A new fossil species of the recently described insect order Mantophasmatodea (Polyneoptera: Anartioptera), the “African rock crawlers”, is described and figured from Eocene (Lutetian) Baltic amber. Adicophasma spinosa, new genus and species, differs from the only other fossil of this lineage, Raptophasma, by the strong spination of the fore- and midlegs, broad abdominal segments, and absence of dorsal carinae on the profemur, resembling in these respects the living African genera Mantophasma and Praedatophasma. The position of the fossil and of the order among polyneopterous insects is briefly discussed.