Borrodaile describes two variants of this species, as follows:
"i. var. typica, Alcock, III. p. 222.
Dark-brown specimens. Taken on the reef at Goidu, Goifurfehendu Atoll.
ii. Var. formosa Smith, 1869. {Proc Bost. Soc. N. H. Xil. p. 286.)
This variety differs so sharply from the dark-brown true digitalis that it seems to deserve a separate varietal name. In structure the variety is like digitalis, but it somewhat resembles T. J-erruginea in the shape of the front. This feature, however, varies considerably in digitalis. The earliest name for the orange-coloured form is formosa Smith. T. corallina Gerstaecker,
1856, is a coral-red crab."
(Borrodaile 1903)
