iNat's policy is to follow WoRMs for Crab (Brachyura) taxonomy. They adopted changes proposed in http://web.nchu.edu.tw/~htshih/acad/pdf/Shih&2016_Ocypodidae_revision_s.pdf to split Uca into two groups Broad-fronted and Indo-west Pacific Fiddler Crabs (Subfamily Gelasiminae) and American Narrow-fronted and East Atlantic Fiddler Crabs (Subfamily Ucinae). I wrote this blog post to try to alleviate some of the confusion these taxonomic changes have sown https://www.inaturalist.org/projects/fiddler-crabs/journal/17610-fiddler-crab-taxonomy