comb. form of L. āter black, as in atrorubent reddish-black, atrosanguineous of a dark blood-red color.
1697. Luwyd, in Phil. Trans., XXVII. 467. All black, or atrorubent.
1833. M. J. Berkeley, Glean. Brit. Algæ, 6. Purple Chætophora.… Frond thin, effused, atrosanguineous.
1887. Syd. Soc. Lex., Atrosanguineous.
