Holt and Tattersall, 1905
Generic diagnosis:
The eye is round.
Thoracic legs 1-6 are similarly developed. The 7th pair of thoracic legs is distinctly developed, but the endopod consists of only two elongated joints. The 6th and 7th thoracic legs have an exopod in both sexes. Only the 8th pair of thoracic legs is rudimentary (Meganyctiphanes-thoracic legs). Both the terminal and the proximal processes of the petasma are developed.
The front margin of the carapace is without any rostral process, but with well developed post-ocular spines on the carapace.
The petasma has the same processes as the species of the genus Thysanopoda, but, also, as many as four small additional processes on the median lobe.
The eggs of Meganyctiphanes are shed before hatching.
The genus is monospecific.