Promynoglenes grandis is a species of sheet weaver spider endemic to New Zealand.
This species was described in 1979 by A.D Blest from male and female specimens. The holotype is stored in the New Zealand Arthropod Collection under registration number NZAC03014984.
The male is recorded at 3.83mm in length whereas the female is 3.42mm. This species has a dark brown cephalothorax and yellow legs with black markings.
This species is known from the South Island of New Zealand.
Under the New Zealand Threat Classification System, this species is listed as "Not Threatened".