Abstract
The Pacific collections by the MUSORSTOM campaigns of the Museum national d'Histoire naturelle, Prais, over the last 20 years have included a number of Tanaidacea from waters of the New Caledonia region. The species described herein as Mekon solidomala, from 440 and 700m depth, represents a new tanaid genus and species of the subfamily Langitanainae of the family Tanaidae. While displaying the ventrally fused pleonites four and five and the four-segmented antennule characteristic of the subfamily, it is distinct from the two previously known genera in having a non-flagelliform, four-segmented uropod, massive mandibles, and a large, subspherical carapace, the posterodorsal part of which overlaps the first and most of the second pereonite. One tanaid paratype bore a copepod parasite representing a new genus and species of the family Nicothoidae, Arhizorhina mekonicola. This new genus appears most closely related to Rhizorhina in its extreme reduction of body segmentation and tagmosis, and in the total loss of limbs; however, it lacks the branching rootlet system that is diagnostic for Rhizorhina, and the stalk is configured differently
