Pettibone doesn't appear to state an etymology for Grubeulepis, perhaps regarding it as self-obvious (although there are no etymologies in the entire work, which is unusual for Pettibone). It is probably named as remembrance for Grube's role in the family history, because Eulepis Grube, 1875, the type genus of the family, was replaced by Eulepethus for reasons of junior homonymy.
Pettibone, M.H. (1969). Revision of the aphroditoid polychaetes of the family Eulepethidae Chamberlin (=Eulepidinae Darboux; =Pareulepidae Hartman). Smithsonian Contributions to Zoology. 41: 1-44. available online athttp://si-pddr.si.edu/dspace/handle/10088/5690