FIGURE 4 in Taxonomic status of Akodon oenos (Rodentia, Sigmodontinae), an obscure species from West Central Argentina

FIGURE 4. Details of the alisphenoid region in skulls of Akodon oenos and A. spegazzinii showing the posterior ascending process of the alisphenoid bone between the squamosal and the bulla. Specimens: a. CNP 1897 (A. oenos, Llancanelo Natural Reserve, Mendoza), b. CNP 2352 (A. oenos, topotype; La Pega, Mendoza), c. CNP 1493 (A. spegazzinii, Las Chacritas, Catamarca), and d. CNP 1491 (A. spegazzinii, Carapunco, Tucumán). Abbreviations: al = alisphenoid, ap = ascending process, as = alisphenoid strut, bmt = buccinator-masticatory through, bu = auditory bulla, fo = foramen ovale, pg = postglenoid foramen, sag = squamosal-alisphenoid groove, sq = squamosal, tt = tegmen tympani, za = zygomatic arch.