---

Luc Bettinelli : France : Arc-et-Senans : 25610 : 27/04/2024
Altitude : 236 m - Taille : 5 mm ????
Réf. : 341727


Hello, for this Ephydridae, I think about Scatella paludum , but the opinions I've asked for are not unanimous (Philotelma is suggested, especially because the arista can appear plumose, even if it remains barely visible in the photo).

For my part I rely on habitus, wing pattern (pale spots), dorsocentral and acrostichal setae, colour of body and legs.

What do you think ?

I specify that the photo was taken near an unvegetated pond (Arc-et-Senans, France, april 27, 2024).

Best regards

Luc Bettinelli

---

According to the revision by Mathis et al. (2009) there is no species of Philotelma with several pale wing spots and entirely dark legs.

---

Thank you for that clarification.

I based myself on the British key available online from Drake (2006).

I had come to the same conclusion regarding the spots on the wings which didn't seem to me to match Philotelma.

On the other hand, I thought that we could not consider the legs as entirely black here (presence of a silvery pruinosity on part of the legs).


I find this individual very similar to photographs on the web for Scatella paludum, but the impression that the arista is plumose is problematic. Do you think this is a bad lead?

---

Plumose ordinarily means the hairs on the arista are as long as the width of the third segment of the antenna (to which the arista is attached). I do not see that.

Some species of Scatella have an enlarged pair of acrostichal bristles near the suture, like your fly has.

---

Thank you for these new interesting elements.



Luc Bettinelli : France : Arc-et-Senans : 25610 : 27/04/2024
Altitude : 236 m -
Réf. : 341882

Here is a reworked view (photo noise reduction) to better visualize why we thought the arista was plumose. Does this change anything for you?

And what do you think of the Scatella paludum hypothesis? Is this a species that is familiar to you or anyone else, and does this hypothesis seem good to you?
I rely on the arrangement of the spots (for the genus), on the acrosticals and on the erased side of the wing spots and on the silvery pruinosity for the species.
Thank you for your opinions !

---

Hello, note that I found a reference which describes the arista of Scatella paludum as obviously pubescent

---

Does anyone have any other opinion on the Scatella paludum proposal? or at least on confirmation of the genus? :|

---

It is definitely a Scatella species. The greyish colour and faint wing spots support S. paludum, but I can't confirm the species by this pictures. I do not see any trace of a long haired arista.

---

Thank you very much for your response and for this opinion which is in line with what we ultimately concluded !

---

I would say that the specimen is a little too dark, and the wing markings too clear for it to be paludum. I would suggest this is Scatella lacustris (formerly tenuicosta). Scatella paludum has very silvery pleurae and face (if you have any other photos).

---

Unfortunately, I don't have any other usable photo, and in particular no photo of the face. But thank you very much for this informed opinion.

---

In the French INPN repository, there is Scatella tenuicosta Collin, 1930 and Scatella stagnalis Fallén, 1813) synonymous with Ephydra lacustris Meigen, 1830. I'm a little lost.

---

S.tenuicosta is a synonym of S.lacustris. Scatella stagnalis is a good species, and should not be confused with lacustris. It has a very different appearance and structure.