Philiris diana is a species of butterflies of the family Lycaenidae from Wet Tropics of northeastern Queensland of Australia, commonly known as large moonbeam.

Like in other six members of the group, the hindwing underside of P. diana does not have a black spot on the inner margin, and the male genitalia possess long and asymmetric valvae.

Waterhouse and Lyell illustrated a male and a female from the series, described a new species Philiris diana in 1914, but did not designate any type specimens.

[4] This was invalid, because the holotype of Peters, though incorrectly established, should be treated as the lectotype, and the rest of the series as paralectotypes (13 specimens).

In April 1972 N Qu, N and K. Tindale caught a female in the rainforest near Lake Tinaroo at the Atherton Tableland (750 m asl) and deposited it in the South Australian Museum, Adelaide.

The latter was identified as Philiris diana, though the females of the species were considerably variable in the wing upperside coloration.

The same year the butterfly larvae were collected on brown bolly gum near Beatrice by E. Petrie and R. Mayo, and reared to adulthood.

[2] Philiris diana is divided into two subspecies:[2] Males, upperside: ground color paler violet-blue; costa and apical areas of hindwing broadly white; black terminal band narrower than in P. p. fortuna; forewing with central patch, extending below CuA2; forewing termen weekly arched.

[2] Males, upperside: ground color from intensive cobalt-blue to purplish-blue; costa and apical areas of hindwing grey; black terminal band broader than in P. p. diana; forewing without white central patch or with occasional grey, greyish-white scales, not extending below CuA2; forewing termen strongly arched.

Females, upperside: darker than P. p. diana; forewing central patch small, 20-35% of wing; hindwing costa and apical areas between Rs and M1 and adjacent central area distal to discocellular veins between M1 and M3 reduced, grey, with occasional white scales.