Hello, I have recently discovered within my axolotl tank that there is a strange aquatic isopod....

[spiderlover123]

The habitus is definitely different from Asellota and Cymothoidea (the typical freshwater isopods) and, in fact, is consistent with that of Porcellio scaber and Trachelipus rathkii (the photo doesn't help me to separate between those two options)! Its seemingly longer and more slender body, which could favor the Asellota option, is just an artifact of the photo (taken from the outside of the cup/bottle). The ''gills'' are in fact the pleopods, which have retained the gill-like structure of their ancestors, but now contain a system of ''false lungs'' for breathing on land.

Although a small number of terrestrial isopods have returned to a semi-aquatic lifestyle (check here), no species has become fully aquatic again and will usually drown after some time underwater. Concerning the latter two candidates (P. scaber and T. rathkii), they aren't even considered amphibious (although, as mentioned before, because of T. rathkii's wet habitat, he is more tolerant of freshwater), so it is remarkable that this specimen remained underwater and even successfully gave birth! By the way, when did you first notice its presence in the tank and are there any climbable surfaces-rocks, semi-aquatic plants, filtration gear etc, that stand above water? Also, did you @spiderlover123 keep the female after death? A good photo of the body out of the water could help put a proper name on it.

Some other interesting things that I noticed: a) She was ''HUGE'' (and maybe this character helped her survive a bit more underwater?)! I have seen and collected female Porcellio obsoletus that easily reach 3 cm (ca. 1.20 inches), but I have never found literature records of this magnitude for P. scaber and T. rathkii! b) In the photo, the posterior half of the body (5th tergite and downwards) is paler. This usually corresponds with freshly molted specimens. So, if it isn't another artifact of the photo, it means that she had molted very recently, perhaps less than an hour before the photo was taken!

Indeed! You have hit the head of the nail with your statement. I do in fact still have the body and do intend to preserve it as a wet specimen. And she was in fact in the middle of a molt!

 

[ShrekFeces]

Fantastic news! It seems the isopod has colonized the tank! spiderlover123 has claimed there is another specimen with the same appearance and behavior in the tank! So hope is not lost! We are waiting in anticipation to see if this means there are more in the tank, and if so this could be great news!

Do you have a picture?

 

[gothmoth]

This is a really fascinating thread. I hope you guys @spiderlover123 , @IdentifyThisPod1556 continue to post updates! Never kept isopods and have absolutely no experience with axos or really any water-dwelling species to be honest, but I'm totally enthralled with this little future colony of isopods!