Polyhymno acaciella vs. Polyhymno new species 2
Hi everyone,
My first, in depth, technical journal post! Go easy on me! ;-)
After assuming that some of our local Polyhmno were P. acaciella, several of us in the Austin area came to the conclusion that what we were calling P. acaciella were likely Polyhymno new species 2 (https://mothphotographersgroup.msstate.edu/species.php?phylo=590594.02). A further note that I found: "Polyhymno n. sp. 2 is a represented at BOLD by BINs AAU7762 and ACR1616 and may represent two cryptic species, possibly undescribed." There does seem to be some variation to what we are calling Polyhymno (both in appearance and range), and this variation might be explained if two cryptic species were involved.
Anyway, all of this prompted me to take a closer look at the state of Polyhymno in Texas. Roughly, what I found is that there seems to be a lot of of misidentification around P. acaciella. Approximately north of I-10, there seems to be a tendency to classify Polyhymno new species 2 as P. acaciella. There are some phenotypic similarities and the iNat AI algorithm will offer up P. acaciella as an option. Polyhymno new species 2 is not currently an ID choice in iNat. However, going through the photos, I don't think I found what I would consider to be an obviously legitimate P. acaciella north of I-10. This jives with the MPG map for the species, though of course those maps can be out-of-date and not always fully accurate. South of I-10, it is a different story. As I went through the photos, it became obvious that in many cases P. acaciella was erroneously being identified as P. luteostrigella, and is likely more common in South Texas than observations would initially suggest (I did not have time to go through all the Polyhymno observations in detail). In general, Polyhymno diversity seems to be highest in South Texas, which generally complicates matters for that region (lots of look alike, potentially undescribed, and potentially cryptic species).
I have mapped out the counties of occurrence of both P. acaciella and P. new species 2 based on my analysis of the iNat observations.
P. acaciella seems to be a South Texas Brush Country species (occurring as far north as I-10, approximately, and as far west as Val Verde County) with most reports in the Lower Rio Grande Valley and along the lower Texas coast up to roughly Corpus Christi. I would assume the species occurs south of the Texas border, but there are no observations from Mexico (likely due to lack of sampling).
The distribution of Polyhymno new species 2 stretches from the south Texas border up to Tarrant and Dallas counties, with most observations coming from central Texas, though there are also a good number of observations from the Dallas area. There are a scattered number of reports east of Dallas and even a few from Louisiana. And Southeast Arizona also has a few observations of Polyhymno that would fit into the Polyhymno new species 2 bucket. Again, it is possible that P. new species two might be composed of several cryptic species. I would also assume this species occurs south of the Texas (and Arizona) border, but there are no observations from Mexico (likely due to lack of sampling). To date, there are also no observations of this species from either Oklahoma or Arkansas.
Since there is often confusion about Polyhymno IDs, I thought I would make a brief remark on field marks (perhaps to be elaborated on later). There does seem to be some noticeable phenotypic differences between P. acaciella, P. luteostrigella, and P. new species 2, at least to my eyes. Namely, the solidly colored (not streaked) thorax/nape is a big tip off that you are looking at P. new species 2. Don't get too focused on the side pattern (the bold white stripe) which can be superficially similar looking between P. acaciella and P. new species 2. The differences between P. acaciella and P. luteostrigella can be trickier, but there is a difference in the streaking pattern and perhaps the coloration (P. acaciella has much darker streaking, whereas P. luteostrigella, the Yellow-striped Polyhymno, has lighter and more gold/yellowish streaking).
@jcochran706 @gcwarbler Not sure how best to share this more widely among our local moth community.
