Notogynaphallia fortuita is a species of land planarian belonging to the subfamily Geoplaninae.

The base color of the dorsum is beige, with scattered dark spots all across.

Along a thin line of the body, these spots are less dense, forming an ill-defined pale stripe running along the dorsum.

[2] The specific epithet is derived from the Latin fortuitus, meaning "casual, by chance"; this is due to the fact that only a single type specimen of N. fortuita was found after several searches of the area.

[2] Notogynaphallia fortuita is only known from a type specimen found on Isla Paulino, in Berisso, Argentina.