Some recent sightings* of Acronicta moths have prompted me to try to dig into the original descriptions of certain species to look for distinctions. The three species are:

9222 - Acronicta paupercula Grote 1874

https://bugguide.net/node/view/557337

9223 - Acronicta lepetita Smith 1908

https://bugguide.net/node/view/391023

9225 - Acronicta vinnula (Grote 1864)

https://bugguide.net/node/view/45332

• Some of the recent observations which need attention include (but are not limited to):
  https://www.inaturalist.org/observations/12850205
  https://www.inaturalist.org/observations/12735869
  https://www.inaturalist.org/observations/12412055
  https://www.inaturalist.org/observations/12000551
  https://www.inaturalist.org/observations/11851544

The original description of paupercula by Grote in 1874 is of little help because it only compares that species to A. exilis, a very different looking species of the E. US.
https://www.biodiversitylibrary.org/item/17720#page/225/mode/1up
I can't find Smith's original (1908) description of lepetita. The only description of these three similar species that I can find online is in Seitz' 1919 massive work: Macrolepidoptera of the World, Part 2 American Macrolepidoptera, Div. 7 Owlet Moths, p. 21. It's in German and my German is all but non-existent. The volume can be viewed online starting with the following title page, or downloaded from the Biodiversity Heritage Library from this page:
https://www.biodiversitylibrary.org/item/39808#page/7/mode/1up

Below I'm pasting in the text from page 21 regarding the three species and hoping someone with German proficiency can help translate it. (Seitz illustrates the three species on his plate 3 but the hand-paintings are pretty simplified and the titles and legend are illegible on the online version from the Smithsonian, so they are of no help.) So below is the text from Seitz, 1919, p. 21. This was OCR-ed and I've tried to read through it for typos, but there may still be some spelling errors. The term "Hflgl" is apparently an abbreviation, but I can't find the full word:

A. vinnula Grt. (3 c). Eine kleine weißliche, etwas olive getönte Art, die mit keiner anderen zu verwechseln ist. Der schwarze Verbindungsstrich zwischen den Querlinien fehlt, letztere mehr oder weniger olivgrün; der schwarze Wurzelstrich entsendet in der Mitte einen Haken zum Ird. Hflgl weißlich, braun bestäubt. Canada, Vereinigte Staaten bis Texas. Die grüne Raupe trägt auf jeder Warze ein steifes Haar, das von kürzeren kreuzförmig umstellt ist. Sie lebt an Ulme.

A. paupercula Ort. (3 c) ist der vorigen etwas ähnlich, hat aber mehr bräunliche oder besser schmutzig rötlichgelbe Bestäubung auf dem granweißen Grund, die Zeichnung ist sonst ähnlich, die vordere Querlinie und besonders der Mittelschatten sind aber viel undeutlicher. Texas.

A. lepetita Sm. (3d) ist ebenfalls der vinnula ähnlich, kleiner, die Grundfarbe ist blaugrau, olivenbraun gemischt besonders vor dem Saum, Wellenlinie ganz undeutlich. Hflgl dunkler. Aus Texas beschrieben.

If you can translate German, please add a comment here or send me a personal message. Or if you know of someone who might help with this please direct them to this journal post.

Danke!

During an iNat bioblitz in the Del Rio/Amistad area of Texas in early April 2018, we had the opportunity to document “Bandana Daisy” (Gaillardia coahuilensis), a very locally occurring relative of the common and widespread Indian Blankets (Gaillardia pulchella). Bandana Daisy was first described by Dr. Billy Turner in 1977* from specimens in that area, along with material from adjacent Mexico.

Typical examples of these two species can be seen here:
Bandana Daisy: https://www.inaturalist.org/observations/12577376
Indian Blankets: https://www.inaturalist.org/observations/12936811

Bandana Daisy is superficially quite similar to Indian Blanket, but can be readily separated by looking for the following characters:

Ray flowers: Although quite variable, the ray flowers of Bandana Daisy are usually divided deeper than those of Indian Blankets. Typically they are cut about 40-50% of the way to the base while those of Indian Blanket are rarely incised more than about 30%. Also, there is a tendency for the ray flowers of Bandana Daisy to have more yellow on them, occupying as much as 50% of the ray flower. Some populations can have completely yellow rays. This character is also variable in Indian Blanket but typically they are 60 to 90% red.

Disk flowers: This can be one of the easiest characters to observe. The disk flowers of Bandana Daisy have very short fuzzy hairs, while those of Indian Blanket are clothed with long tangled hairs which makes each little disk flower look like a starfish or medusa-head. The overall effect is of a relatively smooth disk for Bandana versus a frizzy disk for Indian Blanket.

Phyllaries: On Bandana Daisy, these are covered with very short curled hairs; there are no long marginal hairs. On Indian Blankets, the phyllaries are copiously covered with long spreading hairs including on the tops, margins, and base. Some of those hairs are nearly as long as the width of the phyllary. Sometimes the tips of the phyllaries--which show through in a top view of the flower--lack the long hairs, so be sure to look at the flower from a side view or the underside to examine all of the phyllaries.

Good close-up images with top and lateral views of the flowers of each species will easily show these distinct characters.

Range: http://bonap.net/MapGallery/County/Gaillardia%20coahuilensis.png
Bandana Daisy basically replaces Indian Blankets in the counties around the "hump" of the Rio Grande, centered on Val Verde and Terrell counties. It is mapped well up into Crockett County, along with Kinney County to the east. There are a few records in the s.w. corner of Edwards County, in western Uvalde County, and in northern Maverick County (Turner et al. 2003). It co-occurs with Perfumeballs (Gaillardia suavis) over this entire range.

Turner, B. L. 1977. A New Species of Gaillardia (Asteraceae-Heliantheae) from Northcentral Mexico and Adjacent Texas. Southwestern Naturalist 21(4):539-541. (Available for download from JSTOR.)

Turner, B. L., H. Nichols, G. Denny, O. Doron. 2003. Atlas of the Vascular Plants of Texas. Sida 24. Botanical Res. Inst. Texas.