Thank you for all your help. The reason I thought this might be Mesosa longipennis is I found a photo exactly the same naming it and saying it was from Japan. Now I have found your site I will be more careful. Regards Lenny
In all likelihood, it is an Agelasta of the subgenus Dissosira. Unfortunately, Yamasako et Obayashi recently revised this group and transferred several Mesosa-species here. Consequently, it is very difficult to reconstruct a key.