Pseudosiobla campbelli is an extinct species of sawfly in the family Tenthredinidae that is known from early Eocene Ypresian stage[1] lake deposits near the unincorporated community of Horsefly, British Columbia.

[2] The species is known from only the holotype, a single, mostly complete adult female, now deposited in the Geological Survey of Canada collections as specimen number "GSC No.

[2] Rice published his 1968 type description for P. campbelli in the Geological Survey of Canada professional paper number 67-59.

The single known female possesses a head, thorax and posterior segments of the abdomen which are dark brown to black.

by several features: P. campbelli is notably larger than members of Eriocampa and the wing vein patterning is distinct.