Described on the basis of a single mandible (lower jaw) with the first molar missing and an isolated upper incisor, both of uncertain but Quaternary age, it is one of the smaller members of the genus Megalomys.

Little is known about the animal, and its provenance and distinction from "Ekbletomys hypenemus", an even larger extinct oryzomyine that also occurred on Barbuda, have been called into question.

In 1926, Arthur Hopwood finally described it and named it Megalomys audreyae after Gregory's wife Audrey, following Major's intention.

In a 1999 review of recent extinctions in mammals, Ross MacPhee and C. Flemming reported that M. audreyae had been recovered from a locality on Barbuda known as Darby Sink, which had been radiocarbon dated to around 1200 BCE.

[8] However, in 2009 Samuel Turvey suggested that two different rice rats were in fact present in material from Barbuda, which would imply that M. audreyae is a valid species.

The second molar is about square and shows the four main cusps commonly present in rodents: the protoconid, metaconid, hypoconid, and entoconid.

[13] When Clayton Ray described "Ekbletomys hypenemus" on the basis of abundant skeletal remains from both Barbuda and Antigua, he carefully distinguished it from M. audreyae, the only other native rodent recorded from those islands.