Taningia

Taningia is a genus of squid, one of the two referred to as octopus squid, the other being Octopoteuthis, its sister genus. Both Octopoteuthis and Taningia are characterized by their lack of tentacles for the majority of their life cycle, which led to their common name.

Classification

This genus is named after Danish fisheries biologist Åge Vedel Tåning.
Taningia is separated from Octopoteuthis by adults possessing a large photophore on the tips of arm pair II, which are the only known photophores on the body along with the ink sac organ. The photophores, around the size of lemons, possesses eyelid-like skin flaps which conceal the light organs when needed. The genus reaches in mantle length, though has also been reported. This genus possesses two rows of arm hooks on each arm pair, which develop after ML; a single photophore may also develop on the ink sac at this size. The paralarvae have robust tentacular stalks; these disappear at ML, leaving the squid with eight arms.
Additional diagnostic characters include arms being 25-58% of ML, with arm pair II being the shortest, each arm having a single broad buccal connective, and the mantle cartilage being broad, and blunt towards the head.
Traditionally, this genus is considered to be monotypic, with only Taningia danae as a valid species. T. persica was named from a paralarval specimen in 1923, and it is currently considered a species inquirenda synonymous with T. danae due to the uncertain identity of the holotype, and is ruled by the International Code of Zoological Nomenclature in 1994 that T. danae should be given precedence over T. persica after a 1992 petition. A 2019 thesis recovered more species in this genus, but these are nomina nuda and have not yet been accepted by various online taxonomic databases.
The two accepted species in the genus includes the following:

Taningia danae, Dana octopus squid: holotype from Atlantic, semi-cosmopolitan
Taningia silasii, Indian Octopus Squid: holotype from the southeastern Arabian Sea