species freshwater crab endemic true freshwater crab country lives streams archipelago high islands abundant little known biology habitat decline quality endangered currently listed concern iucn red list described species later split genus closest relatives species currently found published explain reached isolated location including submerged land bridges ancient means transport open ocean considered likely explanation adults dark yellow brown colour width claws unequal size differs number characters including lengths legs antennae fact species flattened legs compared description truly freshwater crab true crabs islands marine larvae common freshwater crabs large eggs seen eggs diameter described large adult specimens reach width millimetres length width flat rounded outline closest relative surface rough scattered divided distinct regions series grooves raised ridge runs interrupted groove centre grooves colour described dark yellow brown anterior antennae minute smaller claws unequal size distinctly flattened walking legs normal overall concluded differs respects species likely taxonomic history described species genus specific epithet commemorates collected specimens unaware description described paper published proceedings description based specimens donated travelled time species genus coast second species added species time considered sufficiently distinct crabs warrant placement separate subfamily family revised family concluded accommodated species genus family described new genus species took current placed family leaving genus family restricting distribution african mainland following number phylogenetic studies reduced taxon subfamily larger family considered distribution endemic high islands inner group western indian_ocean found largest islands silhouette lives mountain streams flow closest relatives species african mainland shape segment argue close relationship indian crabs family appear reliable phylogenetic character presence strictly freshwater species hard explain possible explanations proposed prior development plate proposed land bridges connected land masses suggested ancestors lived comprising african mainland separated continental drift believed split million years ago separating indian plate million years ago ancient origin supported absence freshwater crabs oceanic islands area mauritius finally ancestor travelled western indian_ocean time larger lower sea levels greater extent explain species found separate islands time divergence estimated independently million years ago million years ago reported tolerant salt water families freshwater crabs allowed survive african continent recent research trans oceanic dispersal uncertainty remains conservation status criteria assessed assessed lack information remaining criterion measures species geographic range species qualify endangered decline habitat quality abundant places present protected area listed concern
Seychellum