Squatina

Walsh, Jonathan H. & Ebert, David A., 2007, A review of the systematics of western North Pacific angel sharks, genus Squatina, with redescriptions of Squatina formosa, S. japonica, and S. nebulosa (Chondrichthyes: Squatiniformes, Squatinidae), Zootaxa 1551, pp. 31-47 : 46

Key to Western North Pacific Squatina Species

1. Pelvic fin tips do not extend to origin of first dorsal fin..............................................................................2.

— Pelvic fin tips extend to or surpass origin of first dorsal fin........................................................................3.

2. A prominent row of thorn-like denticles extending from mid-back to caudal peduncle; no distinct ocelli on posterior lobes of the pectoral fins ................................................................................................ S. japonica

— No row of thorn-like denticles extending from the mid-back to the caudal peduncle, distinct paired ocelli on the posterior lobes of the pectoral fins ......................................................................... S. tergocellatoides

3. Upper lip arch semi-circular in shape (>1.5% TL in height); dorsals are lobed with a curvilinear anterior margin; pelvic girdle distance 1.4 times or less head length; caudal fin is lobed, especially dorsally, with a curvilinear postventral caudal margin ........................................................................................... S. formosa

— Upper lip arch is not semi-circular in shape (<1.5% TL in height); dorsals are not lobed (angular) without a curvilinear anterior margin (straight); pelvic girdle distance greater than 1.4 times head length; caudal fin is not lobed (angular), especially dorsally, without a curvilinear postventral caudal margin (straight) ... ..................................................................................................................................................... S. nebulosa