Exelis pyrolaria and Exelis ophiurus in Texas

It is a fact that Exelis pyrolaria and Exelis ophiurus are difficult to separate based on general appearance. I really didn't think they were, based on the few pics at MPG and on moths I've seen and identified (or thought I did) in the past. But the more I looked into the identification of the Texas SWGs (slender-wing geometrids), the more I realized that these two Exelis species often cannot be separated with certainty on the basis of general appearance. I went to BOLD public data pages where there are 5 E. ophiurus and 7 E. pyrolaria on the public records data pages. As is unfortunately the case on BOLD, the genetics may say one thing, but most of the specimens are scaleless, patternless, and completely uninformative.

There are 25 pyrolaria specimens on the BOLD taxonomy page, but BOLD identifies them as 7 pyrolaria (same as on the public data page), 1 Exelis dicolus, and 17 unidentified. I cannot figure out how to look at the locality data for any of these specimens except the 7 on the public data page for the species. Of those seven, four 4 from Bartlesville OK (the NE corner of that state) two are from KY and one from GA. At the BOLD taxonomy page, the distribution of E. pyrolaria is described as east of the Mississippi River and south of southern Illinois. The map shows a dot east of the Mississippi River and one in OK.

There are 9 E. ophiurus specimens at the BOLD taxonomy pages. Visually they are not particularly useful. BOLD identified these as 5 E. ophiurus and 4 unidentified. Again, I cannot figure out how to see the locality data for those four specimens. Of the five identified, one is from Florida, and while BOLD does identify it as ophiurus, it places it in a separate bin with some Atlantic seaboard Tornos scolopacinaria. Of the remaining four identified specimens, one is from OK about 100 miles north of Dallas, and the other three are from Texas, (Irving, Pedernales Falls, and Sanderson.)

I cannot explain the three locality dots on the MPG in the Edwards County area for E. pyrolaria. I think there is a good chance that those are based on visual identifications, but it’s possible one of the dots is a specimen that Ann H sent to BOLD.

The original literature, (Rindge 1952) did provide some useful information. In this paper, Rindge (1952) describes dicolus and ophiurus as new species. Rindge saw only pinned specimens. Early in the paper he recommends that genitalia be the basis for identifying the species. Rindge looked at 90 specimens of Exelis (3 holotypes and 87 others). He looked at 37 ophiurus specimens, 6 dicolus, and (I assume) 47 pyrolaria.

Rindge described pyrolaria (Guenee, 1857) as a dark moth species--dark gray or dark grey-brown. Of all the Exelis, Rindge states that pyrolaria can be “recognized by the dark gray color of the wings, although in old or worn specimens this fades to a grayish brown.” I mention that the gray live specimen of pyrolaria in the image by Mark Dreiling and pictured on the MPG page for pyrolaria is one that is barcoded and identified as pyrolaria at BOLD.

Rindge described ophiurus (this is the original description) as more pale (than pyrolaria) and ochreaous in color (reddish-brown). Neither of these characters may apply to the live specimens we deal with. I haven't seen a live specimen I'd identify as "ochreaous" in color. However, of the 7 pinned specimens at BOLD, considering the scaleless condition of several, all are dark specimens. One of the 5 ophiurus BOLD specimens (a beat-up old crappy TX specimen from Irving) could be considered dark.

The type locality for ophiurus is Texas: Burnet County: Burnet. Rindge states in the description of ophiurus that is it paler than pyrolaria, and the lines on the wings are much more distinct--however, the discal spot that both typically have is "weaker" in ophiurus than in pyrolaria.

Perhaps most helpful. Rindge found pyrolaria only east of the Mississippi River. This statement is repeated by BOLD, although their records include the four from northeast OK. All of Rindge’s specimens of ophiurus were from Texas and there are paratypes from Bexar, Val Verde, Edwards, McKinney, and Terrell counties. All six dicolus seen by Rindge were from Arkansas.

So basically, in the absence of dissection of the genitalia or barcode to indicate otherwise, I consider it most likely that the Exelis found SW Hill Country/ Edwards Plateau/Trans-Pecos are Exelis ophiurus. I see no evidence that pyrolaria ranges anywhere near that far into Texas. I'm not aware of definitive evidence to indicate that pyrolaria is in Texas even to Austin.

Posted by ptexis ptexis, February 28, 2018 19:20

Comments

Therefore, most likely all those that we have been calling Exelis pyrolaria are actually E. ophiurus.

Posted by dianaterryhibbitts over 4 years ago (Flag)

Regarding "ochraceous", most definitions call it "light brownish yellow"; I think of it as sort of orangish yellow. I can't find any refs that indicate ochraceous to be "reddish-brown" as you suggest. Q: In other terminology, what is the color of the material called "ochre"? A Google Images search for just the word "ochre" is information, if not definitive!

Posted by gcwarbler about 4 years ago (Flag)

The English Oxford dictionary defines "ocher" as the US version of the English term "ocre" and defines it as "an earthy pigment containing ferric oxide, typically with clay, varying from light yellow to brown or red." The most common definition of "ochraceous" is that it refers to the color of ocre.

Several definitions of the color of ochre (ocher) define it as a light yellowish brown or or orangish medium tan. But ocre (ocher) can be darker and more reddish. The precise color seems to vary because of variation in the mineral on which the pigment is based. Consequently there is considerable variation in what is "ochraceous". For that reason, it is unsatisfactory to use the single term "ochraceous" in a modern description.

Looking to the classic work of Ridgway (1912) "Color Standards and Color Nomenclature", there is an extraordinary variation identified and illustrated as "ochraceous." Ridgway recognizes the follow variations: ochraceous buff; light ochraceous buff; ochraceous orange; pale ochraceous orange: ochraceous tan; pale ochraceous tan; ochraceous salmon; pale ochraceous salmon; ochraceous tawny (which is reddish-brown to my eye); ocher red; flesh-ocher; and olive-ocher. There is no mention of the color "ocre" or "ochraceous" on their own.

I interjected into my post that ochre was reddish brown. That is how i think of ochre and I think that is because a set of paints I owned as a child (long time ago) included a jar of ochre that I remember as reddish-tinted medium-brown. I think that you are correct, Chuck, that "ochre" on its own does more commonly refer to a pale yellowish brown.

Posted by ptexis about 4 years ago (Flag)

After seeing quite a few Exelis moths at a recent bioblitz in Mills County, TX, I once again looked over the very confusing information on MPG, BG, and BOLD on this genus, and made my usual periodic pilgrimage to the original literature. I think the MPG and BOLD information is a total mess. There are several problems here, most of which you highlight in your great analysis above. Most importantly, the origin of identifications of moths submitted to BOLD for barcoding is unexplained and unknowable. I am really losing faith in the relationship of barcoding results and identifications; it's such a black box and I have uncovered so many erroneous assocations in other genera I've studied. IMHO, there needs to be more transparency and explicit acknowledgement of the source of IDs associated with every specimen and with each barcode BIN. But I digress...
The barcode results themselves are quite confusing except that E. ophiurus--whatever it looks like--separates quite a bit (3%+) from other barcoded Exelis. But the sampling of all three "species" is so patchy and geographically biased that it's hard to generalize about relationships or geographic ranges from barcode results.
So going back to Rindge's 1952 monograph on the genus is important. But even that source has some issues. His use of the term "ochreous" for the ground color of E. ophiurus is just inexplicable. I am hard-pressed to find any example of Exelis which remotely fits into an "ochre-like" or yellow-orange color. Ambient lighting does affect the color which I see in the array of hundreds of photos of Exelis on iNat including nearly 100 from Texas. But I would term the ground color of Texas moths as pale gray to slightly brownish gray or buff-gray. Often the gray ground color looks rather silvery and the brownish tint is obscure. However, @ptexis's images tend to show a richer buff-gray ground color, and I suspect this again is a result of flash settings and ambient light differences.
Here's my "quack-like-a-duck" rule of thumb, primarily based on Rindge's original work:
-- All Texas Exelis should be summarily presumed to be E. ophiurus until/unless they are dissected and found to be different.
-- All Exelis east of the Mississippi River may be safely assumed to be Exelis pyrolaria unless/until ...
-- Exelis found in Oklahoma, Arkansas, and Missouri should be placed at genus level until/unless dissecting and barcoding are found to be reliable to separate the three current species.

Posted by gcwarbler 4 months ago (Flag)

Thank you for the discussion and the research. I think my thoughts on BOLD run parallel to yours. I agree with your proposal on dealing with Exelis.

Posted by ptexis 4 months ago (Flag)

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