[4] Akodon spegazzinii was first described in 1897 from Salta Province by Oldfield Thomas on the basis of a collection made in late 1896 or early 1897 by mycologist Carlos Luigi Spegazzini, after whom the species was named.
[5] Four years later, Joel Asaph Allen named Akodon tucumanensis from Tucumán Province, comparing it to various species now synonymized under Abrothrix olivaceus.
[6] Thomas named an additional species, Akodon alterus, from La Rioja Province in 1919, and considered it closely related to A. spegazzinii.
A 1992 paper suggested that alterus and tucumanensis were, at best, very similar to each other,[10] but in 1997, Michael Mares and colleagues listed each of the three as distinct species in a compendium of the mammals of Catamarca, citing differences in habitat and fur coloration.
[12] In 2000 Díaz and colleagues listed alterus and tucumanensis as subspecies of spegazzinii in a review of the mammals of Salta.
The specific name, oenos, is Greek for "wine" and refers to the animal's occurrence in the wine-producing region of Mendoza.
In 2010, Pablo Jayat and colleagues reviewed the members of the Akodon boliviensis species group, including A. spegazzinii, in Argentina.
They could not find clear differentiation in either morphological or molecular characters between animals belonging to A. alterus, A. leucolimnaeus, A. spegazzinii, and A. tucumanensis, and consequently concluded that they all represent a single species.
[10] Although genetic variation is relatively high within A. spegazzinii, there is no clear geographic structure among haplotypes from different regions.
[21] The next year, Ulyses Pardiñas and colleagues concluded that A. oenos, which had formerly, and incorrectly, been placed in the A. varius species group, was in fact another synonym of A. spegazzinii.
[23] The boliviensis group is part of the highly diverse genus Akodon and thereby of the tribe Akodontini, which includes about 90 species of South American rodents.
Akodontini is one of several tribes within the subfamily Sigmodontinae and the family Cricetidae, which includes hundreds of mainly small rodents distributed chiefly in Eurasia and the Americas.
[21] The formerly recognized species Akodon tucumanensis corresponds to the dark, low-altitude populations, while A. leucolimnaeus and A. alterus represent more reddish, high-altitude animals.
The opening behind the palate, the mesopterygoid fossa, is of intermediate width,[22] being narrower than in A. sylvanus, A. simulator, and A. budini but broader than in A. caenosus.
[37] Akodon spegazzinii is found in northwestern Argentina, in the provinces of Salta, Catamarca, Tucumán, La Rioja, and Mendoza, at altitudes of 400 to 3,500 m (1,300 to 11,500 ft).
[40] Akodon spegazzinii is known from a paleontological site in Tucumán Province dated to the latest Pleistocene (Lujanian); it is among the most common species there.
[42] At one locality in Mendoza, Akodon spegazzinii occurs at an estimated density of 21 individuals per hectare (8.5 per acre) and has a home range size of about 300 m2 (3200 sq ft).
[43] A number of sigmodontines have been recorded as occurring with A. spegazzinii, including A. caenosus, A. simulator, Neotomys ebriosus, Abrothrix illuteus, Reithrodon auritus, Andinomys edax, and various species of Eligmodontia, Necromys, Calomys, Oligoryzomys, Oxymycterus, and Phyllotis.