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Photo#822069
Arizona mantispid - Dicromantispa sayi

Arizona mantispid - Dicromantispa sayi
Florida Canyon Station, Santa Rita Experimental Range, Pima County, Arizona, USA
July 25, 2013
Size: Head to wingtips: 20 mm

[Note: Full-size image can be seen here.]


Found at a mercury vapor light on the first night of the summer 2013 BugGuide gathering in AZ. I'd been wanting to see one of these amazing creatures for years!! The last two images of this series show the specimen on a cloth sheet at the lights...the preceding images were taken later on a sheet of paper.

It was fairly straightforward narrowing the ID here down to either Dicromantispa sayi or Leptomantispa pulchella. But how do you distinguish between those two often very similar-looking species...both of which are themselves quite variable, and have distinctively different light and dark forms? Perusing the comments accompanying BugGuide posts for these species will show this question can become a problematic quagmire! I became engrossed in trying to fathom its nuances and understand some of the subtleties involved.

The principal character used to separate the taxa in the Canning brother's 2006 treatment of Mantisipdae of Canada, and Hoffman's 2002 treatment of Mantispidae of Costa Rica, involves the hairs of the "giraffe-like" necks (or pronota) of these mantispids. In L. pulchella there are short setae ("hairs") distributed uniformly along the length of the pronotum, while in D. sayi the setae are finer still and mostly localized at the anterior and posterior ends of the dorsum of the pronotum (or virtually lacking). The Canning brothers also mention that in L. pulchella the (upper surface of the) pronotum is smooth, while in D. sayi it has evident transverse ridges. A problem with these characters is that in many images the magnification/resolution is insufficient to discern the setae. Luckily, one of my images shows the character fairly clearly. (And I was also able to check the setae under a microscope.)

But it turns out that in certain cases you can bypass the subtle pronotal setae character. In particular, if your mantispid has tri-colored antennae...with basal 2/3 brown, next 1/6 yellow, and last 1/6 dark brown...then you have D. sayi! (See couplet 2 in Hoffman's key). That's the case in my post here. The antennae of L. pulchella, on the other hand, are uniformly brown to black...except for the basal segment which is yellowish.

However, it turns out that on many D. sayi specimens, the antennae can be identical to those of L. pulchella,...so the "tri-color antennae" character doesn't always save the day. But then, you might ask, if D. sayi can have uniformly dark antennae, doesn't that contradict Hoffman's main key character for D. sayi ??!!

I believe the answer to that question is no...because Hoffman's key treats Costa Rica, and presumably the form of D. sayi present in Costa Rica has consistently tri-colored antennae. I'm speculating that the tri-colored antennae form ranges from Costa Rica northward into the warmer southern part of the US...which is supported by the (verifiably identified) image data on BugGuide.
[Postscript (8/24/13): I recently obtained Hoffman's excellent dissertation(1), which confirms that "the tricolored antennae occur on specimens from the southern United States southward". The southern range limit given for D. sayi in that work is Panama(1).]

Interestingly, it turns out D. sayi comprises (at least) three different color forms which are largely allopatric (see 2nd paragraph here). Those color forms correspond to three previously named species: Mantispa sayi, M. fuscicornis, and M. uhleri (original descriptions here,  here, and at bottom of pg. 79 here)...all of which were synonymized under D. sayi in Hoffman (1989). The dark forms of D. sayi, from east of the Mississippi River and northward...having much black coloration on the abdomen, pronotum and forelegs (especially in females)...correspond to the former Mantispa uhleri. Lots of interesting life history and other info on M. uhleri (=D. sayi) can be found here. These dark "uhleri" forms of D. sayi can look very much like the the dark forms of L. pulchella...and the light forms of D. sayi (with their dark antennae) can look very much like the light forms of L. pulchella. So what else can be used to tell the two apart ??

Well, in general, L. pulchella is significantly smaller in overall length and size than D. sayi. But precise scale measure is not clear in most images, and besides...adult mantispids within a given species can vary in size by very large amounts, since their final size depends on the size of the spider egg sac the larva parasitizes, and mantispids attack many different spider taxa of many different sizes.

A trick I happened upon (not mentioned explicitly in any references I've found) is to carefully scrutinize the wing venation. The details are a bit cumbersome to describe here, but basically the smaller relative size of L. pulchella translates to fewer cells and veins along the length of the wing than in D. sayi. (In an informal terminology I've adopted, the rubric is: "5 wishbones along the posterior edge of the forewing for pulchella, and 8 wishbones for sayi".) Perhaps I'll write up a forum article with details and diagrams if there's interest. At any rate, I'll just end by encouraging those of you who haven't done so already to read about the fascinating life history, biology, and ecology of these intriguing organisms. Redborg (1998) is an excellent review article. And I'll pose a question: Is this a male or a female? :-)

Images of this individual: tag all
Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi Arizona mantispid - Dicromantispa sayi

great discussion, thanks
Aaron, thanks for these detailed comments. I have been trying to sort these two out, but did not have access to the original keys, nor as keen an understanding as you have. You might want to double-check ID's of images assigned to both species here.
It is especially good to know about the details on the pronotal setae and the antennae.

A couple of additional "field marks" I have noticed for L. pulchella:
-usually shows a wide dark bar across the top of the head--in D. sayi, this bar is usually broken up
-pterostigma usually bright reddish, and the angle at the tip is more acute than in D. sayi.
These are not 100% consistent, especially the last one. Here is a Dicromantispa with a very red pterostigma, for instance:


And, below are images assigned here to D. sayi, but I believe shows more characters of L. pulchella, though the image is not as detailed as one would like:

The second and third ones, in particular, seems to show setae on the "neck" like L. pulchella.

 
Hi Patrick
Your posts of Leptomantispa pulchella from the 2012 gathering in Tennessee are a good part of what prompted me to devote concentrated attention to the goal of understanding characters that can be used to distinguish L. pulchella and Dicromantispa sayi.

It seemed that few people were mentioning (or aware of?) the principal key character used in the main Mantispidae references...namely, the setation on the pronotum described in my remarks above, and illustrated in lateral view in Figs. 607 and 608 on pg. 432 of Hoffman (2002), and in dorsal view in Figs. 582 and 585 on pg. 428 of Hoffman (2002).

Also, it seemed to me that head markings, and the angle of tip of the pterostigma, were too variable and less clear than the setation character. But the setation character is usually too subtle to show up at the magnification and resolution of most BugGuide posts. So what to do?

Happily, I was able to formulate an alternate character that seems to work well, based on the wing venation diagrams in Fig 571 (D. sayi) and Fig 586 (L. pulchella) of Hoffman (2002). I've made a nice labelled JPEG based on Figs. 571 and 586 of Hoffman, clearly illustrating the character, but I don't know if copyright considerations allow me to freely post it on BugGuide.

Suffice it to say that, if you look at those figures at the links above, you'll see that the venation on the distal half of the posterior edges of the forewings has a number 3-segment groupings that look "wishbone-shaped" or equivalently, like "inverted-Y's". Each of these "wishbones" is attached by its "stalk" to a closed cell above it. The number of those wish-bones (and their associated cells above) is 8 in D. sayi, whereas the number is 5 in L. pulchella.

Of course, there is no guarantee given in Hoffman or the other references that the number of these wish-bones is consistent throughout large samples of individuals. And I've often read of (and rarely seen) instances where things like wing venation can vary wildly between individuals of the same taxon (or even left and right wings of the same individual). But usually such occurrences are fairly anomalous. And so I tested the "5 vs. 8" character on as many seemingly "good" ID's as I could find among BugGuide posts, and it seemed to hold true with flying colors. Then I ran into an example of D. sayi that had 9 wish-bones! Well, if there are more than 8 for a putative D. sayi, I'm still happy. And less than 5 for L. pulchella (and maybe even 6 for a robust individual) would still be good to I think. The underlying idea behind the wing venation character is that, on average, D. sayi is a significantly more robust species than L. pulchella, and it's reasonable that that is reflected in more cells and "wish-bones" in their wing venation.

So I think the best way to try to determine the species here is, as usual, to try to employ as many of the characters as you can (pronotal setation, wing venation, color characters, antennal characters, size, and location, etc.), and when they characters consistently cluster in the specified groupings for the taxa, you can be fairly confident in your ID. So far, I've found the wing venation character has excellent agreement with all the other characters when a clear ID is possible, so for now I'm quite happy with it.


Finally, I agree with you that there are currently some misplaced posts on BugGuide under both D. sayi and L. pulchella. I'd agree that the 3 thumbnails you included in your comment above are among them. Below are two currently posted as L. pulchella that look to me be D. sayi:



And here's a post under D. sayi that looks like it should be under D. interrupta:


 
An exception to the "8 wishbones" character for D. sayi
As mentioned above, right after I had became confident that the wing venation of D. sayi might consistently have 8 "wishbones" (from all the posts I had scrutinized up to that point), I encountered one that didn't have 8 wishbones. But it still passes the test, because it has more! See the post below, of what I'd say is a strong example of the "Mantispa uhleri" form of D. sayi:



So there is some variation among individuals in this character. But as long as there are no D. sayi with, say, less than 8 wishbones...and no L. pulchella with, say, more than 6, then I'll be satisfied that a somewhat relaxed "wishbones character" works well to separate the two taxa. And even if there are some anomalies, if...in a large sample...the above character works, I think it will be useful as at least a secondary distinguishing character.

And by the way, I should clarify a detail...in the discussions above I'm only counting the uninterrupted strings of consecutive (i.e. side-by-side) wishbones on the forewings. Both Dicromantispa and Leptomantispa can have one or two tinier wishbones near the apical wing tips which are separated from the "consecutive" wishbones by one or two straight, unforked veins...and I'm not counting those tinier apical wishbones.

 
Great work on venation
Aaron, I just reviewed my several Mantispids based on a remark on an iNaturalist.org upload of mine here. I began scouring through the couple of dozen images of all Mantispids that I'd photographed in Central Texas and independently noted the venation differences between Leptomantispa and Dichromantispa. (None of my images, made with a small point-and-hope Canon camera, have enough resolution to recogize setae on the pronota.) I picked the best of my lateral images and tediously--and carefully--traced over the venation of the FWs to bring out details. I'll be uploading these enhanced images to iNat later (links to follow).

For three examples that I now identify as Leptomantispa pulchella, the "wishbone" counts are 4,5, and 5 (the last with a small adjacent wishbone right at the apex of the FW, not counted).

I have only three clear lateral examples of Dichromantispa, one D. sayi and two D. interrupta, and the counts are 8, 8, and 8. Perfect.

This "extra" venation in Dichromantispa can also be recognized in the crossveins coming off the closed cell which straddles the distal end of the stigma. (The cell and venation terminology of Ephemeroptera is in dire need of standardization!) In Dichromantispa, there are typically 3 sinuous crossveins angling towards the rear off of that cell. In Leptomantispa, these number only 2.

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