CLOSED: Rhantus frontalis, Fam. Dytiscidae

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wallaby1 Lincoln, United Kingdom(Zone 8a) Jul 08, 2008

This one seems to be rare, but I have found some pics which lead me to believe my diving beetle is Rhantus frontalis

http://www.entomart.be/INS-0683.html

http://www.zin.ru/animalia/Coleoptera/images/h_800/rhantus_frontalis.jpg

This Yahoo group dytiscidae.org has it as their home page pic, only 6 members but I guess they are serious ones!

http://tech.groups.yahoo.com/group/Dytiscidae/

http://www.google.co.uk/search?hl=en&q=Rhantus+frontalis&btnG=Google+Search&meta=

http://images.google.co.uk/images?hl=en&q=Rhantus%20frontalis&um=1&ie=UTF-8&sa=N&tab=wi

The head and thorax pattern matches, and it has the pale margin around the elytra. I have looked at quite a few and no others came close enough.

http://upload.wikimedia.org/wikipedia/commons/d/d8/Reitter_Dytiscus_u.a..jpg

Any agreement on this, we are short on these in BugFiles.





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wallaby1 Lincoln, United Kingdom(Zone 8a) Jul 08, 2008

Side view

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wallaby1 Lincoln, United Kingdom(Zone 8a) Jul 08, 2008

I also have pics of a diving beetle larvae, in the same pond as this one was on. The beetle pics were taken on 8th June, the larvae on 3rd July.

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wallaby1 Lincoln, United Kingdom(Zone 8a) Sep 05, 2008

I've come across another beetle in the same genus, Rhantus suturalis which looks like mine too, maybe closer. The larva doesn't quite match, although it was from the same pond it can't be guaranteed to belong to the same beetle. There is a distinct stripe down the back of my larva, perhaps they vary slightly. They mature in approx. 3 weeks!

http://www.microcosmos.nl/beet1/rhantus.htm

Larva pics

http://www.microcosmos.nl/beet1/rhantusl.htm

More pics on this site,

http://www.koleopterologie.de/gallery/FHL03/fhl03.html

Rhantus suturalis is here, some stating it is rare. A recent pond coloniser.

http://www.google.co.uk/search?hl=en&ie=ISO-8859-1&q=Rhantus+suturalis&btnG=Search&meta=cr%3DcountryUK%7CcountryGB

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wallaby1 Lincoln, United Kingdom(Zone 8a) Sep 05, 2008

Now that I've looked again at Rhantus frontalis on the Dytiscidae Yahoo group, the pattern at the top of the head between the eyes looks more like mine than R. suturalis, being more like a tied bow shape. That is narrow on R. suturalis, so I'm opting finally for R. frontalis. The larva didn't match R. suturalis either.

Giving the dates I took the pics, barely more than 3 weeks apart and the fact that the larva mature about 3 weeks after the egg hatching, it fits, when the beetle climbed from the pond to the top of a reed it shot like a bullet over land.

I will leave this open for a short time longer, if no-one objects I will mark it solved as Rhantus frontalis and a likely larva of that.

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wallaby1 Lincoln, United Kingdom(Zone 8a) Sep 05, 2008

I found a name change which states Rhantus frontalis is now R. ericans, but that was from 1995 and a search for Rhantus ericans only brings up that one site!

http://www.esg.montana.edu/aim/coleop/coleop.html

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wallaby1 Lincoln, United Kingdom(Zone 8a) Sep 23, 2008

Marking this as solved, I will upload the pics into BugFiles as Rhantus frontalis. I think I could also risk putting the larva pic there with a mention as it being most likely belonging to R. frontalis for reasons given above.

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