bowelfly: gachimushi: thesumlax: birdsbugsa…

bowelfly:

gachimushi:

thesumlax:

birdsbugsandbones:

bowelfly:

MAD MAD MAD

A friend asked what was going on with the mouthparts here so I sketched this up:

What we’re seeing (mostly) is not the mandibles, but splaying of the clypeus and labrum, and the paired maxillae. It looks super weird because the dragonfly is upside down – nice grab by @bowelfly too, this is textbook How To Hold Your Dragon(fly).

The maxillae move out and down, and they can splay open but they aren’t here. The mandibles (or at least what I’m 99% sure are the mandibles) are visible but they’re not open until the last picture:

Uhhh… no? Actual mandibles are probably bigger, and definitely not jointed. Those are most likely the big black appendages right under the labrum, while the tiny limbs are maxillae, and the bottom cover is labium (it is basiclly a second pair of maxillae fused together, but still). 

Insect mouthparts awlays follow the same simple scheme, even if some parts are drastically modified or lost entirely:

labrum (upper lip, simple unjointed flap);

mandibles (paired, unjointed upper jaws);

maxillae (paired, jointed lower jaws that bear palps);

labium (lower lip; like I said, it`s a second pair of maxillae fused itogether);

– you can also count hypopharynx if you want (the closest thing they have to a tongue, not sure if it`s the thing visible in this dragonfly`s mouth).

This will probably help clear things up.

fr-frons, pclp-post clypeus, aclp-anteclypeus, lbr-labrum, md-mandible, mx-maxilla, lbm-labium.

Diagram from Borror and Delong’s Introduction to the Study of Insects, 7th Edition

hello everyone and welcome to

ODONATE ANATOMY DISCOURSE HOUR

anyway yeah as @gachimushi points out, @thesumlax is correct:

image

That’s the maxillae in red and labium in green.

image

The mandibles are not very obvious in the photo, but I think that’s them on either side of the clypeus/labrum “upper lip.” not circled.