Syrphid Fly - Ceriana - BugGuide.Net

I've been thinking the best placement here may be C. ancoralis

In various ways this appears intermediate between C. tridens and C. ancoralis...but overall it seems closer to the latter.

In particular, affinities to ancoralis are: 1) it appears to lack any yellow on the pteropleura; 2) the yellow hind edge of the vertex is long & narrow, and 3) the supra-alar vittae appear quite weak here (if they're even present?)...and ancoralis typically has less pronounced supra-alar vittae than tridens...e.g. see the thumbnail below:

It's conceivable variation may allow for the virtual absence of the supra-alar vittae in ancoralis.

On the other hand, the medial black break in the yellow of the hind edge of the vertex seems a bit wide for ancoralis (cf. couplet 4 in Curran's key), and the yellow posterior band of the 4th tergite is quite wide medially...though it smoothly tapers in width (rather than being somewhat uniformly wide in the middle, and then tapering more sharply nearer to the lateral edges as is more typical of tridens).

A frontal view of the face could help ascertain the ID in a case like this (since the upper part of the overall black marking there is appreciably more widely bell-shaped in tridens than in ancoralis)...but the tangential view of the face here makes that character hard to assess.

The records of ancoralis in Coquillett(1891), Curran(1924), and Shannon(1925), as well as the paratype here...are all from New Mexico. And my reference post here is only a mile or two into AZ from the New Mexico border. However the range given on the Systema Dipterorum C. ancoralis page is "Arizona to Texas"; while the range given in on the Systema Dipterorum C. tridens page is "Washington to Idaho, s. to California".

At any rate, C. abbreviata (and similarly, C. mime) can be ruled out by the 2nd abdominal segment here...which is as long (or longer?) than the 3rd. Moreover, that pair of difficult-to-separate Ceriana species has a more "eastern" range; whereas C. ancoralis and C. tridens are the "western" difficult-to-separate species ;-).

[PS: I can see how a skeptic may want to throw in the hat and promote lumping ancoralis under tridens; and (even more so), mime under abbreviata.]

… Aaron Schusteff, 25 June, 2021 - 4:45pm

Undescribed sp. or C. cacica

This is likely an undescribed species. Although it could be C. cacica if the anepimeron is yellow, but I can't tell. If it is black it is probably undescribed. Unfortunately, I don't have a specimen of C. cacica for comparison.

See the 4th tergite. The posterior yellow band is HUGE, bulging outwards medially and also reaching the posterolateral corners. The spot in C. mime is much smaller and does not reach the posterolateral corners. Additionally, the posterior band on tergite two is not noticeably thinner in the middle and wider in the posterolateral corners.

It lacks supar alar vittae which means it is not C. ancoralis. Additionally, it has a pair of spots above the anepisternum which means it's not C. abbreviata.

… Kevin Moran, 29 October, 2018 - 2:00pm

I think Ceriana cacica can be eliminated here

A dorsal illustration of C. cacica appears in volume 2 of the Manual of Central American Diptera(1) (and a much larger and clearer (color!) rendition appears at this Flickr link). The illustration suggests the absence of pale posterior bands on T3 and T4. This seems a bit incongruous with Walker's original 1860 description of C. cacica, which states:

"abdomen with a whitish band on the hind border of the first, second and third segments; band of the third segment very narrow"
But the true 1st segment has no posterior band here or in the MCAD drawing...it seems Walker mistook the true 1st and 2nd abdominal segments as a single "1st segment" there. Either way, the wide posterior band on the 4th segment here wouldn't appear to fit C. cacica.

PS: Kevin, I'm wondering about the anepimeron being yellow in C. cacica? That's not mentioned in Walker's description. Is there another more detailed description you've found? Or have you seen specimens of C. cacica? (It would be great if someone were able to make good diagnostic images of that species available on the web!)

… Aaron Schusteff, 25 June, 2021 - 4:09pm

Undescribed sp?

Kevin,

Thanks for your comments. This is, indeed, exciting if it is an undescribed species. I'm not sure what the anepimeron is. Unfortunately, I don't have any shots that show the fly in profile. I was able to get only three shots before it flew away. I've added another photo but fear it may not show more than the first one.

Loren Padelford
Bellevue, NE

… Loren & Babs Padelford, 1 November, 2018 - 12:31pm

Anepimeron = Pteropleuron

Loren & Babs, I can empathize with the difficulty of diciphering the various terms associated with all the little sclerites of the thorax!

According to the glossary here, the "anepimeron" is the plate below the wing base...which has also gone by the name of "pteropleuron". I've illustrated the pteropleuron in previous posts...see "ptp" in the labelled image here, and/or the sclerite labelled "pteropleuron" under the wing in the full-size version on the post below:

In your post here, I think yellow on the anepimeron/pteropleuron would be somewhat visible if it were present (despite the non-optimal oblique viewing angle in the two photos). If I zoom in on your photos (by repeatedly pressing "cntl-+" on the keyboard while viewing in my web browser window) I believe I do see yellow on the "sternopleuron" (labelled "sp" in the thumbnail image above, and also known as the "katepistermun")...although it's a nearly tangential view!

… Aaron Schusteff, 25 June, 2021 - 4:23pm

Moved

Moved from Ceriana mime.

… Kevin Moran, 29 October, 2018 - 1:50pm

Moved

Moved from Flies.

… Martin Hauser, 25 March, 2018 - 4:39pm

Ceriana mime

Dr. Hauser,

Thanks, so much, for confirmation of Bill Dean's ID. Finding a rare fly like this one is really exciting.

Loren and Babs Padelford
Bellevue, NE

… Loren & Babs Padelford, 25 March, 2018 - 11:13pm

Indeed, this is very exciting

Indeed, this is very exciting... I have never seen this species in the wild! So I envy you for being able to take pictures..... Great job!
Martin

… Martin Hauser, 25 March, 2018 - 11:15pm

Ceriana mime

Ceriana mime.
I have sent it to Martin for his opinion.

… Bill Dean, 25 March, 2018 - 4:14pm

Ceriana mime

Bill,

Thanks for your help! This is an exciting, and apparently somewhat rare, find.

Loren and Babs Padelford
Bellevue, NE

… Loren & Babs Padelford, 25 March, 2018 - 11:10pm