I NEED HELP FROM ISOPODS PROS

Lately i bought springtails and this little dude was inside with them!!!

I have no idea what to do now. My isopods are armadillidium and while i am not super sure, i think this dude doesnt look like he is too. What do i do? Could i put him in enclosure with the rest of my guys? I dont really want to buy more of his specific species, i dont think i have enough experience to buy even more isopods, but at the same time i dont think i can just let him go in my garden! I dont want to introduce alien species.

What to do? I feel like keeping him all alone is kinda bad but i dont know what else i could do.