Phytoliriomyza pittosporocaulis is an Australian species of fly in the family Agromyzidae.
Phytoliriomyza pittosporocaulis and the similar-looking P. pittosporophylli both have a pale frons, a lunule approximately in the form of a semicircle, reclinate orbital setulae, a black scutellum, pale halteres, and dorso-central bristles in a 3+1 arrangement. It can be distinguished from P. pittosporophylli by the third antennal segment being largely yellow.
The larva has 4-6 bulbs in each posterior spiracle; this differs from the 8-10 bulbs of P. pittosporophylli.
Full descriptions of the adult and larva (and the gall produced by the latter) were given by Hering.
Larvae of this species form twig galls on sweet pittosporum (Pittosporum undulatum). These galls are up to 5.7 mm in diameter and semi-ovoid or hemispherical in shape. Sometimes multiple galls occur together with overlapping edges.