[2] Two poorly described, unresolved taxa are known only from planktonic hatchlings (Macrotritopus equivocus and M. scorpio), and a further three undescribed Indo-Pacific species may be attributable to this genus.

[3] The genus Macrotritopus was described by Grimpe (1922) for the single planktonic specimen of Octopus gracilis Verill, 1884, the name referring to the very long third arm pair on the paralarvae.

[2] Given that O. gracilis Verill, 1884 was a junior homonym of O. gracilis Souleyet, 1852,[4] authors Joubin & Robson (1929) replaced it with Octopus (Macrotritopus) equivocus, with Macrotritopus regarded as a subgenus at that time, these authors also described M. danae[2].

The presence of "Macrotritopus larvae" off South Africa and the Indo‑West Pacific from Australia to Hawaii indicates that there may be a number of yet to be described species within this genus.

from the SW Atlantic (possibly M. beatrixi) has recently shown that the genus groups very closely with Thaumoctopus mimicus and Wunderpus photogenicus, which are also long-armed species living in shallow sandy environments.