The type species of Pseudopsila Johnson, P. fallax (Loew), and two related species are found to belong in Psila s. str., and Pseudopsila is thus synonymized with Psila Meigen. The remaining species formerly included in Pseudopsila form a monophyletic group here described as Xenopsila Buck subgen. n. [i.e., Psila (Xenopsila) collaris Loew comb. n., P. (X.) bivittata Loew comb. n., P. (X.) lateralis Loew comb. n., P. (X.) arbustorum Shatalkin comb. n., P. (X.) nemoralis Shatalkin comb. n., P. (X.) tetrachaeta (Shatalkin) comb. n., P. (X.) maculipennis (Frey) comb. n., P. (X.) nigricollis (Frey) comb. n., P. (X.) nigrohumera (Wang & Yang) comb. n.]. A key to the Nearctic species of Xenopsila and the Psila fallax-group is provided. The placement of Xenopsila in Psila s. l. is confirmed by newly recognised synapomorphies of the egg stage. The somewhat questionable monophyly of Psila s. l. is confirmed based on these new synapomorphies, thereby slightly expanding its taxonomic limits to also include Asiopsila Shatalkin. The morphology of the male genitalia of Xenopsila is discussed in detail, clarifying confused homologies and character polarities in the hypandrial complex. Evolutionary trends in the development of the hypandrium in the subfamily Psilinae are discussed.
The male genitalia of the fritillary butterfly Issoria lathonia (L.) were examined and reconstructed based on sagittal and horizontal sections. Nine intrinsic muscles were identified consistent with previous results. The retractor of the anal tube probably operates the "rectal plate", a large, sclerotised, arched plate present ventral to the rectum and dorsal to the phallus in all Issoria s. str. species. The function of the rectal plate is still largely unknown, but it has presumably an important function during copulation. The retractor of the phallus inserts on the phallus, and also on a small, ventral sclerite in the anellus. The retractor of the vesica is smaller in I. lathonia than its counterpart in other Argynnini and originates more centrally inside the phallus. The tergal sclerite, common in most Argynnini, has no attaching muscle and its evolutionary origin remains unclear. The presence of an intrinsic muscle (i3) originating on the tegumen and inserting on the valve in Argynnini cannot be confirmed here. Though generally absent in butterflies, this muscle has been reported once in the North American Argynnis subgenus Speyeria.