New species alert! This brightly coloured wonder was found hiding in plain sight at a market in southern China recently. Not only is it a new species of freshwater crab, but it's also the first of an entirely new genus (that's the taxonomic rank above species).

Crab Main 2016 09 15
Image: Huang et al./Zookeys

A team of researchers including Chao Huang of Sun Yat-sen University in Guangzhou came upon the freshwater crab while surveying an ornamental fish market in Northern Guangdong. Because of their bright hues, freshwater crabs are becoming increasingly popular in the pet trade.

According to a new study describing the species, its maroon-brown carapace (what you might call its "shell"), reddish-purple claws, slender legs and oddly shaped gonopod (a reproductive organ that also acts as a swimming appendage) helped the crab stand out in the crowd. After a double take, the team decided to obtain a DNA sample. Back at the lab, analysis confirmed their hunch: they had indeed stumbled upon a species unknown to science.

This isn't the first time we've seen a new species pop up in a pet market. In fact, everything from flying squirrels to giant lizards has been discovered this way. The trend is troublesome, but in many cases, nothing sinister is at play – fishermen and traders simply don't know what they're handing out, and such markets are often poorly managed. 

The creature's official name, Yuebeipotamon calciatile, is derived from the Chinese "Yue Bei", which translates to Northern Guangdong, where the crab was found. "Calciatile” refers to the stream pools the crabs call home in the wild.

By scouring cracks and crevices in these streams, the team found many more specimens, which helped them paint a clearer picture of this animal's ecology. Those long legs you see give the crab a climbing advantage in its slick, unstable habitat. It also seems that adult crabs are more brightly coloured than the youngsters.

Crab3 2015 09 15
Long legs give the crab a climbing advantage in its slippery habitat. Image: Huang et al./Zookeys
Crab Closeup2
Image: Huang et al./Zookeys
Crab Under 2016 09 15
A view of the crab's underside. Image: Huang et al./Zookeys


Top header image: Huang et al.