This species is distinguished from all species of Spectracanthicus by its color pattern consisting of a dark gray body, without dots or spots, and by having very slender teeth (vs. with small to mid-sized yellowish dots in S. punctatissimus, S. murinus, and S. tocantinensis; and large white spots in S. zuanoni. This can be further differentiated from S. punctatissimus and S. zuanoni by having pointed snout in dorsal view (vs. snout rounded). Additional characters useful to separate this species from other congeners include the following: nasal quadrangular (vs. nasal L-shaped); posterior margin of pterotic-supracleithrum without contact with posterior margin of orbit (vs. with large contact with orbit in S. murinus and small contact in remaining species); cartilage area of basipterygia short (vs. elongate in remaining species, except in S. murinus); anterior fenestrae of cartilage area of basipterygia large in size (vs. small to median size in remaining species, except in S. tocantinensis) (Ref. 95496).

Description: Dorsal-fin rays i,7; anal-fin rays i,4; pelvic-fin rays i,5; dorsal-fin base very long, its length equivalent to 12 dorsal plates, reaching pre-adipose plate and connected to adipose fin by thick membrane; dorsal-fin spinelet V-shaped with locking mechanism (Ref. 95496).