcanal chain, the differentiation is slight, as compared to those very unique subspecies of O. victoria from New Georgia and Malaita.
If Batocera follows O. victoria distribution, then B. kibleri should be found on Choiseul and Isabel.
However, I can find no records of such. And, despite having spent months in New Georgia, I found no major Batocera specimens.
I welcome any insight and records of Batocera from Choiseul and Isabel.
Thank you. |
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Francesco
Forum Admin
Luxembourg
9454 Posts |
Posted - 12/02/2012 : 08:23:25
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Hello Charles!
I do not think that the distribution of these species is comparable, due to different biology and physic reasons.
Accordingly, Casadio and I published in the "Contribution to the Cerambycid Fauna of the Solomon Islands" (Entomapeiron NS 1), No entomologist considered the fact that such islands have a volcanic origin and that only a very small group of them were connected among them by earth bridges during Glacial Ages.
These facts imply that their colonisation occurred mainly through occasional means: buoying logs and cyclones.
The oceanic currents, which go south-westward perpendicularly to the islands, seem to have only a local importance. In contrast, the South Pacific cyclones, which go south-eastward from New Guinea to the Fiji, just according to the main direction of the islands, seem to have a main importance.
Nonetheless, if the spreading of these insect is - as we think - exclusively based on cyclones, their different phenology (Batocera nocturnal, Ornitoptera diurnal) and the different physic resistance of their bodies might have been relevant consequences.
Accordingly, the relative delicacy of butterflies might have only allowed a short-distance spreading, island after island, while the robust Batocera might have covered safely long distances.
In the latter case, the case might have played a relevant role.
All this without e.g. considering the different distribution of their hosts. |
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Charles DeRoller
Member Nathrius
2 Posts |
Posted - 23/02/2012 : 04:04:03
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Thanks for the response!
John Tennent in Butterlies of Solomon Islands does a good job of discussing the distribution patterns of flora and fauna throughout the Solomons chain. The comparison to Ornithoptera is, as you cite, clearly flawed; it was the simplest correlation I could think of.
But my question really has to do with the distribution of kibleri. I am not an expert on Batocera, so neither have nor know of volumes that may examine the species in detail. So it is possible that the distribution of kibleri has been established beyond Bougainville and Guadalcanal; but if it has I cannot find such records.
It has always struck me as unlikely that kibleri exists only on Bville and Gcanal; your premise on cyclonic distribution is interesting and would explain such a binary distribution. However, most cyclones track east to west; but when I checked historical records with the Aussie Met. Svc. there have been cyclones that traveled west to east. So certainly, if the species originated on Bville, it could have been carried by cyclone to Gcanal.
The basic question still remains: does anyone have any records of kibleri occurring in the Solomons chain outside of Bville and Gcanal?
Thanks so much for your time and insight!
Charles |
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Robert Perger
Member Nathrius
Germany
7 Posts |
Posted - 16/04/2012 : 00:41:16
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Another plausible explanation for long distance dispersal is larval drift in logs via sea currents.
This would be quite consistent with distributional pattern of land crabs, their planktonic larvae also drift between islands.
On some small islands might not be enough suitable trees (but predators) to maintain a population of emerging long horn beetles, which would explain distributional gaps. That larger beetles drift wider is also plausible, their larval development takes longer... |
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Batocera (kibleri) in Solomon Islands
