(Fig. 11)
Synonyms. None.
Type host and locality. Pentoceros richardsoni, south Pacific Ocean.
Morphology. Size: 80–90 mm. Papillae: partial coverage, generally spherical, variable in size and shape, not found in organized groups. Holdfasts: three, two laterals short; dorsal horn shorter. First antenna with four segments, second with two segments. Plumes: dendritic, complex branching.
Remarks. A valid species. Well described, figured and discussed in the original report. An intermediate size Pennella species parasitic on a unique host, the pelagic armourhead (boarfish), P. richardsoni. Kazachenko and Kurochkin (1974) documented several specimens of the adult female and younger pre-adult individuals in metamorphosis. Pennella hawaiiensis resembles P. filosa but is a smaller parasite; it also superficially resembles and is close in size to P. remorae, but has a different cephalothoracic papillae configuration, has one less segment on the first antenna, and parasitizes a much different type of host. Pennella hawaiiensis is the only species of Pennella other than P. exocoeti (a smaller parasite which does not possess a dorsal holdfast horn and is found on flyingfish) which exhibits a four-segmented first antenna.