Have you tried to contact prof. Magda Vincx from Ghent University? Nematodes are one of her specialties. Here's her email,  [email protected]. Good luck.

Do you mean literature sources or specimens? Have you tried the nemys database? (usually a good starting point for lists of species and primary literature)

http://nemys.ugent.be/

Dear Daniel Leduc

I agree with you but the Nemys database is not giving any identifying characteristics of all species of Tricoma, however it is giving only the updated species list. 

Try contacting Wilfrida Decraemer at the Royal Belgian Institute of Natural Sciences, she's the expert on the family, and she has helped me in the past:  [email protected]

Try to contact dr Grazyna Winiszewska Museum & Institute of Zoology PAN. Wilcza 64 Warsaw. mail: [email protected]. She is in position to help You, I hope.  Greetings from Gdynia, Poland.

Thank you very much Andrzej Skwiercz