This bat was described from central Vietnam in 2013. The paper covers records from central Vietnam and adjacent Laos, and the current MDD lists Myotis annatessae as a valid species.
In the 2013 description, the type-series bats had gray-brown fur above, a paler underside, and short body hair.
At the Song Con River in Vu Quang, bats in the type series were observed flying about 1–7 m above the water and foraging over ripples and backwaters.
An extinction-risk assessment has not been added yet.