Spontaneous lore dump:

The human-amphibian mutant species known as the "Salamen" (cuz salamander, riiight?) are the result of illegal experimentation with alien technology, which found its way onto Earth's surface via a traffic accident between an alien research vessel and the ungodly amounts of debris (don't litter, kids!) in Earth's orbit.

After countless expeditions into terraformed areas caused by the alien ship's scattered remains and unknown substances oozing out of them, certain biological material has since been recovered. This "bioslush" was found to have numerous uses in medicine and bioengineering.

However, some eeeeeevil scientists got hold of a few samples and through the spectacular combination of human test subjects, axolotl/salamander DNA and a dose of nerd insanity, created these guys.

Not long after, the scientists (still evil) were eventually discovered by authorities, and thus the new species was set free to live amongst humans as an another intelligent life-form. Salamen were found to be excellent colleagues and assistants to humans, thanks to their remarkable dexterity and brain...ness, in place for being smaller and weaker.

I guess I'm a writer now, huh...