Bornean moths in the noctuid subfamilies Rivulinae, Phytometrinae, Herminiinae, Hypeninae and Hypenodinae are described. Their status and relationships are discussed in an introductory review of the classification of the Noctuidae and in diagnoses of each group. Definition of the Hypeninae beyond a core group of four genera is weak, though one other generic grouping around Mecistoptera Hampson is recognised. Eight genera are only tenuously associated, and a few are set aside for comparison with the heterogeneous array of taxa in the traditional concept of the Acontiinae.
The treatment covers 340 species distributed over 51 genera. For each species, a diagnosis and the geographical range are given and, where known, details of habitat preference and biology. Summary lists are provided of the new taxa described (6 genera and 144 species) as well as of numerous other taxonomic changes. A checklist of all species summarises the fauna, including 7 species transferred into the groups treated here, but covered in previous parts.