pun_logo

The Society for the study of flies (Diptera)

Affiliated to the British Entomological and Natural History Society (BENHS)

You are not logged in.

#1 2017-12-11 19:11:05

SJThomas
DF Members
Name: Sam Thomas
From: Oxford
Registered: 2017-02-17
Posts: 6

Drosophila obscura?

Hi, I've just started trying to key some drosophilids and wondered if anyone could give me a pointer on this specimen?

It was taken in later November in Oxfordshire away from human habitation. It keys to D. obscura using the test key in the members area but seems to have to many teeth in the sex comb. Proximal 13, distal 12 as opposed to maximums of 11 and 9 in the test key and 5 and 8 in Fauna. Ent. Scan. Ratio of 1st and 2nd protarsomeres is c. 1.45.

Can't seem to fit it against any of the other species so is this just within the normal variation or have I gone completely wrong?

Many thanks for any assistance and please excuse the poor photos.


Uploaded Images

Last edited by SJThomas (2017-12-11 19:13:01)

Offline

 

#2 2017-12-12 00:00:21

Tony Irwin
DF Members
Name: Tony Irwin
From: Norwich
Registered: 2008-03-01
Posts: 687

Re: Drosophila obscura?

From your genitalia pics, I'd say you were in the right group with obscura. Can't suggest any other species it might be, but will ask these questions.
Are you certain the leg and the genitalia are from the same fly? Have you got any "standard" obscura from the same site. Have you got any associated females?
If the answers are yes, no and no, I'd make plans to re-visit the site when the weather warms up, or next Sept/Oct. If 13/12 teeth is within obscura range, it would be good to get the key fixed!

Offline

 

#3 2017-12-12 12:37:30

SJThomas
DF Members
Name: Sam Thomas
From: Oxford
Registered: 2017-02-17
Posts: 6

Re: Drosophila obscura?

Hi Tony, Thanks for your response. Good to know that I'm in the right group at a least. The answers to your questions are indeed yes, no and no, so looks like I'll have to go back and get some more material.

Offline

 

#4 2017-12-12 12:52:53

MJames
DF Members
Name: Michael James
From: Norfolk
Registered: 2008-04-02
Posts: 104

Re: Drosophila obscura?

I'm pretty sure this is D. subobscura based on the genitalia.

Compare your picture of the protarsomeres with the one here.

Offline

 

#5 2017-12-12 13:29:53

SJThomas
DF Members
Name: Sam Thomas
From: Oxford
Registered: 2017-02-17
Posts: 6

Re: Drosophila obscura?

Hi Michael,

Thanks for the suggestion. The sex combs look good and D. subobscura seems to be the only UK species in the group that falls within (or near) my  counts of sex comb teeth. I'll remeasure the protarsomeres later and have a look at the costal bristle-index. The only other thing I'm wondering is if the ventral bristles on the cerci look a bit long compared to the diagrams of D. subobscura?

Offline

 

#6 2017-12-12 14:53:08

MJames
DF Members
Name: Michael James
From: Norfolk
Registered: 2008-04-02
Posts: 104

Re: Drosophila obscura?

There are some pictures of D. subobscura on this site for comparison.

I'm not convinced the proportion of the protarsomeres is a very reliable characteristic. The appearance of the sex comb teeth and cerci look like a good match.

Offline

 

#7 2017-12-12 15:50:36

SJThomas
DF Members
Name: Sam Thomas
From: Oxford
Registered: 2017-02-17
Posts: 6

Re: Drosophila obscura?

Yes the images you linked look like a very good match, good to know not to rely on the protarsomeres ratio too much.

Many thanks for your help.

Offline

 

Board footer

Powered by PunBB
© Copyright 2002–2005 Rickard Andersson