Petrelaea dana, the dingy lineblue,[1][2] is a species of lycaenid butterfly found in Indomalayan realm.

Hindwing: in addition costal and dorsal margins narrowly paler and duller in colour; termen not furnished with a tail at apex of vein 2.

Forewing: two pairs of short, slender, transverse white strigae, the inner pair from costa to median vein across middle of cell, the outer pair from costa along each side of the discocellulars stopping short at lower apex of cell; a transverse, discal, bisinuate, catenulated (chain-like) narrow band formed of a double series of slender white lunules followed by an inner and outer subterminal series of transversely elongate spots enclosed in or bordered on the inner and outer sides by obscure slender whitish lunules; lastly, a dark brown anteciliary line.

[3][4] Female upperside: costa and termen very widely, dorsum very narrowly brownish, darkest on the apex; middle two-thirds of the wing from base white with iridescent blue scales; a transverse dark discocellular spot but no anteciliary dark lines.

[3] Kumaon to Sikkim; Bhutan; Bengal; southern India: Nilgiris, Cochin; Chittagong; Upper and Lower Burma; Tenasserim; Sri Lanka.