Glaucostegus

Glaucostegus, also known as giant guitarfishes, is a genus of large Indo-Pacific rays, with a single species, Glaucostegus cemiculus, in the East Atlantic, and Mediterranean. They were formerly classified in the family Rhinobatidae but are now recognized as a distinct family, Glaucostegidae.

Their upperparts are uniform pale yellowish, brownish or greyish, and the nose is pale. Most are large, reaching 1.7-3 m in length depending on the exact species involved, except for the small G. obtusus that is less than 1 m.

Species
There are ten recognized species, all of which are classified as critically endangered:


 * Glaucostegus cemiculus (Geoffroy St. Hilaire, 1817) (Blackchin guitarfish)
 * Glaucostegus granulatus Cuvier, 1829 (Sharpnose guitarfish)
 * Glaucostegus halavi Forsskål, 1775 (Halavi guitarfish)
 * Glaucostegus microphthalmus (Teng, 1959) (Smalleyed guitarfish)
 * Glaucostegus obtusus (Müller & Henle, 1841) (Widenose guitarfish)
 * Glaucostegus petiti (Chabanaud, 1929) (Madagascar guitarfish)
 * Glaucostegus spinosus (Günther, 1870) (Spiny guitarfish)
 * Glaucostegus thouin (Anonymous [Lacépède], 1798) (Clubnose guitarfish/Thouin ray)
 * Glaucostegus typus (E. T. Bennett, 1830) (Giant guitarfish)
 * Glaucostegus younholeei (Habib & Islam, 2021) (Bangladeshi guitarfish)