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 Stratiomys or Odontomyia larva?
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| Smoggycb |
Posted on 05-08-2010 15:21
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Member Location: Posts: 350 Joined: 19.05.07 |
Photographed today, Rye, East Sussex in a brackish pool. I thought at first that this must be Stratiomys, as many S, singularior egg-laying here. However, the short last segment and pale stripes do fit the description of Odontomyia ornata in Stubbs & Drake. Can anybody help!?
Edited by Smoggycb on 05-08-2010 15:25 |
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| atylotus |
Posted on 05-08-2010 17:16
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 Member Location: Posts: 1112 Joined: 29.05.09 |
Dear Smoggycb It is not Stratiomys, but i cannot decide whether it is Odontomyia or Oplodontha. What's the size? if it is about 3 cm then it must the last instar of O. ornata. If smaller (less then 1.5 cm) then you have to check the presence of a brush of hairs at the ventral median part of the head. If present=> Oplodontha, if absent=> Odontomyia (most likely O. tigrina). Does it have a few long hairs or numerous smaller hairs? By the way, larvae of S. singularior and S. longicornis have numerous small white dorsal spots which indicate the position of a hair-implant. This is very good to see, even in the field. Edited by atylotus on 05-08-2010 17:17 |
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| Smoggycb |
Posted on 05-08-2010 17:52
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Member Location: Posts: 350 Joined: 19.05.07 |
I would say this was between 3 and 4cm long, certainly much more than 1.5cm, so it looks like O. ornata. Thanks very much atylotus. By the way, I always though O. ornata was exclusively freshwater, but there was a record of the larvae of this species from the same pool about three years ago - is this usual for this species?
Edited by Smoggycb on 05-08-2010 17:53 |
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| atylotus |
Posted on 05-08-2010 19:52
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Member Location: Posts: 1112 Joined: 29.05.09 |
Dear smoggycb O.ornata (as a larva) prefers fresh water (< 300 mg Cl/l), but she is able to withstand slighty brackish water of up to about 500-600 mg Cl/l. How brackish is your pool? Do you intend to breed this larva? If so, could you tell me if it will become a female or a male? Best wishes atylotus |
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| Smoggycb |
Posted on 06-08-2010 16:48
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Member Location: Posts: 350 Joined: 19.05.07 |
Most recent (three days ago) conductivity reading was 19.47 milli siemens, but it does drop as low as about 4.5. Don't know my conversions unfortunately, but the second reading is about a third sea water (53 milli siemens ish). I didn't take the larva to bred unfortunately, but I think I may go back and se if I can find it again to try. |
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| atylotus |
Posted on 08-08-2010 08:53
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Member Location: Posts: 1112 Joined: 29.05.09 |
Dear Smoggycb I would guess that 19,47 mS is 19,47 mS/m (?) which is the equivalent of about 6800 mg Cl/l. If so, than 4.5 mS/m is the equivalent of about 1500 mg Cl/l. This is very high for O. ornata. I didn't even know that this species is able to survive such a high conductivity and even such fluctuation. In such high conductivity the conductivity is mostly caused by chlorine, instead of other ions. |
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| Smoggycb |
Posted on 08-08-2010 15:20
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Member Location: Posts: 350 Joined: 19.05.07 |
I attempted to re-find the larva today but no luck. I will try again tomorrow. This is a curious little pool. It has brackish species such a Stratiomys singularior and S. longicornis and more freshwater species such as Hairy and Emperor Dragonfly and Plea minutissima (and O. ornata!) |
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but don't see the image in the post.
