Butterfly Morphology Question

[Deleted]

Hey Guys,

This is something I've been wondering for a long time, what the heck are these "flaps" called and what are they used for? They are hinged and easily move up and down. Google has failed me once again.

[saye]

Do they move up and down, or can you move them up and down? Also, that's a Papilio species correct? I've never heard of any sensory organs in that locale, which would then mean the "flaps" are regular chaetae with an ornamental twist. I'm curious towards other replies.

[Adam Cotton]

These are called tegulae (singular: tegula) and they cover the thorax at the base of the forewings. Their purpose is not exactly clear, but it is likely for protection of the joint with the wing.

Adam.

[saye]

How curious. Never noticed them. Are they family-specific?

[Deleted]

Thank you very much Adam, you never cease to amaze me with your knowledge. After learning what they are called I was able to find a little more info, they are for streamlining the body, and as Adam said, insulation/protection of the wing base. Butterflies of America has a great page about morphology and other terms related to Lepidoptera if anybody is curious: butterfliesofamerica.com/glossary.htm

I'm not sure if they are able to move independent of force/exertion Saye, this is something I will certainly investigate in the spring. I have noticed them on many butterflies, so not family specific, although I can certainly see the possibility for use in ornamental/mating behavior in some species. It could be a very interesting topic for study.

The specimen from the picture is indeed a Papilio species, but let's see if anybody can guess

[eurytides]

In a previous post, you mentioned that a Rhyssonotus nebulosus flew into your home. These are native to Australia, where ther are no indigenous tiger swallowtails. Therefore, the tiger swallowtail you have is imported. It's difficult to say from the small field of view picture, but I would hazard a guess of Papilio rutulus or Papilio canadensis.

[exoticimports]

OK I'll play- glaucus from New England USA, probably from the more northern part of the range.

[eurytides]

I wondered about that, but the black anal margin band seems too thick in the picture for glaucus. That's why I included canadensis. Some hybrids and spring brood glaucus could look like that I suppose.

[Adam Cotton]

This could also be Papilio alexanor but it is very difficult to be sure from the small area visible.

Adam.

[eurytides]

Okay, I think we're ready to hear the official answer....or at least a picture that's got a larger field of view!

[Deleted]

I wish I were in Australia! It would be much warmer than my current location, you are thinking of Raymond.

But anyways, drum roll please....and the answer is-Papilio rutulus collected in northern Idaho

[eurytides]

Ah, sorry I mistook you for someone else!! If I had known your location I would've been more confident with rutulus, which was still my primary consideration. So, are there prizes to be handed out???

[Deleted]

I am feeling generous from the holiday season, but to be fair to other members, perhaps I will start doing a forum contest to spice things up a little bit. You ID with most accurate locality, you win the specimen including free shipping. One week to play and a new contest every month

[irisscientist]

I quote Kristensen (Handbook of Zoology, Lepidoptera, Moth and Butterflies Vol2) regarding this subject matter:

"The tegula is a hollow integuental outgrowth which arises with a narrow membranous 'stalk' above the anterior forewing base and curves around the latter. Tegulae are modestly sized in the ground plan state, as inferred from conditions in Micropterigdae and Agathiphaga, but they are larger in Trichoptera and Mecoptera. While their development in Ditrysia is homoplasious they may not be very prominent in higher lineages, and particularly their posterior part, extending backwards over the wing base, can be markedly elongated. The outer tegula wall is more or less strongly sclerotised and has a vestiture of lamellar and/or piliform scales, which may be distinctively coloured. The inner wall is naked and membranous; the plesiomorphic position of the stalk aperture is near-central, or at least clearly above the ventral margin; is is retained in most Lepidoptera, but a position adjacent to the margin is prevalent in butterflies. Tegular innervation is suggestive of mechanoreception (proprioception?), but its precise role is unknown; in some Pyralidae-Galleriinae the tegulae are stridulatory organs. Tegular diversity was reviewed by Hering (1958); for additional information see Minet (1991)."

As Adam correctly states, their function is unclear, but their nerve innovation would suggest some wing movement sensory function. The distinct colouration in some species could also suggest some function during courtship.

Hering (1958): Die Tegula der Lepidoptera, ihre Funktion und taxonomische Verwertbarkeit
Minet (1991): Tentative reconstruction of the ditrysian phylogeny (Lepidoptera: Glossata)

booksandjournals.brillonline.com/content/journals/10.1163/187631291x00327?crawler=true

Not much more to add here really, but hope it is of some use?


Mark

[Deleted]

Thank you for sharing the info Mark. There were a lot of words I had to look up from the quote, but certainly have a better understanding of entomology through the process.

The possibility of their use for courtship is very intriguing, and could have easily went unnoticed by entomologists of the past. Now we have reasonably priced cameras with high enough frame rates to study the phenomena, if it does occur. I could see them being used for territorial behavior as well.