M. hjorti was originally described from five badly damaged specimens from the North Atlantic, then redescribed by Rancurel (1973) from three squid from the Gulf of Guinea. The species is distinctive and widely distributed but uncertainty exists on the taxonomic status of populations in other oceans.

Brief diagnosis:

A Mastigoteuthis ...

• with two photophores on each eyeball.
• with very large fins (length ca 90% of ML).