I'll be happy to provide taxonomic information as well as the biology of the freshwater isopod.
I have some identification keys that are very basic to clearly distinguish them with the help of a pair of microscopes.
I attached a link where you can see the key to Williams (1970) A revision of North American epigean species of Asellus. On pages 4-17 is the description of the species Caecidotea communis (most common in North America). I recommend paying attention to pages 8 and 11 as the palm of the second pleopod gnatopod are heavier characters in taxonomic identification.
This is the link to download the key
To differentiate between males and females is easy. Pay attention to the palms of the gnatopod, it´s presence is a sexual dimorphism in males. Because this gnatopod is much larger in males (Figure A on page 8, first pereiopod).
Crepuscular, it would very kind of you could help me. I just need at least 20 specimens. Would it be possible to send me these specimens?
Thank you all!