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Fly - Ocyptamus - male

Fly - Ocyptamus - Male
Santa Ana National Wildlife Refuge, Hidalgo County, Texas, USA
November 24, 2007


Ocyptamus dimidiatus
I looked at determined specimens of Ocyptamus cylindricus and Ocyptamus dimidiatus. This is not Ocyptamus cylindricus which is very similar to Ocyptamus fuscipennis but has a completely metallic abodomen. O. cylindricus is only currently known from Jamaica, Hispaniola, Puerto Rico and the Virgin Isl. This is actually Ocyptamus dimidiatus.

Gil made the identification,
Gil made the identification, and he revised the group recently for his PhD, so I would be careful.... I do not have my material here, Gil had it and I think right now it is "parked" at the Smithsonian...

Ocyptamus dimidiatus
I looked at the NMNH material which were specimens identified by Dr. Thompson. Identification for both species was in 2003. Dr. Thompson should be in today or Tomorrow and I can ask him.

Edit: Actually he identified my specimen of O. dimidiatus last year.

cylindricus group
It is definitely from the Ocyptamus cylindricus group (= sensu stricto), and Kevin is right about the abdomen being different in O. cylindricus (it needs to be more slender than the one on the picture). But from all the O. dimidiatus (and O. antiphates which is close to it)that I've seen, none had this bluish/purplish metallic shine (which is something noted for O. cylindricus). I saw some like those in Costa Rica as well but didn't go further in my studies on that. So that was why I avoided naming it as so... The cylindricus group is completely manageable and could use a revision (specially to sort out O. antiphates and O. dimidiatus which, in the end, I think it is the same thing), and then we could be more confident in setting a name on this one :)

Sorry for the confusion there... there are more than 300 spp. in the genus, I do hope to make the rest of Ocyptamus sensu lato more manageable!

In field experience
Hi Gil,

Thanks for your response. I have a field observation that might help. I have caught several specimens of these in Florida. When alive they have the vibrant blue color you see here. However after death over a period of 24 hours they slowly change to a dark purple/black metallic color which is what you see in pinned specimens.

After death...
Thanks for the info, Kevin! Strange that the ones that I have are all a dull dark brown, no metallic shine... the pale areas on the specimens vary a lot too. Something to take into account in a future review.

Antiphates + dimidiatus
I looked at my personal specimens of dimidiatus and antiphates out of curiosity and found a few characters to distinguish them. This is certainly not comprehensive however as I only looked at 3 and 2 specimens respectively. Might be of use for a future revison though.

O. dimidiatus: ventral scutellar fringe absent; black femora; face with medial black vittae; frontal triangle completely black; scutellum black.

O. antiphates: ventral scutellar fringe present; yellow femora; face completely yellow; Frontal triangle only black medially; scutellum yellow with at most small black area medially.

Thompson 1981
Hi Kevin,

Those look like the ideal extremes to separate them! And your ids look fine! But I have seen a range of variation between these two extremes (with dark areas expanding/receding, indistinct medial vitta on the face), incomplete ventral fringes on the scutellum and combination of these different characters, but all this working mainly with south american material. I have yet to get a larger series of genitalia dissections to see if the differences carry on there.

Dr. Thompson, in his 1981 paper on the flower flies of the west indies, offers more characters to separate the two species... but again, I've seen overlap. I've seen another picture here in bugguide where there are some metallic reflections on the specimen's abdomen, but at the same time the pale areas on the abdomen were also visible (not possible in the 1981's diagnoses).

Locality Info.
What is interesting is that these two extremes were caught at the same locality on the same day. I also caught O. cubanus and O. parvicornis there as well. This magical place may or may not have been my Parents' backyard. They were all collected visiting rhododendron, azalea to be specific, which apparently they go nuts over.

Everytime I visit I always see O. antiphates, O. dimidiatus and O. cubanus. I only saw O. parvicornis once. So if your wanting DNA I can assist you and I'll see if I can't catch some when I visit over Thanksgiving.

Alternatively I have an extra males of both extremes.

Thanks everyone for the great
Thanks everyone for the great dialogue on this one!!


Moved from Ocyptamus.

Moved from Syrphid Flies.

Difficult, but I think this is a species of Ocyptamus, but a species of which there are no pictures in the guide yet!

Moved from Flies.

Wing venation is that of a syrphid, though one I've never seen before. Beauty, eh?

Beauty, agreed
Metallic color and smokey wings make a spectacular combination.

Ocyptamus cylindricus
Hi folks, Gil Miranda (a student of mine and the world expert on Ocyptamus) has identified this as Ocyptamus cylindricus - new for the guide.

What a fabulous photo! I intend to use it in a talk that I am giving in Scotland next week when I discuss Gil's research. I will give full credit to Tom in my talk of course.


Sounds good Jeff. Are you wi
Sounds good Jeff. Are you willing to help me sort out some other Syrphid ids?

Certainly, I am happy to help but I am travelling for the next few weeks so I won't have much time. You can contact me directly at if you wish.


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