Hemming (1967) stated:-
There has been some confusion regarding the species to be accepted as the type-species of this genus, partly because of a misconception as to the work in which the name Hemiargus was first published and partly because of faulty identifications of the nominal species selected as type-species.
The first author to deal with this question was Scudder (1875, Proc. amer. Acad. Arts Sci., Boston 10 : 186) who fell into the twofold error of supposing that the name Hemiargus was first published in the Verzeichniss and of assigning the date "1816" to the portion of that work in which that name appeared (Verz. bekannt. Schmett. (5) : (69). In actual fact, as is now known, this portion of the Verzeichniss was not published until 1819, that is, one year after the publication of volume 1 of the Zuträge, in which also the name Hemiargus appeared.
From the species placed in Hemiargus in the Verzeichniss Scudder selected Papilio hanno Stoll,  (Aanhangs. Weak Uitl. Kapellen Pieter Cramer : 170, pl. 39, fig. 2) to be the type-species of Hemiargus. That nominal species was not included in Hemiargus when that genus was originally established in the Zuträge and accordingly its selection by Scudder as the type-species is invalid. This mistake remained uncorrected until attention was drawn to it by myself in 1929 (Ann. Mag. nat. Hist. (10) 3 : 229) when I pointed out that the only nominal species included by Hübner in the genus Hemiargus in the Zuträge were the then new nominal species Hemiargus antibubastus and the nominal species Papilio bubastus Stoll, . Holding the then-current view that the taxon represented by the nominal species Hemiargus antibubastus Hübner was the same as that represented by Papilio hanno Stoll, I fell into the error of supposing that on the basis of this subjective identification it would be permissible to accept as valid the selection of the last-mentioned species as the type-species of Hemiargus made by Scudder in 1875. When I returned to this subject in 1934 (: 104), I realized that the procedure which I had followed in 1929 was incorrect and, while maintaining the foregoing synonymy indicated above, I expressly stated that the type-species of this genus was Hemiargus antibubastus Hübner, thus providing the genus Hemiargus Hübner at last with a valid type-species.
About ten years later Nabokov published a revision of this group of species (1945, Psyche 52 : 20), in which he showed that the taxa presented by Hemiargus antibubastus and Papilio hanno respectively were not conspecific with one another and therefore that, contrary to long-established belief, the specific name antibubastus Hübner could not be regarded on taxonomic grounds as a junior subjective synonym of hanno Stoll. At the same time Nabokov brought forward grounds to show that there was a second taxon of specific rank currently confused with Papilio hanno Stoll. This second species had been given the name Hesperia ceraunus by Fabricius in 1793 (Ent. syst. 3 (1) : 303) (the name ceraunus Fabricius having subsequently been treated incorrectly as a junior subjective synonym of hanno Stoll). Finally, Nabokov identified the taxon represented by Hemiargus antibubastus Hübner as being the Florida sub-species of the taxon represented by the nominal species Hesperia ceraunus. Nabokov's arrangement of these taxa is here adopted.
Oppler & Warren, 2003. Butterflies of North America 2. Scientific Names List of Butterfly Species of North America, north of Mexico. Contributions of the C.P. Gillette Museum of Arthropod Diversity Colorado State University include Hemiargus in the tribe Polyommatini.
The higher classification used here follows Lamas (2008).
Learn more about Lycaenidae in Wikipedia.
See images at Butterflies of America.
Search the Biodiversity Heritage Library (BHL) for references to HEMIARGUS and included species.