2023年08月28日

Metarranthis Pictorial Key

This is a work in progress, feedback welcome.

1a. Forewing PM line with sharp angle … 2

1b. Forewing PM line without sharp angle … 5

2a. Terminal area of wings strongly mottled … 3

2b. Terminal area of wings washed out, not strongly mottled … 4

3a. Wings pale, base color light tan … M. indeclinata

3b. Wings darker with some purplish shading … M. refractaria

4a. Wings dark red to purple; smaller than any other Metarranthis … M. homuraria

4b. Wings varying from very pale to dark brown, but never with dark rusty red base color; size typical of Metarranthis … M. hypochraria (including M. mestustata)

5a. AM and PM lines composed of silvery metallic scales; lines often interrupted; dark reddish to purplish base color … 6

5b. Not as above … 7
6a. Moth larger than any other Metarranthis, found along the Atlantic or Gulf coasts as far north as the Carolinas … M. lateritiaria

6b. Moth typical in size of Metarranthis, found along the Atlantic Coast from the Mid-Atlantic northward to New England … M. near lateritiaria

7a. Hindwings with contrastingly bright yellow costas, rest of wings rusty orange … M. obfirmaria

7b. Not as above … 8
8a. Bright yellow median areas contrasting with bright pink basal and terminal areas, range restricted to the Midwest … M. mollicularia

8b. Not as above … 9
9a. PM lines smooth and straight to evenly curved … 10

9b. PM lines sinuous or with distinct bulges … 11

10a. Moth reddish brown, restricted to Atlantic and Gulf coastal habitats … M. pilosaria

10b. Moth dull brown, occurring in both coastal and some inland habitats in the Northeast … M. apiciaria

11a. Dark median and basal areas contrasting with pale median areas … 12

11b. Median area not contrastingly paler than the rest of the wings … 13

12a. Wings heavily reticulated … M. angularia

12b. Wings appearing smooth and not heavily reticulated … M. amyrisaria (in part)

13a. Base color of wings gray without any hint of rusty red coloration, restricted to boreal habitats across Canada and extreme northern USA … M. warneri

13b. Not as above … 14

14a. A small smoothly patterned Metarranthis with an even dusting of darker scales throughout the wings; mainly Northeastern … M. amyrissaria (in part)

14b. A larger more mottled Metarranthis … 15
15a. A tan-colored species that flies in the early spring (mainly April) in the Northeast and Appalachan regions … Metarranthis new species 1

15b. Mostly late-spring to early-summer flying; extremely variable and widely distributed across the continent, not always easily separable from M. amyrissaria where both occur … M. duaria

由使用者 paul_dennehy paul_dennehy2023年08月28日 18:58 所貼文 | 2 評論 | 留下評論

2023年08月07日

Acrolophus of the East- A Rough ID Guide

Acrolophus is a common genus of moths found throughout most of the United States, with the highest diversity in the East and the Southwest. There are several undescribed species, and identification in the West is challenging due to the lack of available references. However, most of the eastern species are named, and identification from photos is usually possible for intact specimens. This guide is meant to allow for identification of Acrolophus east of the Great Plains. Numerous additional species occur from central Texas west through California which are not included here.

I’ve divided the 16 eastern species into groups:
-Group A: large species (forewing length >1 cm) with small palps pointing directly upward in both sexes (1 species: arcanella)
-Group B: large-to-medium-sized species (forewing length ~1 cm or >1 cm) with palps facing forward to form a snout in females and appearing “combed over” the back of the thorax in males (7 species: popeanella, propinqua, plumifrontella, mortipennella, walsinghami, texanella, and mora)
-Group C: small species (forewing length <1 cm) with palps facing forward to form a snout in females and appearing “combed over” the back of the thorax in males (1 species: simulatus)
Group D: small species (forewing length <1 cm) with small palps (7 species: panamae, heppneri, spilotus, forbesi, piger, cressoni, and mycetophagus)

These are NOT “species groups” in the taxonomic sense, just groups that I’ve placed them into for ease of identification.

Group A:

Arcanella: the only species with FW length >1 cm, a robust thorax, and directly upward-pointing palps that flies in the summer. Some A. mora may have palps that appear upward-pointing in some photos, but A. mora is easy to identify from its flight season (September-October vs May-August for arcanella). These images show the robust thorax (much thicker than the head) and distinctive palps well:

Note that from Texas westward, several other species fit this description as well, such as minor, arizonellus, and davisellus.

Group B:

Mora: Most easily recognized by its late flight season (September-October), long after other Acrolophus in its range have peaked. It is mostly a Northeastern/Appalachian species, flying along with other late-season specialties like Papaipema and Metaxaglaea.Palps are shorter than others in this group, the female’s sometimes not even visible in photos. Warm brown overall with obscure yellow-brown patches along the inner margin.

Walsinghami: The smallest in this group, and the most range-restricted. This is the most abundant Acrolophus by a long way in Penninsular Florida, especially in urban and suburban habitats, but it does not occur over the rest of the East. It typically has a “W-mark” on the forewings and a white discal dot, as seen nicely here:

However, the coloration is extremely variable, with the pattern sometimes being all or partly obscured:

In general though, if you’ve found an Acrolophus at a building light in Penninsular Florida, it’s probably this one.

Mortipennella: Common in the Midwest and Southeast, but rare to absent in the Northeast. Males have exceptionally long palps and a very “dainty” thorax (barely thicker than the head), which means the palps appear to be held well above the thorax, not right up against them:

Females have a distinctive “triangular” look from the side, due to the thin thorax, thin head, and tapering palps:

The female’s palps are shorter than those of plumifrontella, but longer than those of any other females in this group.

Plumifrontella: In fresh condition, the pinkish coloration makes this species unmistakable:

Females are further distinguished by their exceptionally long palps:

Which can unfortunately become damaged or broken off, making the ID tougher:

Texanella: Like mortipennella, mostly a species of the Midwest and Southeast, rare to absent in the Northeast. Structurally, palps are similar to walsinghami, popeanella, and propinqua, but the wing pattern when fresh is usually distinctive: a “stripe” runs from the middle of the costa diagonally to the anal angle in both females (left) and males (right):

The wings are darker distal this stripe. The wing itself is actually creased along this stripe as well, so even in worn or poorly marked individuals, the “stripe” can be seen in the form of a wing crease, like in these:

Melanic individuals, like the right one shown above, often have a few white scales along the crease. White scaling occurs on several other Acrolophus when fresh as well.

Popeanella: A pretty variable species, easily recognized in its yellow-striped form:

That becomes a bit less distinctive in forms where the stripe is darkened:

And sometimes loses the yellow altogether, but the placement of the rest of the patches on the wings remains the same:

In these plain forms, this species can sometimes be very difficult to distinguish from dark specimens of propinqua.

Propinqua: Most common in the Southeast, this is the toughest of this group to identify, as individuals tend to have variable indistinct patches on the wings that approach poorly marked specimens of texanella and popeanella. Here are the “standard” female and male patterns, brown, splotchy, a bit smaller than popeanella, similar to popeanella and texanella in palp structure:

But melanic forms of propinqua are common, especially in coastal habitats. They are usually black with varying amounts of gray, like these:

And sometimes they are completely black with white overscaling, like these:

Group C:

Simulatus: This species is very distinctive, has very long palps in both sexes, and appears to be widespread in the Southeast, with iNat records including most states from NJ south to FL west to TX:
Males:

Females:

Group D:

Mycetophagus: Southeastern species, completely unmistakable with huge frills coming off of the forelegs:

Panamae and heppneri also have these frills, but they’re much smaller in those species.

Cressoni: Most abundant in Texas, Oklahoma, and surrounding areas, but also occurs in the Southeast and Arizona. The only small Acrolophus with small palps and raised scales all over the forewings, giving the moth a bumpy appearance:

The only Acrolophus this could be mistaken for in the East is simulatus, but that species has long palps. However, the genus Amydria appears to be frequently confused with A. cressoni on iNaturalist. Amydria has no raised scales on the forewings, which allows it to be separated from cressoni with relative ease:

Panamae: Mostly Southeastern, but occurring as far north as coastal New York State. Small, mostly brown, with some silvery and orange scales (more of the orange becomes visible as the moth fades), with little frills on the legs:

Heppneri: A Gulf Coast species, similar in size to panamae, with the same little frills on the legs, but extremely plainly marked, basically entirely brown except for a dark discal spot:

Spilotus: Apparently a rare species of the Southeast, looks like heppneri but without the foreleg frills and with black speckling overlaying the wings:

Forbesi/piger: Piger is widespread in the Southeast as far west as central Texas, and forbesi is found throughout this same region, but is apparently less common. According to Peter Jump, the species are not separable in photos unless the eyes are seen very close-up- “eyes in A. forbesi are naked or with very short setae and look naked; eyes in A. piger are setose”. So perhaps these shouldn’t be taken to species based on live photos. Here’s what they look like; they’re pretty distinctive among this group:
Males:

Females:

The males have a dark triangle marking on the forewings, and both males and females are more gray than the rest of this group.

And that’s all the Acrolophus one is likely to encounter in eastern North America. Hopefully when a revision comes out, some of the tougher pairs of species will be cleared up a bit.

由使用者 paul_dennehy paul_dennehy2023年08月07日 21:14 所貼文 | 9 評論 | 留下評論

2023年07月16日

The existence of "white form male" Colias eurytheme/philodice

Colias eurytheme and C. philodice are abundant species in Pennsylvania, and females of both species come in both a "yellow" form and a "white" form, in similar proportions. In 2001, on a visit to the Penn State University entomological collection, I was surprised to see a male specimen of Colias eurytheme/philodice from Pennsylvania that had all the yellow/orange on the wings replaced by white, like a white form female. The black scaling was not faded at all, but the yellow was entirely missing. I was amazed by this specimen, and hoped that one day I might find one like it myself.

Fast-forward to 2021- I was sorting the specimens in the Fort Indiantown Gap Lepidoptera collection, and I found two more of these "white form males", both of which were collected in the mid-2010s. The labels indicated that they had both been collected in bee bowls, and neither one was in great condition, but they were apparently the same form I'd seen 20 years earlier in the Penn State collection. One of them had a little bit of orange near the costa of the hindwings, and the other had no yellow/orange at all.

This summer (2023), I started using bee bowls to sample my property for pollinators, and was surprised to find several apparently "white form male" Colias in my bee bowls. But it quickly occurred to me that these were specimens that had been soaked in soapy water and exposed to direct sunlight for several days- likely, it seems, that they simply had been bleached by these conditions. After soaking the specimens in alcohol to clean off the soapy water, softening them, and spreading them, here's what I ended up with:
https://www.inaturalist.org/observations/173267124
Basically identical in color to the specimens I'd seen at Indiantown Gap, and, but for the small patch of orange remaining on the hindwing costa, identical to the one I'd seen at Penn State.

Given that the white specimens from Indiantown Gap were bee bowl specimens, mine are bee bowl specimens, and I've never seen a live photo of this form, I'm now questioning whether this form is a thing at all. I've found other pinned specimen photos online of them, like this one:
https://bugguide.net/node/view/503074
But never a freshly eclosed, non-faded living individual. If anyone has seen such a thing, I'd love to know about it. Otherwise, I'm leaning toward concluding that this is just an odd specimen-fading quirk, and not an actual genetic aberration. I'd love to be wrong though.

由使用者 paul_dennehy paul_dennehy2023年07月16日 19:14 所貼文 | 0 評論 | 留下評論

2020年08月17日

Apantesis vittata and the self-replicatory nature of misidentifications

I've been meaning to post on this subject for a while, and after once again working to correct misidentifications of Apantesis vittata last night, I figure now is as good a time as any.
First off, some background on this species. Apantesis vittata is a moth found in the southeastern USA. It is replaced to the north by the visually extremely similar Apantesis nais. The main differences between these species are the shape of the male genitalia, visible only by dissection under a microscope. The wing patterns are variable in both species, and there is a lot of overlap, especially in the females. In addition, the very abundant Apantesis phalerata occurs throughout the eastern USA, flying with both vittata and nais.
A typical example of a male A. vittata can be seen here: https://bugguide.net/node/view/1492279/bgimage
A typical example of a male A. nais can be seen here: https://bugguide.net/node/view/1755934/bgimage
The trend is for vittata to have reduced forewing markings and spots on the collar of the thorax, which nais lacks. However, this is only a trend, and male nais frequently have these markings, as is the case here: https://bugguide.net/node/view/1755935/bgimage
Here is a typical male of A. phalerata: https://bugguide.net/node/view/10566
Note that the hindwings have a broken black border, are pink at the base, and fade to yellow toward the outer edge. Females have pink hindwings without the yellow portion.
Females of all three of these species have reduced forewing markings and spots on the collar, such as this individual: https://bugguide.net/node/view/633456/bgimage
Based on specimens examined and dissected, A. vittata appears to be restricted to the Gulf Coast and the Atlantic Coast north to the Carolinas. Here is a summary of the species group by @neoarctia, an expert on the Apantesis: https://tinyurl.com/y6ksj78o

Now, here is the major problem with this group. Check the records on iNaturalist, BAMONA, and Moth Photographers Group, and you'll see dozens upon dozens of records of Apantesis vittata from all over the eastern USA, as far north as New England. Could all those records be wrong? How could something like that happen? Well, the answer is, yes, they're all wrong, and how it got to this point is the main reason I'm making this post.
I think it all goes back to BugGuide, one of the earliest sites with user-submitted records of moths. Prior to 2015, there were many photos of Apantesis vittata posted from all over the eastern United States. The difference listed on the page there for A. vittata vs. A. nais was A. vittata's "reduced forewing markings". Of course, females of both species have "reduced forewing markings" compared to the males, and what was actually happening on that page was male nais were being posted as "nais" while female nais were being posted as "vittata". I moved all these female nais off the vittata page in 2015, but unfortunately, the records had already made their way to Moth Photographers Group, where the dots remain to this day, suggesting that vittata occurs in places like Massachusetts, Iowa, Illinois, New York, etc. (which is wrong). Wikipedia just copies its range information from Moth Photographers Group, so it now indicates a very broad range for the species as well.
Meanwhile, with BugGuide, MPG, and Wikipedia indicating that vittata occurs much farther north than reality, Butterflies and Moths of North America (BAMONA) started accepting records of vittata from all over the place, despite some of them being dead-ringers for other species. For example, the main thumbnail on the BAMONA page here: https://www.butterfliesandmoths.org/species/Apantesis-vittata?page=2 has already been corrected to A. nais by an expert and moved to the A. nais page on BugGuide, here: https://bugguide.net/node/view/782932
In fact, nearly all the BAMONA "vittata" photos are unidentifiable at best, and clearly wrong at worst.
Check out the hindwing on this one, clearly phalerata or carlotta, and not nais or vittata: https://www.butterfliesandmoths.org/sighting_details/498894
Here's one that's clearly nais: https://www.butterfliesandmoths.org/sighting_details/902351
Another nais: https://www.butterfliesandmoths.org/sighting_details/527619
Classic carlotta: https://www.butterfliesandmoths.org/sighting_details/507248
And, as with the way they were once sorted on BugGuide, you'll notice from the thinner antennae that most of the ones on BAMONA are just females with the "reduced forewing markings" seen on females of all these species.
Of course, records "verified by BAMONA" make their way onto other websites. For example, vittata likely doesn't occur in Maryland, but check out all the classic phalerata photos listed as vittata here: https://www.marylandbiodiversity.com/viewSpecies.php?species=2496
iNaturalist now gets so many photos submitted under the name vittata that the AI suggests it left and right, even claiming "seen nearby" in places where the species doesn't exist.
So now here we are, in 2020, with all the standard online resources for moths showing a vastly over-representative range for Apantesis vittata, and the posts assigned this species name on iNaturalist popping up faster than anyone can correct them. Part of the problem is that most of the photos on iNat are just not identifiable, and people often get annoyed when you throw things back to the genus level after they think they know what species it is. But a big part of the problem though is that telling someone "vittata isn't found in your area" is a hard sell when they can look at any moth website and see apparent evidence to the contrary. A. vittata certainly might occur in places where it's not yet been recorded, but in the absence of a dissected specimen, it's hard to justify a claim of a range extension based on a photo that might be one of several species.
I don't know what the solution is to this issue, and I'm sure this isn't the only species group where this is an issue. But as someone interested in accuracy of species records, this situation is just overwhelming. Every time I decide to work through identifying these, there are just so many "vittata" to go through, and nearly all of them are either definitely wrong or probably wrong.
I'm curious what others think about this sort of problem. Is this just a feature of crowd-sourcing photo records of things that can't always be identified from photos? Is there a feature that could be added to iNat to make it harder to submit records outside the known range of a species without being really sure of your ID? All thoughts appreciated.

由使用者 paul_dennehy paul_dennehy2020年08月17日 15:54 所貼文 | 15 評論 | 留下評論

2019年03月14日

Confusing Yellow Pyraustines Demystified

The purpose of this post is to demystify the “confusing yellow Crambids” in the subfamily Pyrausinae in the United States and Canada. This is a group of moths with some difficult-to-identify species, but many are identifiable based on photos alone if you know what to look for. The species and genera discussed here are:
Hahncappsia spp
Helvibotys spp
Neohelvibotys spp
Crocidophora tuberculalis
Ecpyrrhorrhoe puralis
Paracorsia repandalis
Anania labeculalis
The first three genera are closely related and contain some extremely similar species. The last three species are superficially similar to the species in those genera, and appear to be commonly confused with them online.
Virtually every online moth ID platform has a history of major misidentifications of all these species. BugGuide was a mess until I sorted through their photos in 2017, MPG had lots of misidentifications until it was updated in 2017, and BAMONA still has quite a few misidentifications in this group as of March 2019. The first thing to look at when trying to place these species is the st line on the forewing. The following characteristics can help start the ID process:
Hahncappsia spp: Most have an st line present, but it can be faint. When present, it is always straight, not curved to parallel the terminal edge of the forewing. H. fordi and H. alpinensis, both species found exclusively in the Southwest, are very plain and lack st lines entirely, making them look more like Helvibotys spp than like other Hahncappsia.
Helvibotys spp: no st line present
Neohelvibotys spp: no st line present
Crocidophora tuberculalis: A native species to most of the East with a bold, thick, dark st line that is curved so it parallels the terminal edge of the forewing. This should make this species unmistakable. The males of this species also have a scaleless crinkled fovea on the forewing, which isn’t seen in any other species treated here. Here’s a male with the crinkled fovea: https://www.inaturalist.org/observations/18384692 And a female without it: https://www.inaturalist.org/observations/20497923
Ecpyrrhorrhoe puralis: a large bright yellow species introduced in the Southeast with faint markings overall, the st line being curved when present, but often not visible. Here’s a well-marked one: https://www.inaturalist.org/observations/4041567 And a poorly marked one: https://www.inaturalist.org/observations/817257
Paracorsia repandalis: a dull species introduced in the Northeast and upper Midwest with a curved st line, and thick smooth pm and am lines. Here’s a typical one: https://www.inaturalist.org/observations/12281430
Anania labeculalis: a southwestern species with a faint, thin, wavy st line. The lines on this species are all generally very thin and quite dark, and it can be easily separated from Hahncappsia in the area by its complete PM line on the hindwing, reaching the inner margin. Look at the visible pm line on the hindwing here; no way this should be mistaken for a Hahncappsia: https://www.inaturalist.org/observations/868592
Once you’ve eliminated A. labeculalis, E. puralis, P. repandalis, and C. tuberculalis for your moth, there are a few “easy” to identify Hahncappsia and Helvibotys you can check.
Distinctive species:
Hahncappsia coloradensis: this is a big white species of the interior mountain west and western plains, with dark brown scaling near the costa and around the reniform and orbicular spots, which looks like this: https://www.inaturalist.org/observations/16683451
Hahncappsia mellinialis: This species is bigger than any other treated here, is brown, is only found in mountains in Arizona and New Mexico (maybe west TX too?), and is more likely to be confused with an Ostrinia than a Hahncappsia. Here’s a typical specimen: https://bugguide.net/node/view/1299446/bgimage
Helvibotys pucilla, Helvibotys freemani, and Helvibotys subcostalis: these look nothing like any of the other species treated here, and can be viewed on MPG.
If you don’t have one of these “distinctive” species, placing your moth to genus gets a little trickier. This is generally what I look for:
Hahncappsia: Usually have more wavy pm lines on the FW than Helvibotys and Neohelvibotys. Other than alpinensis and fordi, usually have at least a trace of an st line on the forewing. Here are some typical Hahncappsia specimens: https://www.inaturalist.org/observations/9457573 https://www.inaturalist.org/observations/14577667
Helvibotys and Neohelvibotys: usually have smooth and very bold pm lines on the FW, and never have an st line. Here’s a typical specimen: https://www.inaturalist.org/observations/14137388
Hahncappsia alpinensis and fordi are two “non-typical” Hahncappsia that look like this: https://www.inaturalist.org/observations/19012350 The forewings look more like Helvibotys than Hahncappsia, but note the almost complete lack of markings on the hindwings, and note how faint the markings are compared to a real Helvibotys/Neohelvibotys like this: https://www.inaturalist.org/observations/14845820. H. alpinensis and fordi are best separated by genitalia where they both occur, from Arizona to west Texas. In Southern California and Nevada, only fordi occurs, and in most of Texas, only alpinensis occurs, so in many cases they can be ID’d by range.
If you have a “typical Hahncappsia”, these are your options:
In the East, you could have pergilvalis, mancalis, marculenta, neomarculenta, or neobliteralis. In the Southwest, you could have pergilvalis, mancalis, huachucalis, jaralis, pseudobliteralis, or cochisensis. In peninsular Florida, you likely have H. ramsdenalis: http://v3.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=341792
Hahncappsia mancalis: This species has the boldest and most complete st line of any of the typical Hahncappsia species. It also tends to be more tan in color (less yellow) compared to the other options. Here’s a typical example: https://www.inaturalist.org/observations/14680897
Hahncappsia pergilvalis: This species is generally paler in its base color than the others it occurs with, and its st line is usually splotchy and broken in the middle, like this: https://www.inaturalist.org/observations/16683448
Hahncappsia marculenta/neomarculenta/neobliteralis: this is the trio of eastern yellow species that is the most difficult to separate in photos. Marculenta is by far the commonest of the three, but the others are equally as widespread. Here is a typical example: https://www.inaturalist.org/observations/10186526 This species group is only differentiable based on genitalia, and specimens that have not been dissected should never be identified to the species level.
Hahncappsia huachucalis: This species is abundant in the mountains of southeastern Arizona, but doesn’t occur outside that region in the US. It’s a pretty spectacular-looking rusty brown species that isn’t easily mistaken for others in the genus in good condition: https://www.inaturalist.org/observations/10869666 It’s the most common Hahncappsia in the Chiricahua Mountains.
Hahncappsia jaralis/pseudobliteralis: This pair is the southwestern equivalent of the eastern marculenta/neomarculenta/neobliteralis group, and is also best separated based on dissection. Here is one of each that I dissected: https://bugguide.net/node/view/1457763/bgimage and https://bugguide.net/node/view/1457757/bgimage
Hahncappsia cochisensis: This is the only Hahncappsia species in the US that I haven’t personally encountered, so I can’t make many generalizations about it. It appears to be a pale yellow species with white hindwings found in southeastern Arizona: http://v3.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=287890 The plain white hindwings seem to be diagnostic.
If you have a typical Helvibotys/Neohelvibotys, then consider the following options:
In most of the East, if your moth has a dark terminal band, like this: https://bugguide.net/node/view/1422376/bgimage then you have N. neohelvialis. If your moth lacks this, and is a bit smaller, then you likely have H. helvialis, shown here: https://bugguide.net/node/view/528994/bgimage
In the Southwest, then the large ones with the dark terminal band are N. arizonensis, shown here: https://bugguide.net/node/view/1441697/bgimage, while the small ones without it are likely to be H. pseudohelvialis: https://bugguide.net/node/view/1457768/bgimage
The only other species that throws a wrench in things is N. polingi, a Neohelvibotys that lacks the dark terminal band like a Helvibotys and is found from Florida west through Texas (possibly also SE Arizona?). If you’re in the Deep South, you’ll likely need to dissect your Helvibotys-looking specimens to distinguish between the two Helvibotys species and N. polingi. Here’s a N. polingi specimen: https://www.inaturalist.org/observations/6809500
Hopefully this post provides enough information to determine which of these yellow Pyraustines are identifiable from photos and which are not. There are a lot of species involved in this group, but most can be identified if you know what to look for.

由使用者 paul_dennehy paul_dennehy2019年03月14日 02:42 所貼文 | 6 評論 | 留下評論

2018年05月07日

The Dubious Records of the Dubious Tiger Moth (Spilosoma dubia)

Of all the species of Spilosoma in the United States and Canada, none seems to be more misunderstood in online records than Spilosoma dubia. Between BugGuide, iNaturalist, Moth Photographers Group, and BAMONA, I have seen dozens of misidentified photos labeled as S. dubia, and about one real S. dubia for every ten misidentifications. For example, as of May 2018, the BAMONA page for S. dubia features photo records of Norape ovina, Hyphantria cunea, Spilosoma congrua, and Artace cribrarius, and one or two photos that may be S. dubia, but not one definitive dubia photo in the bunch.

Why is this species so often misidentified? I’d say one main reason is lack of understanding of the species’ range and abundance. S. dubia has two disjunct populations in North America. One population occurs in the Canadian Zone in boreal forest from Alberta east to New England and the Maritime Provinces. This population occurs as far south as northern Pennsylvania, where it is quite rare. The second population occurs along the Gulf Coast, from eastern Texas through Florida, and northward along the Atlantic coastal plain to North Carolina. The species is therefore absent from most of the eastern United States, occurring only in the far northern and far southern parts of the region. (Dale Schweitzer, personal communication). I’ve personally collected the species in coastal North Carolina and the Upper Peninsula of Michigan, and the series of specimens from the two populations are indistinguishable to my eye. Unfortunately, many photos of similar white moths with black spots were posted under “Spilosoma dubia” on BugGuide throughout the 2000s, and those records made their way onto the Moth Photographers Group maps at the time. That led people to believe that this was a common and widespread eastern species, which led to numerous misidentifications on BAMONA, and ultimately to a range map in the new Peterson Guide to Northeastern Moths that shows the species occurring throughout the eastern US. Now that this over-inclusive range has become so widely accepted by moth photographers, photos are frequently posted to iNaturalist identified as S. dubia that are 500+ miles out of range.

So, how does one actually identify a “real” Spilosoma dubia? Well, there are five eastern species to consider before arriving at a definitive ID of “S. dubia”, and seeing the abdomen of the specimen is essential to making an ID. If you just have a photo of the moth with its wings folded up, you probably won’t get a definitive ID.

  1. Spilosoma congrua: forewings range from pure white to moderately speckled with black. The abdomen is pure white. Front legs are yellow-orange
  2. Spilosoma latipennis: forewings are almost always pure, silky white. The abdomen is pure white. Front legs are bright pink (hence the common name).
  3. Spilosoma virginica: forewings are pure white or have a few black spots. The abdomen has bright yellow-orange sides and a row of large black spots down the back of it. Without seeing the abdomen, these could be mistaken for S. latipennis or a lightly marked S. congrua.
  4. Hyphantria cunea: forewings range from pure white to very heavily covered in black. This species is generally noticeably smaller than the Spilosoma species. The abdomen is white on the sides (never any yellow), but usually has a row of small black spots along the top of the abdomen. There is also a difference in the spurs on the front legs, which is usually not visible in photos.
  5. Spilosoma dubia: forewings are almost always moderately speckled in black, basically identical to a well-marked S. congrua. However, the abdomen has yellow along the sides and black spots along the top, like S. virginica. There are long white scales that overlay the yellow section of the abdomen though, causing the yellow to not stand out or be as bright as in S. virginica. I often describe S. dubia as a “dirty” version of S. virginica for this reason. Those white scales rub off over time, leaving the yellow more noticeable. For comparison, here is a S. dubia with the white scales on the abdomen worn off, making the yellow stand out more: http://v3.boldsystems.org/pics/_w300/LNC/06-NCCC-733%2B1147097706.jpg and here is a S. dubia with the white scales still intact, obscuring the yellow coloring: http://v3.boldsystems.org/pics/_w300/LNC/06-NCCC-732%2B1147097682.jpg The yellow is still visible in both specimens though. The front legs of S. dubia are yellow, just like most of the other species (except S. latipennis).

So essentially, if you are just going by forewing pattern, S. dubia is identical to a well-marked S. congrua, and extremely similar to a moderately marked H. cunea, and could easily be mistaken for either of those species. Only by examining the abdomen can you see the differences that separate these three. Somehow, it seems to have become common practice online to identify any Spilosomina specimen with moderately-to-heavily speckled wings as “S. dubia”, despite there being two other much more likely identifications for such specimens. If you are outside the two known ranges of S. dubia, it’s almost certain you have S. congrua or H. cunea, and even within its range, it’s usually not as common as the other two options.

In conclusion, there are a handful of definite S. dubia photo records online, which clearly show the dirty yellow on the abdomen, and all are from Texas-coastal North Carolina, or from the far northern Canadian Zone. There are many more supposed S. dubia records online from other parts of the United States, and not a single one of them shows the abdomen to confirm the ID. These records should not be trusted unless more information can be supplied. If you live in the area outside where S. dubia is known to occur, and you would like to find a specimen to expand the species’ known range, then be sure you’re getting photos of the top and sides of the abdomen when you encounter possible dubia specimens. Otherwise, your records are likely to remain “ddubious” forever.

由使用者 paul_dennehy paul_dennehy2018年05月07日 16:09 所貼文 | 3 評論 | 留下評論

2018年04月20日

Zale lunata vs. Zale minerea

Zale lunata and Zale minerea are common widespread moths in the United States and Canada, and the two are often confused. Both have multiple phenotypes, and the variation in coloration within each species is far greater than color differences between them. Here is a comparison of the forms from the Northeast:

https://tinyurl.com/y9oldr8t

You'll notice that lunata is consistently larger than minerea, but this doesn't help much when identifying photos of individual moths. The palps are also different in length, but the easiest way to tell them apart is by looking for the "double lobe" in the PM line which is present in lunata but absent in minerea. Here's an image showing this difference highlighted:

https://tinyurl.com/y73jmv3e

Of course, there are dozens of other Zales out there too, so one can't rule out every other Zale species with this rule. In particular, galbanata looks like a paler version of minerea in some of its forms, and it often gets confused with minerea (though you should never confuse it with lunata, as it lacks the bilobed PM line.) But if you're fairly certain you've got a minerea/lunata, this is a pretty consistent way to figure which one it is.

由使用者 paul_dennehy paul_dennehy2018年04月20日 21:36 所貼文 | 6 評論 | 留下評論

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