Petrobia Ewing 1909

Toroitich, Faith J., Ueckermann, Edward A., Theron, Pieter D. & Knapp, Markus, 2009, The tetranychid mites (Acari: Tetranychidae) of Kenya and a redescription of the species Peltanobia erasmusi Meyer (Acari: Tetranychidae) based on males, Zootaxa 2176, pp. 33-47 : 36

Petrobia Ewing 1909 (Bryobiinae: Petrobiini)

It has 3 pairs of prodorsal setae and 10 pairs of opisthosomal setae all borne on prominent tubercles, peritreme ending simply with a bulb-like structure. Empodium curved distally and has two rows of ventrally directed tenent hairs. With 3 pairs of anal and 3 pairs of para-anal setae. Tarsus I has 3 pairs of duplex setae.