ID of Crescent species (Phyciodes)

Projects The 2nd Vermont Butterfly Atlas (2023-2027)
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I am seeing a lot of Crescent sp. (Phyciodes) identified to species. Beware that this is really really hard and the science is still working out the species in fact. But, this blog post is spot on and a must read - A Tale of Two (or More) Crescents | LepLog. It is from Maryland, but applies to here in Vermont.

Here is a key passage from that post:

Distinguishing these three species is a considerable challenge. The females are indistinguishable because females of all three species are identical in morphology and their antenna clubs all vary from black to orange. In specimen series, tharos females are smallest, the bivoltine cocyta females are slightly larger, and univoltine cocyta females are the largest. Photos won’t do any good and are only identifiable to genus (Phyciodes), though one can get them in the ballpark by flight date. Females are best identified by association with males within population concentrations.

The males, on the other hand, can be distinguished only by a single character: the lower (ventral) side of the antenna club. P. tharos males have black antenna clubs with some gray on the lower side. Some P. tharos males have a slight orange tip on the upperside of the club, but the underside of the club is not orange. P. tharos often lives in concentrations around aster hostplants and fly in April, July and September, though their flights can vary somewhat from year to year.

When in doubt, please just ID as the genus: Crescent sp. (Phyciodes)

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This is a detailed note sent to me by Harry Pavulaan, who has examined a lot of VT specimens from the first atlas.

Yes, the Phyciodes continue to bother those of us dealing with taxonomy, systematics, and evolutionary relationships. You are probably aware of the recent results of genomic research generated by the team of Nick Grishin and others. In summary, the following taxa are now recognized as full species in the eastern U.S.:

Phyciodes tharos
Phyciodes cocyta
Phyciodes diminutor

Phyciodes incognitus
Phyciodes orantain

In Vermont, you have the first three. In summary:

P. tharos is the taxon with the solid black antenna clubs on the males. The key here is in the males. The underside of the clubs is generally black but most specimens have some gray. What confuses most people is the fact that many tharos males have an orange TIP on the upperside of the clubs. This is just a variant. The underside, in this case, is still black and some individuals with gray thrown in. Male tharos males do not have orange on the underside of the clubs. Tharos has three broods down here in Virginia. I don’t know the brood sequence in Vermont, but it has at least two broods and very possibly a partial third.

P. cocyta is the big taxon. Univoltine. According to James Scott, it occupies the higher elevations. The key here is, again, in the males. Males have orange on the underside of the antenna clubs. They usually have that orange tip on the upperside of the clubs like tharos. But the key in identifying cocyta is by the orange on the underside of the clubs.

P. diminutor is the smaller, bivoltine version of cocyta. Males are virtually identical to cocyta but are considerably smaller, thus the name. It inhabits low elevations, valleys and the Lake Champlain area. They also have the orange (underside) antenna clubs.

The common belief is that the cocyta/diminutor complex males have considerably more orange on the dorsal hindwing, with reduced postmedian markings, whereas tharos has a well-developed band of markings. This is definitely unreliable. While cocyta and diminutor do have the extensive orange hindwings, this can also be found in tharos – quite commonly! I have reared entire “families” of tharos here that look as much like cocyta, with very orange wings. The antenna clubs are then the primary differentiating character.

The females are much more difficult to distinguish. Tharos and cocyta females are identical except for size. Diminutor females, on the other hand, have very dark uppersides. Often so heavily darkened that they remind one of the southern P. phaon females. The antenna clubs of the females in all three species are highly variable. Most have variably black/orange antenna clubs but some females have either solid black or solid orange clubs. This confuses people. The best way to distinguish females is by association with the males they are flying with. Identify the males, then you know what the females are.

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Here is a report James Scott did on the data and specimens from the First Vermont Butterfly Atlas: https://mountainscholar.org/bitstream/handle/10217/86009/Papilio_New_Series_23_rev.pdf

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Holy cow !! The underside of the club ??!! Makes me wonder about all my previous id’s !!