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Northern Germany, Schleswig-Holstein, Schenefeld near Hamburg, at an uncultivated natural area near a small rivulet, 25 m, Outsidefoto: kuv, 8th of May 2015. Perhaps Brachyopa dorsata? Please help.
Kuv

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2nd pic:

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3rd pic:

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Please also here: One more chance to ID.
Greetings Kuv

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Hello kuv,

it should be Brachyopa panzeri due to lack of bristles on scutellum but i don't know if this feature is useful for id or not. see a recent post with similarity:
https://diptera.info/forum/viewthread.php?thread_id=92897

Best wishes,
John

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Hi John,
thank you very much :) that you point me to B. panzeri. I think you are right, as I now found the following charakteristic features of these flies: Antenna not plumose, thorascic dorsum reddish-brown, and segment 3 of the antenna with a pit close to the margin (the last feature is at the pictures of "my" fly not very clear).
Greetings Kuv

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Hello Kuv & John,

I would not identify the species from these photo's. Also in this post: https://diptera.i...ost_385532
I've taken the Dutch material of both species in my collection and compared them. Based on the male specimens and their terminalia I can accurately pinpoint the correct species. The only reliable external feature is the size of the sensory pit on the third antenna segment. Both species have scutellar bristles. Those of B. panzeri are paler than those of B. dorsata. But the bristles can be very short and from these photo's very difficult to see.
I'd say B. dorsata/panzeri, in both posts.

Kind regards,
Ectemnius

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Ok and thank you Ectemnius :).
I''l change headline.
Greetings Kuv

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Hello kuv and Ectemenius,

I don't have a specimen. I'm judging the scutellum based upon the following document (and i think that the 3rd photo is sharp enough to judge black bristles):

https://assets.ar...000332.pdf

I'm certainly not an expert and i have little experience with Brachyopa (I currently only have B. bicolor). Thank you for posting, Ectemenius.

Best wishes :),
John

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Hi John and Ectemnius,
first thank you John :) for your information. To have a "last chance" of ID I put an enlargement of the part of scutellum, hoping, Ectemnius :), to get a statement (although I have no better picture of the antennas).
Greetings Kuv

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2nd enlargement:

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Hello kuv,

I mentioned before that i don't know if the black hairs on the scutellum is a reliable feature or not. I don' have a specimen. However, i considered other features along with the scutellum when i suggested B. panzeri. To quote one of my recent posts:

"My determination is based upon the many notes/descriptions that i've read. The most recent document that i've studied is authored by Dr. Merz of Switzerland. The document is written in French but it can be translated using Google translate:
https://www.unige.ch/sphn/Publications/A…2_Merz_62_2.pdf

"In addition, the wings of B. panzeri are often variably browned at the edge and on the vena spuria (midrib of the wing that fades in the middle of the R5 cell) (Fig. 4), but the wings are completely transparent at B. dorsata. This latter character is only found in recent descriptions (from Speight 2008) despite the accompanying drawing of Panzer's description (1798) which clearly shows the partially dark wings."

The darkened wings diagnosis is not contested by Dr. Merz. And clearly the vena spuria and the edges of the wings are darkened on the species in your photos. I think that B. panzeri is a better match. See another photo of B. panzeri with darkened wings at spessart website:
http://www.spessart-fliegen.de/diptera/s…zeri/1/habd.JPG

Jürgen Peters has photos of a Brachyopa sp that fits well with the description of Brachyopa dorsata:
Gute Nacht-Schwebfliege vom 24.04.10 -->Brachyopa dorsata/panzeri

Please review the photos from Jürgen. Notice that the vena spuria is not darkened and the wing edges are clear/hyaline."

I find that the species is a good match for B. panzeri but i am not an expert and i do not yet have a specimen. another quote from one of my posts:

"I hope to find both B. dorsata and B. panzeri to study these features and fortify the descriptions with genitalia."

Best wishes,
John

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Hello kuv,

I based the id of your photos from the other post, as i do believe that they are of the same species. I did not carefully examine your photos. I usually require reading glasses because my vision is slipping. However, i can clearly see a large pit on the inside of the antennae, which confirms B. panzeri according to various keys. The pit is much smaller on B. dorsata. Microscopic examination is not necessary due to the large visible pit.

see my attached crop of your photo with this diagnostic pit. Also see a magnified pit at spessart website: http://www.spessart-fliegen.de/diptera/syrphidae/brachyopa/brachyopa_panzeri/IMG_2443.html

I do not place ego before science but it doesn't mean that i am absolutely correct. I think that this is Brachyopa panzeri. I also think that the species in the other photos is also B. panzeri: https://diptera.info/forum/viewthread.php?thread_id=92897&pid=385532#post_385532

Best Wishes,
John

ps: see figures 4 and six in the following document.
https://pdfs.semanticscholar.org/9234/1e5f32fa145698452ee9f8368fbec9e3b52f.pdf

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Hello kuv,

before i rest my case, i want to cross examine the size of the pit so that the size becomes relevant sans microscopic examination.

I may have discovered yet another weak scientific encryption and cracked it. Or it is a coincidence (as protectionist conspiracy theories are concerned.) Do notice that the numbers of the figures are four and six. In order to judge size differences, one must figure out a method to prove the size based on a photo of the pit. In doing so, my first thought is to see how many times the pit will fit inside of the antennae. When i test this method, the amount, surprisingly, is four times for panzeri and six times for dorsata. According to the drawings from experts of Brachyopa. When i test this measurement using your photo, i arrive at four times. Thus, it fits with B. panzeri. The pit on the photo at spessart also fits into the antenna four times. The pit in jarjar's photos (Christoph) also fits four times.

I think that B. panzeri is a fine id based upon all of this data.

I will attach images to illustrate this concept.

Best wishes,
John

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kuv's photo: pit fits four times

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Characters on pictures support all B. panzer. From Schleswig-Holstein hundreds of specimens of this species are recorded, mostly bred from fresh stumps of Fagus and Acer (same habitat as Merz reported in his paper) while there is only a single, doubtful record of B. dorsata. B. panzer is generally associated with deciduous forests as it seems to be typical for the Schenefeld area while B. dorsata is living in coniferous forest. General distribution and habitat are speaking as well for B. panzer.
Xylo.

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Wooooooooooooooooooooooooooooooooooooooooooooow John :) – I'm impressed to your work in helping me to find the right ID. Thank you very much! Now I have to study these new informations ... Note: Of course all of my pictures in this thread are from the same fly.
Greetings Kuv

I just see, that Xylo supports John's ID:

Thank you very much Xylo :)
Best regards Kuv

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Hello John, Xylo and Ectemnius,
once more thanks to all of you. After reading and checking John's (and Xylo's) arguments I think it must be B. panzeri.
John :) , it's a very nice work!
Greetings Kuv

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Hello kuv,

All is good. I'm happy that you have an id. I like Brachyopa. I find them to be most interesting from this family (Syrphidae.) Anyway, i did some more research on the black bristles of the scutellum and i discovered that Speight uses this feature in his keys to Brachyopa: https://diptera.info/downloads/StN_KEYS_Glasgow_2011.pdf

So it is a valid method of identification. Speight is a leading expert of Syphidae as far as i know. My first post should have ended the conversation.

Thank you Xylo. Thank you Ectemenius.

Best wishes,
John

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Hello people,

Hopfully this is not taken as being inconsiderate. But experience has taught me that photo-id like this one can be too optimistic. I've had the experience of being painfully wrong. Having said that, I will publish a Therevidae new for the Netherlands based on a photograph in the coming month...

@Xylosoma, I would not identify the specimen based on habitat. In the Netherlands B. panzeri is more typical of mixed and coniferous woods and B. dorsata more common than B. panzeri and typical of deciduous woods...
Btw, do you have a reference for that Merz paper. Or even better could you send a .pdf?

@John, that is (again) some very impressive detective work! It is certainly new to me that not the presence of bristles, but the colour is seen as diagnostic.

And as to your comment: "My first post should have ended the conversation."
Hopefully not, as I think we've learned quite a lot. And I'd enjoy that we respectfully disagree, converse and learn from each other in the future...

Kind regards,
Ectemnius

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Hello Ectemenius,

Congratulations on your first record! I am happy for you :)

Thank you for the kind words.

I am not a Doctor of Biology but I think that Brachyopa panzeri is identifiable by photo if the photo(s) are of a good enough quality depicting necessary features. Dr. Speight has black scutellar bristles in his keys to Brachyopa dorsata/panzeri. If the black bristles are not reliable, then the error is on his part. I assume that the size of the pit and the black scutellar bristles are diagnostic since these features are used in keys. Clearly, the pit is larger than the diameter of the arista which will exclude B. dorsata. I am comfortable naming this B. panzeri. Someday, i will find B. panzeri and i will key it by photo. Then i will verify this data using genitalia.

I most often identify my own specimens by photo alone. Probably 90% of the time. I am usually too busy to examine a specimen and dissect genitalia. My Wife can attest to this fact. I usually don't want to sit at the microscope. I learn more by trying to id by photo. I find keys and descriptions and study my photos of the live specimen. When i think that my id is correct, i will often write to an expert for confirmation. Sometimes genitalia is required and i have no choice but i still try to id it by photo.

I have identified a first record for Germany by photo alone. I sent the specimens to Paul Beuk for confirmation. Honestly, I have never examined the specimens. My photos were good enough to use the keys. However, i cannot publish the record because i am not a Doctor of Biology. I asked Paul if he could help but he seems to be too busy. I am building a website, which i hope to have completed by the end of the year, so i may have to publish the record myself by placing a pdf record on the website.

Anyway, I hope that you have a pleasant day and i hope that you find more first records for The Netherlands.

Best wishes,
John