Leptogium sphaerosporum is a species of corticolous (bark-dwelling), foliose lichen in the family Collemataceae.

The type specimen was collected on the track from Thulo Syabru to Bamboo (Langtang) at an elevation of 1,970 m (6,460 ft).

Here, in a shady and humid mixed broad-leaved forest, it was found growing on the bark of Alnus nepalensis.

The apothecia are up to 1.5 mm (0.06 in) in diameter with a flat brown disc and a thallus margin that is pale blue.

The ascospores are spheroid, muriform (divided into chambers) with rounded tips and have dimensions of 19–27 by 14–19 μm.