A new monotypic genus, Mcphersonarcys is erected to hold Pentatoma aequalis Say, a species formerly placed in the genus Hymenarcys. Based on the distribution of 19 character-states Hymenarcys forms a clade with its sister genus Coenus. Both genera are related to the large genus Euschistus. Mcphersonarcys is basal to Euschistus, whereas the clade with Hymenarcys and Coenus is derived. Removal of P. aequalis to a new genus resolves the paraphyly of Hymenarcys sensu lato.
Thomas, Donald B.
"Mcphersonarcys, a New Genus for Pentatoma Aequalis Say (Heteroptera: Pentatomidae),"
The Great Lakes Entomologist, vol 45
Available at: https://scholar.valpo.edu/tgle/vol45/iss2/3