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 Scatella
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| Nikita Vikhrev |
Posted on 31-08-2006 19:45
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 Member Location: Posts: 9193 Joined: 24.05.05 |
Moscow region, 31 aug, 2,5mm S. stagnalis? It sits on leach with some reason or without? Nikita Vikhrev - Zool Museum of Moscow University |
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| Tony Irwin |
Posted on 31-08-2006 20:46
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 Member Location: Posts: 7168 Joined: 19.11.04 |
Scatella tenuicosta - very similar to stagnalis, but the most distal spot in the wing is shaped like an hour-glass (or Coca-Cola bottle  ). In stagnalis this spot is more oval. All Scatella feed on diatoms and desmids, so there's no reason for it to be on a leech - perhaps it's just a good place to view the crowd. (The male is on the leech, the female on the leaf.)
Tony ---------- Tony Irwin |
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| Nikita Vikhrev |
Posted on 31-08-2006 20:59
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Member Location: Posts: 9193 Joined: 24.05.05 |
What an easy way to separate two species! Thank you Tony! Nikita Vikhrev - Zool Museum of Moscow University |
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| Tony Irwin |
Posted on 31-08-2006 21:14
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Member Location: Posts: 7168 Joined: 19.11.04 |
I should point out that not all tenuicosta show the "waisted" spot. Some of them have a less obvious triangular spot, but in all the specimens I've seen, the spot widens anteriorly (towards R4+5). In stagnalis the spot can also be various shapes but never widens anteriorly. And don't forget there are other species with which they can be confused  though these two are the most common and widespread.
Tony ---------- Tony Irwin |
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but don't see the image in the post.