Posterior end of maxilla expanded dorsally, truncate or slightly concave; supramaxilla terminally positioned.
Mouth large, upper jaw very long, extending beyond edge of operculum in both sexes as a flexible scimitar-shaped lamina; maxilla reaches pectoral-fin base only in male holotype (0.9 in HL; in female 1.1 in HL; in juvenile 1.5 in HL); supramaxilla present, narrow and anteriorly positioned.
The maxilla is moderate (1.5 in HL.) and pointed posteriorly with a concave subterminal margin dorsally, a convex subterminal margin ventrally; supramaxilla large and subterminally positioned.
Upper jaw sexually dimorphic: upper jaw length of 27 adult males (66.2-94.2 mm) 30.0-34.3% SL, 19 adult females (61.2-92.4 mm) 23.1-27.8% SL; end of maxilla expanded and subterminally rounded, becoming elongate and scimitar-shaped in males, nearly reaching opercular margin; supramaxilla narrow and positioned about midmaxilla.
fossoris-galapagensis in having a rigid maxilla that is not sexually dimorphic or dichromic and in lacking a supramaxilla, it is the only Atlantic species that has the subopercle broadly expanded distally and multifid nasal cirrus in adults.