Saturday, January 5, 2013

Fritillary Frenzy

Update 1/6/2013: I corrected a few places in this article referring to basal, discal, submarginal, and postmedian, and I have added a new page to my blog that builds on a post from last June, click on "Wing Terminology" in the contents bar on the left, or go here.
If you have spent any time trying to identify that large black-speckled orange butterfly in your net or on a flower, you may have joined the club of frustrated fritillary observers.  I used to be in that category, and still revert to it frequently, usually when I haven't compared the different species recently to refresh my memory.  Because of this, I'm surprised I haven't thought to write a blog post about identifying fritillaries (or "frits" as many butterfliers call them for short), but thanks to a commenter on my last post who suggested this, here is an illustrated guide to identifying the seven species of "greater" frits that I am familiar with.
This is going to be a longer article than normal, and you may want to print and keep it for a quick reference.  All photos are my own, so please do not reprint or distribute them for other purposes besides your personal use without asking (comments on my blog are sent to me for approval and won't show up until I post them, so that is the best way to contact me if you have questions).
Background
Fritillaries can be divided into two groups: greater and lesser. As the names suggest, greater fritillaries are larger, usually with a wingspan between 1.5 and 3 inches, compared to the 1 to 1.5 inch wingspan of lesser fritillaries.  Greater fritillaries belong to the genus Argynnis, and lesser frits belong to the genus Boloria.  The genus name of greater frits was recently known as Speyeria and most sources still use that name, although new (post-2010) publications are starting to use the genus Argynnis, as it is the officially-recognized genus now.  While it may be confusing to many people, it is necessary to follow the rules of taxonomy, and Argynnis is the original, historic genus name (see my explanation of the naming process here, and refer to the ICZN website).
Both greater and lesser fritillaries have orange wings with black markings on the dorsal (upper) side.  The ventral side of North American Argynnis is usually marked with silvered or unsilvered spots, and the ventral of Boloria species is usually marked with bands and spots in shades of purple, rust, orange, and white.  Lesser fritillaries are easier to tell apart than greater fritillaries, and will not be described in this article.  There are ten species of greater fritillaries in the Pacific Northwest:
Great Spangled Fritillary Argynnis cybele
Coronis Fritillary A. coronis
Zerene Fritillary A. zerene
Callippe Fritillary A. callippe
Great Basin Fritillary A. egleis
Northwestern Fritillary A. hesperis (unsilvered and silvered forms)
Atlantis Fritillary A. atlantis
Aphrodite Fritillary A. aphrodite
Hydaspe Fritillary A. hydaspe
Mormon Fritillary A. mormonia
I have not had the opportunity to collect or photograph the Great Basin, Atlantis, and Aphrodite fritillaries (A. egleis, atlantis, aphrodite), so these three species will be briefly discussed as a group.  Refer to the Butterflies of America website for an excellent database of photos to help (or further confuse!) you.  The "thumbnail" pages there are organized by subspecies/segregate, and you can click on the photos to see larger versions, or click on the subspecies name to see the full page.  I have hyperlinked the names in the list above to the thumbnail pages for each species for your convenience.
All of these ten species feed on violets as larvae, thus the adults are frequently associated with meadows and prairies where their hosts can be found.  Adults of some species have been known to migrate between higher and lower elevations throughout the Spring and Summer, following the seasonal blooming of flowers (adult nectar source) and growth of violets (larval host).
Another species that is an occasional stray to parts of the Northwest is the Variegated Fritillary (Euptoieta claudia).  It is not in the same genus as the other frits discussed here, and is a somewhat tropical species that sometimes strays into Montana and parts of British Columbia and Idaho, but has not been recorded in Washington or Oregon.  Although it resembles our greater fritillaries and may be mistaken for one of them while in flight, the black dorsal pattern is quite different, and the ventral lacks the silver/cream spots of the Argynnis species listed here.
Pronunciation
Most of these are my educated guesses, some are what I found online.
Speyeria   spay-air'-ree-ah
Argynnis   ahr-gyn'-ness  (probably a hard g, but not sure)
cybele       sih'-bell-ley
zerene       zer-ree'-ney
callippe     kuh-lip'-pey
egleis        egg-lay'-iss (not certain about this pronunciation)
hesperis    hess'-per-iss
aphrodite  aph-ro-dye'-tey
hydaspe    hi-dass'-pey
Great Spangled Fritillary Argynnis cybele
Overall impression: large butterfly, reduced VHW silver spots
Largest of the ten species listed here, with a wingspan of 2 to 3 inches.  The females are much lighter than the males, and look like Mourning Cloaks (Nymphalis antiopa) when in flight.  On both males and females, the silver spots on the VHW are smaller than those of the other Argynnis species.  The VHW is distinctly separated into two ground colors: reddish-chocolate in the discal area and light beige in the postmedian band.  This ground color pattern is very similar to the Northwestern, Atlantis, Aphrodite, and Great Basin frits, but these four can be distinguished from the Great Spangled by their overall size, and the appearance of the silver VHW spots.
Male Great Spangled Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Female Great Spangled Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Coronis Fritillary Argynnis coronis
Overall impression: average size, olive/light brown VHW ground color, silver spots appear to be lightly ringed in black
Wingspan averages around 2 inches.  Dorsal black markings appear slightly narrower (less bold) than Zerene and Callippe, especially in the males.  The VHW ground color is yellowish-brown with olive highlights, and the males in particular have a greenish appearance similar to Callippe.  Female Coronis are easily confused with female Zerene and Callippe fritillaries.  Both males and females are distinguishable by their yellowish or light-olive VHW ground color from Zerene, which has tinges of rust.  Coronis are distinguisable from Callippe by their less-elongated silver spots ringed with a hint of black.
Male Coronis Fritillary, upper Reecer Creek/FR 3507, Kittitas Co. WA
Female Coronis Fritillary, upper Reecer Creek/FR 3507, Kittitas Co. WA
Zerene Fritillary Argynnis zerene
Overall impression: average size, average orange-brown VHW ground color, silver spots are medium-sized and mostly rounded
Wingspan averages around 2 inches.  Dorsal color and black markings are darker than Coronis.  The VHW ground color is tawny brown with rust-colored highlights.  Silver spots are rounded, not as elongated as the Callippe.  Some sources describe the marginal row of silver spots on both the VFW and VHW as being blunt or oval in Coronis and Zerene, and pointed or triangular in Callippe, but as you see in the photos here, these spots are sometimes triangular in Zerene and Coronis, so this is not a reliable indicator.
Male Zerene Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Male Zerene Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Female Zerene Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Callippe Fritillary Argynnis callippe
Overall impression: bold black, washed-out orange, elongated VHW silver spots
Wingspan averages around 2 inches.  Dorsal black markings are bold, orange often appears washed-out, with ventral silver spots seeming to shine through to the dorsal surface, similar to but more obvious than in female Zerene fritillaries.  The VHW has a greenish cast over the yellowish-orange ground color, similar to the Coronis, but the large size and elongated shape of the silver spots distinguish Callippe from that species.
If you use R. M. Pyle's Butterflies of Cascadia for reference, make a note on page 270 that the photo is actually a Coronis Fritillary, not a Callippe as indicated. I'm sure the author won't mind me mentioning that, as he was the one who pointed it out to me.  You'll note in that photo that although the spots appear to be rather large and elongated, they do not nearly cover the VHW surface as you see in the specimens shown here.
Male Callippe Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Female Callippe Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Northwestern Fritillary Argynnis hesperis
Overall impression: pointed/sharp VHW spots
Wingspan averages just less than 2 inches.  The VHW spots can be silvered or unsilvered and cream-colored, and the median row of spots (outer row of the discal area) is almost always quite pointed (see the male in the photos below).  The VHW is also distinctly divided into two ground colors: the disc is reddish-brown and the postmedian band is light beige.
Northwestern Fritillary Female (top, SWA, Okanogan Co. WA), Male (bottom, upper Reecer Creek, Kittitas Co. WA)
Aphrodite, Atlantis, and Great Basin fritillaries (A. aphrodite, A. atlantis, A. egleis)
As mentioned before, I am not familiar with these three species, so this description is only what I have observed from the photos on the Butterflies of America website and my field guides.
Aphrodite may be slightly larger than the other three species. Also, according to Butterflies of British Columbia (Guppy & Shepard), the second brown spot (from the body) in the postmedian band has a faint brown halo around it. You can see it in most of the photos on the BoA website, particular this one here.  Aphrodite also seems to have silvered spots, compared to the usually unsilvered Northwestern Fritillary.  To me, it looks a bit like a cross between Great Spangled and Northwestern fritillaries.
Atlantis used to be combined with Northwestern as one species.  The VHW is generally darker, more of a dark chocolate color than rust.  It is also a more northern species, having never been recorded in Washington (historic records are now all described as A. hesperis in WA), ranging through British Columbia, Alberta, and northern Idaho and Montana.
Great Basin appears to me more like Zerene in color and pattern, but has slightly shorter wings, sort of stubby-looking.  It is a more southern species, ranging from California and Nevada up through eastern Oregon and parts of eastern Washington, into Idaho and Montana.
Hydaspe Fritillary Argynnis hydaspe
Overall impression: dark and red
Wingspan averages just less than 2 inches.  The VHW spots are usually unsilvered and cream-colored, although the marginal row is occasionally lightly silvered (2nd and 3rd specimens in the photos below), and the spots in the discal area tend to be almost square compared to the Northwestern Fritillary.  Hydaspe can be easily initially identified from a distance simply by seeing the deep reddish-orange color of the dorsal side, but verification of the species comes from the VHW color, which is the deepest rust color out of all the other species described here.  Individuals that are faded may sometimes be confused with the Northwestern Fritillary and the others in that group, but the postmedian band of Hydaspe still has a reddish color, compared with the yellowish postmedian band of the Northwestern Fritillary.
Male Hydaspe Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Female Hydaspe Fritillary, Sinlahekin Wildlife Area, Okanogan Co. WA
Mormon Fritillary Argynnis mormonia
Overall impression: small, finely marked, ventral is bright yellow-orange
Smallest of the "greater" fritillaries with a wingspan averaging 1.5 inches.  The black dorsal spots are cleanly marked.  There are two general forms of Mormon frits, one has bright, silvered spots and a VHW base color of light tawny orange, while the other form has a greenish sheen over the VHW, and the spots are lightly-silvered or unsilvered.
Male Mormon Fritillary, various locations in WA
Female Mormon Fritillary, Haney Meadow and vicinity, Kittitas Co. WA
Ready for a test?
Here is a set of photos to test your abilities.  None of them are included in the photos above, so you can't match them up that way.  There is at least one photo for each of the seven species I described (no Aphrodite, Atlantis, or Great Basin), but I included a few extra photos to make it harder, including two females that resemble other species.  Two specimens in particular are quite tricky, and I'm not even sure I have them identified correctly, so they will be marked with an asterisk* in the answers.  Write down your best guesses, and then check the answers at the end of this article (below the conclusion paragraph).  Explanations of their identification will be in a separate blog post next week.
Conclusion
I hope that this guide has helped you to understand the differences between these species, and given you the confidence to try your hand at identifying the next frit you see.  Keep in mind that while you may be able to see the differences between these specimens, when you are holding a fritillary in your hand and trying to identify it, you may find yourself confused all over again.  I have to refresh my memory every Spring in order to maintain any semblance of proficiency at correctly identifying these critters!  After some practice, it will become second-nature for you to take a quick glance and simply "know" that an individual is a particular species, without having to carefully examine the markings and define how you came to that conclusion.  Also keep in mind that these butterflies are variable, some species more so than others, therefore it is helpful to study series of photos such as what I have provided, and what the Butterflies of America website makes available. That way, you can compare the variations and decide which best matches the one you have.
Happy chasing!

All photos and text copyright Caitlin C. LaBar

Photo-test Answers: A - Hydaspe male; B - Zerene male; C - Great Spangled male; D - Northwestern male; E - Zerene* male; F - Hydaspe male; G - Coronis* female; H - Callippe male; I - Mormon male; J - Zerene male; K - Coronis female; L - Coronis male

6 comments:

  1. WOW! Great job, wonderful post. I didn't do well on the quiz.

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    1. Thank you! and don't feel bad, like I said, I purposefully picked some tricky ones for the test, and you can't tell what size they are from the photos, so that makes it a little harder too.

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  2. Great work- Thank you! Do you think your 'key' works for all of Washington? The problematic sp. are really only the callippe complex (callippe-hesperis-egleis-zerene-coronis-hydaspe); all the others are fairly easy to ID in the field I think.
    Do you have any comments about argynnid subspecies in your area?

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    1. I think my descriptions apply to most of Washington and Oregon. It is the eastern and southern edges where things start to become more fuzzy, especially when A. egleis and A. atlantis enter the mix. At the very least, this key should help narrow it down (i.e. zerene/egleis, hesperis/hydaspe, etc). I'm not as familiar with the subspecies, that's better left to J. Pelham and others to sort out.

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  3. In looking at my series from various states/provinces I am also struck by:
    1. Callippe is very different from the other sp. in dorsal backround coloration in most areas- the least 'red' of all the frits and a buff tan in most places. The ventral HW silver spot elongation 'key' hold true though- especially in ID and NV. Even in CA and AB the ratio of length to width of the spots is about 2:1.
    2. The smallest atlantis is larger than the largest of the 6 sp. callippe complex except for some hesperis outliers, and the largest mormonia is smaller than the smallest callippe complex frit.
    3. For the zerene and hydaspe series I have from AB, WY, CO, ID, etc. your 'rule' about post median band coloration holds true.
    Based on your rules and some rules from some of the guides it might be possible to key out the whole 6 species western US callippe complex with 90% certainty (??). LP Grey said this was not possible but I am feeling more optimistic. What do you think?

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  4. I think I was sleepy when I wrote that post last night. I meant to say "the smallest aphrodite", NOT 'atlantis.' And looking at more series this am this is true for eastern US aphrodite, but not western US- so scratch that idea. But since aphrodite doesn't occur in the NW and is pretty rare west of the Rockies, maybe we can forget about it. Obviously, cybele is a larger bug than the complex species- but we already knew that.
    Still, for the callippe complex, if we can tell callippe from coronis by the silver spot shape and zerene from hydaspe by the VHW PM band coloration we are doing pretty well.

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