Among the
Noctuoidea, the Erebidae can be broadly defined by the wing characteristics of the adults with support from phylogenetic studies. The cubital forewing vein, which runs outward from the base of a wing to the
outer margin, splits into two (bifid), three (trifid), or four (quadrifid) veins from the
medial area to the outer margin. These split veins are named M2, M3, CuA1, and CuA2 in order toward the
inner margin. A trifid forewing has either a reduced or vestigial M2 vein or the M2 vein does not connect to the cubital veins, while M2 is as thick as M3 and connects or nearly connects to M3 in a quadrifid forewing. The same splitting of the hindwing cubital vein has analogous terms bifine, trifine, and quadrifine. The Erebidae typically have quadrifid forewings and quadrifine hindwings, though the
Micronoctuini are exceptional with their bifine hindwings. Among the related families, most Erebidae are quadrifid moths like the
Euteliidae,
Nolidae, and
Noctuidae and unlike the trifid
Oenosandridae and
Notodontidae. And among the quadrifid moths, the Erebidae have quadrifine hindwings like the typical
Nolidae and
Euteliidae and unlike the typical
Noctuidae.
Phylogenetic studies in the present century have helped to clarify the relationships between the structurally diverse lineages within the
Noctuoidea and within the Erebidae. Morphological studies had led to a classification in which the monophyletic
Arctiinae,
Lymantriinae, and
Micronoctuini were treated as families, and the other erebid lineages were largely grouped within the
Noctuidae. Recent studies combining genetic characteristics with the morphological ones revealed that the former Noctuidae were
paraphyletic, and some of the lineages within the Noctuidae were more closely related to the
Arctiinae and
Lymantriinae subfamilies and the
Micronoctuini tribe than to the other lineages within the Noctuidae. The determination of these phylogenetic relationships has led to the present classification scheme in which several clades were rearranged while kept mostly intact and others were split apart. The Erebidae are one
monophyletic family among six in the
Noctuoidea. A more strictly defined family
Noctuidae is also monophyletic, but the family lacks the quadrifine moths now placed as part of the Erebidae. Some subfamilies of the Noctuidae, such as the
Herminiinae, were moved as a whole to Erebidae. Other subfamilies, including the
Acontiinae and
Calpinae, were each split apart. The
Arctiinae became an erebid subfamily placed next to the closely related
Herminiinae. The
Lymantriinae became another erebid subfamily placed near the
Pangraptinae. The rank of the
Micronoctuini was changed from family to tribe to include the clade as a lineage within the
Hypenodinae. The Erebidae are currently divided into 18 subfamilies, some of which are strongly supported by phylogenetic analysis and may persist through further study, while others are weakly supported and may be redefined again. == References ==