In the British Isles the genus Conwentzia is represented by two species:

Conwentzia pineticola and Conwentzia psociformis

Both species have the following features:

Conwentzia features. AACV (crossvein between veins A1 and A2), CCCV (crossvein between Cu1 and Cu2). Image: Rintala and Lehto (CC BY-4.0)

To differentiate between the two species you need to examine the male genitalia. Prior to this you need to clear the abdomen to be able to view the structures clearly.

Below shows the features of the two species, the structure of the parameres and the ectoprocts viewed looking at the tip of the abdomen.

The defining features of the two species of Conwentzia. Images: C. pineticola Rintala and Lehto (CC By-4.0), C. psociformis Rintala and Lehto (CC By-4.0), CBG Photography Group (CC BY-3.0), Zhao et al. 2021 (CC BY-4.0)