Trichomycterus dali is readily distinguished from epigean and hypogean congeners by the presence of two conspicuous, ridge-like adipose folds lining dorsally throughout the body, one anterior (pre-dorsal) and one posterior (post-dorsal) to the dorsal fin, both distinctive autapomorphies in the genus. Other characters that easily distinguish the new species, although not exclusive, are: highly reduced skin pigmentation (except for T. gorgona and caverestricted congeners, T. chaberti, T. itacarambiensis, T. spelaeus, T. sandovali, T. santanderensisand T. uisae); total loss of eyes, not visible externally (except for T. sandovali and T. spelaeus); barbels long, especially the nasal (99.3- 143.5% HL) and the maxillary (97.0-131.3% HL) (except for T. longibarbatus and T. spelaeus); scapulocoracoid with a conspicuous anterior process projected forward (except for T. sandovali, T. spelaeus and T. uisae), with a narrow base, a wide apex and a rounded distal margin; and pectoral-fin ray count reaching I,9 (except for T. hualco). Characters possibly exclusive, but about which many taxa lack information, are listed as complementary diagnoses: cranial fontanel unique, extending from the posterior half of supraoccipital to the posterior region of the frontal bones, with a conspicuous constriction on the meeting point of supraoccipital and the two frontal bones; supraorbital long and cylindrical, without projections, with a needle appearance; 27-29 interopercular and 16-19 opercular odontodes (Ref. 87887).