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 Ephydrid from Potamogeton leaf mine
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| John Bratton |
Posted on 08-12-2021 15:37
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
25 March 2021 I collected some Potamogeton polygonifolius with mined leaves. Three ephydrids (I think) emerged in May, two females and a male. Here is the male. The site is a shallow weedy pond at Moelyci Farm, Tregarth, North Wales. Martin Drake's unpublished key mentions two species associated with Potamogeton: Hydrellia flavicornis and H. fulviceps. The genitalia of this fly are somewhat like those of H. flavicornis. But the fly doesn't key to Hydrellia- the lunule doesn't extend up to near the ocelli. And H. flavicornis is supposed to have yellow antennae and no strong presutural dorso-central. So, does anyone recognise it, please? John Bratton attached the following image:  [85.85Kb] |
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| John Bratton |
Posted on 08-12-2021 15:39
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
This shot is in alcohol so colour darker.
John Bratton attached the following image:  [84.42Kb] |
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| John Bratton |
Posted on 08-12-2021 15:39
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
Dry this time.
John Bratton attached the following image:  [171.35Kb] |
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| John Bratton |
Posted on 08-12-2021 15:40
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
Dry.
John Bratton attached the following image:  [113.14Kb] |
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| John Bratton |
Posted on 08-12-2021 15:41
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
In alcohol. Genitalia stowed.
John Bratton attached the following image:  [89.94Kb] |
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| John Bratton |
Posted on 08-12-2021 15:43
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
Genitalia prised out, from between a couple of shoebrush-like structures.
John Bratton attached the following image:  [123.21Kb] |
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| John Bratton |
Posted on 08-12-2021 15:44
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
Last photo. I thought I had pictures of the leaf mines but I don't. They will have to follow next year.
John Bratton attached the following image:  [167.26Kb] |
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| Tony Irwin |
Posted on 08-12-2021 15:55
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 Member Location: Norwich, England Posts: 7280 Joined: 19.11.04 |
John - check the mid femora for small pv bristles. If they're absent, I would say this is Hydrellia maura (though the genitalia are hardly like flavicornis). Don't worry too much about the low lunule - normally it would appear to be much higher, but it does vary a bit. H. maura is known to mine Potamogeton. If you are still concerned, I'd be happy to have a look at the male for you. Sorry - wrote this before seeing the genitalia pics. Will look at them closely now. Edited by Tony Irwin on 08-12-2021 16:02 Tony ---------- Tony Irwin |
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| John Bratton |
Posted on 08-12-2021 15:59
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
Thank you very much. I'll get back in a couple of days. |
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| John Bratton |
Posted on 10-12-2021 18:47
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
The mid-femora do have postero-ventral bristles, three in the middle and four at the base. See photo. So I guess that rules out maura. Also the genitalia don't match maura in Martin Drake's key. Or should I say your key? He credits you with the keys and he added comments.
John Bratton attached the following image:  [90.29Kb] |
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| John Bratton |
Posted on 10-12-2021 18:51
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
Here is another photo of the ?aedeagus. That is what I'd call it in a beetle. Not sure if it is the same term in a fly. Anyway, it is quite a good fit for fuscus and the fly will key to fuscus without too much forcing. Is that a species associated with Potamogeton?
John Bratton attached the following image:  [33.51Kb] |
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| Tony Irwin |
Posted on 10-12-2021 19:34
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Member Location: Norwich, England Posts: 7280 Joined: 19.11.04 |
Thanks for that John - I agree this does look like fusca. One of the characters for this species is the swollen mid tibia, which I think I can see in one of your pics. The species is known to mine Potamogeton. Edited by Tony Irwin on 10-12-2021 19:34 Tony ---------- Tony Irwin |
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| John Bratton |
Posted on 11-12-2021 15:07
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Member Location: Menai Bridge, North Wales, UK Posts: 654 Joined: 17.10.06 |
Thanks for the agreement. Yes the mid-tibia are slightly swollen in the middle but not so you would notice if you hadn't been told to look. I wasn't sure how much swelling to expect. |
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