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#1 2017-10-19 15:13:34

conopid
DF Members
Name: Nigel Jones
From: Shrewsbury
Registered: 2008-02-27
Posts: 637
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Confused by Sphaeroceridae wing venation terms

Pitkin's Sphaeroceridae key always confuses me, as the terminology for wing veins does not appear (to me at least) to be consistent, with terms swapping around between two terminologies in different parts of the key. I want to check that I am interpreting the terms correctly. Can anyone look at the attached and comment on the following:

1. Have I got the positions of Pitkin's M1+2 and M3+4 right?

2. Just where is the cubital vein as referred to in couplet 34 on page 41? "wing vein R4+5 distinctly sinuous; CUBITAL vein not extending beyond medial-cubital cross-vein. junction rounded (fig. 225)."

Now, in Fonseca's Dolichopodidae key the cubital vein is R4+5, but clearly, here that is not what is intended, so is the cubital vein the same as Pitkin's vein M? Or am I completely misunderstanding the terminology in this key?

I am vexed!


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Last edited by conopid (2017-10-19 15:28:33)


Nigel Jones
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#2 2017-10-19 19:45:10

conopid
DF Members
Name: Nigel Jones
From: Shrewsbury
Registered: 2008-02-27
Posts: 637
Website

Re: Confused by Sphaeroceridae wing venation terms

I am still unsure about Pitkin's cubital vein, but have resolved the M veins by consulting Oldroy'd RES Diptera introduction handbook (which I always forget is a very useful reference for this sort of stuff).


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#3 2017-10-19 22:43:04

Tony Irwin
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Name: Tony Irwin
From: Norwich
Registered: 2008-03-01
Posts: 663

Re: Confused by Sphaeroceridae wing venation terms

Brian explains the venation terminology on pp 21 and 22 of the Handbook. His cubital vein (= M3+4 of Rohacek) is marked as CuA1 on your diagram. The round-ended cell in Fig.225 is bordered by the M vein in front, and the cubital vein behind, with the round end being the M-Cu cross-vein. In Fig 224, the cubital vein extends for a short distance beyond the M-Cu cross-vein.

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#4 2017-10-20 11:12:33

conopid
DF Members
Name: Nigel Jones
From: Shrewsbury
Registered: 2008-02-27
Posts: 637
Website

Re: Confused by Sphaeroceridae wing venation terms

Thank you Tony, that is very helpful and confirms what I had thought might be the case, i.e. M3+4 is in fact the same as the part of the cubital vein beyond cross vein M-cu. I find that confusing and can't understand why the term M3+4 is used as well as cubital vein.

Last edited by conopid (2017-10-20 12:02:28)


Nigel Jones
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#5 2017-10-20 11:55:44

Tony Irwin
DF Members
Name: Tony Irwin
From: Norwich
Registered: 2008-03-01
Posts: 663

Re: Confused by Sphaeroceridae wing venation terms

It's down to how the veins are interpreted - Rohacek considered the 5th vein to be part of the median series, so refers to it as M3+4, Pitkin prefers to call it a cubital vein, and while it can be confusing, it doesn't really matter who's right, as long as the terms are explained. Either way, it's the whole vein (not just the bit beyond the cross-vein) that is labelled M3+4 or CuA1. Occasionally both interpretations may be used in one key - that shouldn't happen and does get confusing!

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#6 2017-10-20 12:01:00

conopid
DF Members
Name: Nigel Jones
From: Shrewsbury
Registered: 2008-02-27
Posts: 637
Website

Re: Confused by Sphaeroceridae wing venation terms

Thanks again Tony. Yes it's the use of two terms for one feature in the same key that is confusing. Thanks for clarifying.


Nigel Jones
Shropshire

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