Morphological comparisons. Comparison of diastemal and palate region in four species of Thomasomys. A T. otavalo sp. nov. (MECN 6912, holotype); B T. ucucha (MECN 7937); C T. igor sp. nov. (MECN 702, holotype); D T. silvestris (MECN 4928). Arrow in (A) indicates that the anterior border of the M1 at the same level of the posterior end of the zygomatic plate; the lower dotted line indicates the penetration of the mesopterygoid fossa in relation to the hypoflexus of the M3; abbreviations: hf, hypoflexid; if, incisive foramina; mpf, mesopterygoid fossa; pal, palate; ppp, posterolateral palatal pit; zp, zygomatic plate. Scale bar: 5 mm.