Thread subject: :: Chironomidae v Ceratopogonidae

Posted by Susan R Walter on 17-11-2022 16:54

I recently received this query from a young French entomologist, translated by me, and since nematocera aren't really my thing I wondered if someone on the forum could help: 'In the case of nematocerans, with neither anal veins joining the wing margin, nor disc cells, nor ocelli, and with a reduced number of veins (no more than 8), the key often leads me to choose between Chironomidae and Ceratopogonidae, without either choice being fully convincing. Also, I regularly find myself at this stage, with very different individuals, not necessarily showing the distinctive antennae for these two families...'

Posted by John Carr on 17-11-2022 19:45

If the postnotum has a longitudinal groove, it is Chironomidae. This is rarely absent and you are unlikely to collect the exceptions in central France. On marine shores you may find them.

If vein M is forked or there is a crossvein between the branches of the radial vein, it is Ceratopogonidae. The veins can be hard to make out in photographs.

If the front basitarsus is longer than the front tibia it is Chironominae. There is a slight amount of overlap in "leg ratio" with Orthocladiinae.

If the last 4-5 antennal segments are elongated, it is Ceratopogonidae. If only the last 1 or 2 are, Chironomidae. If the antenna is reduced to 9 or fewer flagellomeres, Chironomidae.

If the claws are long, a femur greatly swollen, or there are spines under the fifth tarsomeres, one of the predatory Ceratopogoninae. Likewise if it has apparently functional mandibles (in Europe).

Usually if the hind legs are long you have Ceratopogonidae, but see also Tanypus in the Chironomidae.

Posted by Susan R Walter on 18-11-2022 11:17

Thanks John, that looks super helpful. I will pass it on to Anastasia.