E. longirostris is one of six crane fly species in the genus Elephantomyia described from the Baltic amber, the others being E. baltica, E. bozenae, E. brevipalpa, E. irinae, and E.

The fossils were reexamined and the species redescribed in 2015 by paleoentomologist Iwona Kania of the University of Rzeszów, who examined the holotype and the ten additional specimens.

Kania noted that two of the specimens Loew had placed into the species did not match the type description or redescription well, each having a notably short rostrom.

The rostrum has elongated palpus at the tip, each composed of four segments and having a system of microtrichia hairs.

The fifteen segmented antennae are small, composed of an elongated scape, widened pedicle and thirteen flagellomeres.