---

I spotted this small fly (length approx. 4mm) in Lacanja, Chiapas province, Mexico, near the border with Guatemala.
Altitude: <500m

---

lateral view

---

Looks like Sciomyzidae

---

Hi Paul,
Thanks for pointing out the family. It is a large family, so I guess for neotropical species it is difficult to be more specific with just a photo to rely on.
Regards,
David

---

An answer from Lloyd Knutson:

---

Then we revert back to Lauxaniidae.

---

I see a preapical on the fore tibia. I think Lauxaniidae. I think I see an inclinate pair of fronto-orbital bristles. At least Neogriphoneura and Camptoprosopella have that character, but they lack eye bands. I don't have time this morning to check what else lives in Mexico.

---

Start here, quoting the description from Curran (Bulletin of the American Museum of Natural History 80(3):51-84 1942):

Physegenua ferruginea Schiner
SCHINER, 1868, Novara, p. 277.
Ferruginous, the front with three black spots, mesonotum with two or four obscure, narrow, darker vittae; mesopleura with a subrectangular, opaque black spot below the bristle; apical abdominal segnment with median black spot; anterior tibiae and tarsi, an incomplete preapical band on the front femora and the posterior tibiae blackish, the middle tibiae mostly brownish.
A series of both sexes from Brazil.
It is possible that more than one species will agree with the original description.
The opaque black spot on the pleura usually partly surrounds the bristle, and usually only the dorsocentral vittae are distinct. They are rarely brownish.

---

Hi John,
Thanks for your reply.
Curran’s description of Physegenua ferruginea does not seem to mention the banded eyes (at least not included in the part you quoted)?
David

---

Descriptions of Lauxaniidae often omit mention of eye bands. If you want a definitive answer, you'll need to contact Steve Gaimari or another expert.

---

Glad you contacted me to take a look at this! It got me looking at some Physegenua. At first glance, I likely would have called this Physegenua ferruginea too, partly since it lacks markings on the face. But after looking at a bunch of specimens identified as P. ferruginea there is a strange thing I noticed. First, the type - it has mostly clear wings (only darkened along the costa) and the legs aren't nearly so dark. Looking at series of specimens, it seems the ones identified as this species from Mexico have very dark wings and very dark legs, as in the one you photographed. So, I took a look at the literature. After the description of P. urina (Giglio-Tos, 1893), Williston (1894) said that P. urina is very likely the same as P. ferruginea. I think that this idea was followed afterwards, although Giglio-Tos (1895) pointed out that he believed that to be incorrect. One of the differences is that P. urina has very dark wings. I have not seen the type of P. urina, but I believe your fly is that species, which is described from Mexico. I think I need to see this type.

---

Hello Steve,

Thank you very much for your response and for your help in identifying this intriguing species.

Best regards,
David