1. According to < Morphological and Molecular Evidence for a Stepwise Terrestrial Evolution and Species Delimitation on the Coenobita Phylogeny >, it suggested that Coeonbita hilgendorfi Terao, 1913 is the heterotypic synonym of Coneobita brevimanus. They could be apparently distinguished by the difference in the left cheliped:
A. Left cheliped longer than broad in outline, outer surface hardly smooth in any part, but covered with quite small tubercles → Coenobita hilgendorfi (Armored Indo)
B. Left cheliped nearly circular in outline, outer surface very convex and nearly smooth → Coenobita brevimanus (Indo)
Coenobita hilgendorfi only appear in male and some individuals changed their sex from male to female after moulting.
The relationship between their sex and morphology is worth of paying more attention in the future. When it comes to the analytical results of species delimitation, Hung (2008) suggest that Coenobita hilgendorfi and Coenobita brevimanus are the same species, and that the morphological type of Coenobita hilgendorfi only appears in the male individuals.