Unlike in the type species of the genus, N. albigularis, the lacrimal bone of the skull is connected primarily to the maxillary bone, not equally to the maxillary and frontal bones. The incisive foramina, perforations in the palate between the incisors and the molars, are shorter than in some other Nephelomys species, not extending between the molars, and closer to the molars they are wider than further to the front, also unlike in some other species of the genus.[4] These foramina are similar in shape to those in N. nimbosus.[6] The alisphenoid strut, an extension of the alisphenoid bone of the skull which separates two openings in the skull, the buccinator–masticatory foramen and the accessory oval foramen, is usually present, although it is more commonly absent in other Nephelomys.[4]