We have recently found a species of crayfish in a branch of the Portage River (Northwest Ohio, USA) with which we are currently unfamiliar- does anyone know what species this is? (Pictures attached)
Hello,
Front view, can you see a ridge/carina in the rostrum? if not it could pertain to Cambaridae; on the contrary, Astacidae or Parastacidae. Orconectes limosus (alien species in Europe) has the sides of rostrum almost parallel or slightly convergent. I think that is a good genus identification character but I am not sure if other species pertaining Orconectes genus show this character.
Hey there Sarah,
I'm no expert on NW Ohio crayfish, but this looks much like the Calico Crayfish, Orconectes immunis (Hagen). From Taylor and Schuster (2004), if the dorsal surfaces of the fingers of the chelae possess longitudinal ridges (I think I can faintly see them in the picture) then that would be a pretty definitive character to separate it from O. limosus, O. compressus or O. parmeri. Here's a picture of a Calico Crayfish for reference: https://www.inaturalist.org/observations/841011
That's my vote on the id for what it's worth!
Based on your suggestions (and a crayfish of Ontario guide sent from a colleague) I am fairly confident the species we found is O. immunis. The males we caught had curved copulatory stylets and all of the individuals had a very distinct notch midway down the chelae... thank you for your time and assistance!
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