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Hi

I'm currently using the Key "Chironomidae of the Holarctic region. Keys and diagnoses. Part 3. Adult Males" by Wiederholm to identify Chironominae.

And I'm struggling with two of the following steps in the key:

" 32. Apex of fore tibia truncate with at most shallow scale lacking spur -> 33
Apex of fore tibia with well-developed scale and/or spur -> 35 "

and

"35. Apex of fore tibia with black spur similar to those on mid and hind tibia. Pars ventralis present. ->Pseudochironomus
Apex of fore tibia without spure but with scale, often bearing spine. Pars ventralis absent -> 36"

I'm not sure how a "shallow" scale is locking compared to a "well-developed" scale or how a well-developed spur looks like.


So if someone has any pictures or figures that would be really helpful!


I have attached a photo of what I believe to be a well developed scale but as I said I am unsure.

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No spur. Pseudochironomus also has a low leg ratio and widely spaced eyes.

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Paratendipes

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Chironomus

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Thank you for the fast reply!

Is this a shallow scale and does Tendipes refer to Microtendipes here?

Since Chironomus branches off before step 32 in my key, I don't know if they have a developed or shallow scale.

Would you identify my photo as shallow scale?

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From which guide did you get the picture?
Because to me it also looks like a scale with a spine but in the book, I use it explicitly lists in step 35 a black spur as a criterion for Pseudochironomus.
So that's why I'm a little bit confused.

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My guess is shallow, but that is subjective and I am unsure.

Tendipes is an old name for Chironomus. The dispute over the correct name lasted from 1908 to 1963 and was resolved only by a formal decision of the International Commission on Zoological Nomenclature. Search on "Meigen 1800 names" for the full history.

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The illustrations come from

Townes, H. K. Jr. 1945. The Nearctic species of Tendipedini [Diptera, Tendipedidae (= Chironomidae)]. American Midland Naturalist 34:1–206

They were reprinted in 1952 in

Guide to the Insects of Connecticut, Part VI. The Diptera or True Flies of Connecticut, Fifth Fascicle: Midges and Gnats.

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John do you know when it comes to Polypedilum if all of the species have a fringed Squama? In the illustrations I have the wing is showing a fringed one.

Because then I could use this trait (+others) instead of the scale (which is vaguer to me) to identify the genera that are important to me.

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I use the shape of tergite 8 to distinguish Polypedilum from other Chironomini.

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It would be more anteriorly tapered compared to other Chironomini right?

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Right.