Curculionichthys coxipone can be diagnosed from all congeners by having 29-30 vertebrae (vs. 28 in all other congeners). It is distinguished from all congeners, except Curculionichthys sabaji and C. paresi by having the cleithrum with an area free of odontodes (vs. cleithrum completely covered with odon¬todes). It further differs from all other species of Curculionichthys with the exception of C. oliveirai by having the anterior profile of the head rounded (vs. pointed); from C. piracanjuba, C. sagarana, and C. oliveirai by having lower lip with some papillae arranged in a medial longitudinal series extending posterior to dentaries through middle portion of lower lip (vs. lower lip with all papillae randomly distributed); from C. insperatus and C. oliveirai by having the caudal fin hyaline, with one dark stripe extending from the caudal peduncle base to the middle caudal fin rays, and dark chromatophores irregularly distributed almost forming one band (vs. caudal fin hyaline, with dark blotch limited to caudal peduncle base); from C. paresi by the absence of contrasting dark-brown geometric spots on the anterior region of the body (vs. presence of dark-brown geometric spots); from C. sabaji by the absence of several dark-brown spots distributed on the body (vs. presence of dark-brown spots); from C. oliveirai and C. coxipone by having the anterior profile of the head pointed (vs. rounded); from C. oliveirai by having 7?9 lateral abdomen plates (vs. 4?5 lateral abdomen plates); from C. paresi by having 9-13 dentary teeth (vs. 4?7); from C. oliveirai by having 6?9 lateral abdomen plates (vs. 4?5); from C. sagarana by absence of one unpaired platelets on dorsal portion of caudal peduncle (vs. presence of one unpaired platelets on dorsal portion of caudal peduncle); from C. piracanjuba by having some papillae on the lower lip arranged in a medial longitudinal series extending posterior to the dentaries through the middle portion of lower lip (vs. lower lip with all papillae randomly distributed) and by not having hypertrophied odontodes on the snout tip (vs. hypertrophied odontodes on the snout tip); from C. insperatus by having small, inconspicuous odontodes forming rows on the head and trunk (vs. large, conspicuous odontodes forming rows on the head and the trunk). In addition, Curculionichthys coxipone is distinguished by the possession of the following characters: interorbital distance 33.8?37.8% of HL ( vs. 27.4?33.6% of HL in C. sagarana); dorsal fin spine 14.9?24.8% of SL (vs. 25.2?27.0% of SL in C. paresi); pectoral fin spine 19.0?25.2% of SL (vs. 27.0?30.1% of SL in C. paresi); mandibular ramus 8.2?12.5% of HL (vs. 6.0?8.0% of HL in C. paresi); and snout length 48.0?58.9% of HL (vs. 67.7?72.7% of HL in C. piracanjuba; 67.0?75.3% of HL in C. luteofrenatus) (Ref. 113800).

Description: Dorsal fin ii,7; anal fin i, 5; pectoral fin i,6; Pelvic fin i,5 (Ref. 113800).