Dorsal soft rays (total): 11
3.7 cm SL (male/unsexed; (Ref. 75063)); 3.69 cm SL (female)
Distinguished from most other members of the genus Odontostilbe by having a remarkably long anal-fin base 26.0-33.5% SL, with only Odontostilbe nareuda has a similarly long anal-fin base length 31.3-32.8% SL, but can be differentiated from Odontostilbe pulchra in having anal-fin rays 24-26 (vs. 17-24, usually 19-22 in Odontostilbe pulchra). In addition, mature males of Odontostilbe pulchra differ from Odontostilbe fugitiva, Odontostilbe ecuadorensis, Odontostilbe dierythrura, Odontostilbe parecis, Odontostilbe paraguayensis, Odontostilbe microcephala, Odontostilbe splendida, and Odontostilbe pao by possessing hooks on the 1st to 22nd anal-fin branched rays of males, practicallyon all branched anal-fin rays (vs. 1st to 9th, mostly 6th-7th, anal-fin branched rays of males with hooks); distal border of anal fin slightly concave to almost straight in mature males (vs. distal border concave); longer pectoral fin passing a vertical through pelvic-fin origin (vs. shorter pectoral fin reaching but not trespassing to vertical through pelvic-fin origin), almost absence of elongation of the 2nd unbranched dorsal-fin ray (vs. noticeably elongate 2nd unbranched dorsal-fin ray). Furthermore, males, females and unsexed specimens differ from Odontostilbe fugitiva by having longer upper jaw 26.8-32.5% HL (vs. 23.4-30.0% HL). The snout length in males separates Odontostilbe pulchra (18.0-26.0% HL, mean 21.8%) from the sympatric species Odontostilbe splendida with 24.1-26.9% HL, mean 25.2% HL, and Odontostilbe pao with 26.7-30.6 HL, mean 28.6% HL (Ref. 75063).Description: Dorsal fin ii9; Anal fin iv, v, or vi, 17, 18, 19, 20, 21, 22, 23 or 24; Pectoral fin i10, 11 or 12; Pelvic fin i6, 6i; 7, or 7i. Precaudal vertebrae, including Weberian apparatus 14, 15 or 16 (Ref. 75063).