Fletcher & Nye (1982) stated:-
Scudder, 1875, Proc. Am. Acad. Arts Sci. 10: 135, mistakenly treated Castnius Hübner, , as a homonym of Castnia Fabricius, 1807.
Hemming, 1967, Bull. Br. Mus. nat. Hist. (Ent.) Suppl. 9: 98, treated Castnius as an unjustified emendation of Castnia, but there is no evidence to support that conclusion; none of the three nominal species included in Castnia by Fabricius was included in Castnius by Hübner. In this catalogue we have followed Evans, 1937, ibidem: 15, and Oiticica, 1955, Revta bras. Ent. 3: 144, and treated Castnius Hübner, , as a distinct genus.
P. pelasgus is dated from the wrapper of part 17, not from the title-page of volume 3 which is dated 1782.
Learn more about Castniidae in Wikipedia