Notoscopelus kroyeri dorsal fin has 21 or 22 soft rays, the anal fin has 18 to 20 soft rays and the pectoral fins have 12 to 13. Like other members of the genus, it has many small photophores on the sides and flanks of the fish, arranged in a fashion that is characteristic to this species. Mature males have a gland consisting of eight or nine luminous scale-like segments on the dorsal surface of the caudal peduncle, but they lack the bioluminescent patches on the cheek and above the eye that are characteristic of some members of the genus. "N. kroyeri" is
Largetooth cookiecutter shark and sparsely scattered light-emitting photophores on the belly. Most specimens have lacked the dark "collar" found on the throat of "I. brasiliensis". However, a specimen caught in 2004 off the Azores did possess the collar. The maximum recorded length is . Based on its smaller dorsal and caudal fins, the largetooth cookiecutter shark is believed to be less active than "I. brasiliensis" and an overall weak swimmer. Much of its body cavity is occupied by an enormous oil-filled liver, which allows it to maintain neutral buoyancy in the water column with little effort. Unlike "I. brasiliensis", this shark possesses binocular