Calephelis Metalmark ID Notes for Arizona (Fatal, Arizona, & Wright’s)


Differences between Arizona (C. arizonensis) and Fatal (C. nemesis ssp. nemesis) in Arizona

1] Location/Habitat: Fatal- Found at various elevations & terrains throughout much of AZ. Arizona- Usually found in pine/oak canyons with intermittent streams south of Tucson at or above 3,800’ elevation. Its range closely follows the range of its main host plant, Lemmon’s Beggarticks.

2] Black Post-Median band line pattern on Forewing: Fatal- Bar 3 usually significantly higher than Bar 1. Arizona- Bar 3 about 75% of time roughly even with Bar 1 and 25% of time significantly higher. (See also the below Bar Alignment Note)

3] Median band darkness: Fatal- Usually light to dark & typically present in both its forewing & hindwing. Some in their summer form, however, have a light to medium orangish upper-wing coloration and lack darkening in their median band. Arizona- None to light & usually has no median band darkening on its hindwing. (See the below “Median Band Darkness Note” for additional discussion)

4] White fringe-marks on Forewing: Fresh Fatal- Three prominent marks (Each end & the middle), Fresh Arizona- Usually 4 to 6 with middle marks often weak & small. Some, however, have only 3 marks similar to that of a Fatal.

5] Upper-wing color: Fatal- Usually brownish, orangish brown, or orangish. Arizona- Usually reddish brown or reddish orange. Color mixes & hue overlap, however, occur between the two species. Feature helpful mainly on specimens possessing an obvious reddish or pure orangish hue. Both species can have pale areas in their PM band (area between silver & black lines) in their FW & HW that can give them a non-uniform coloration look. These whitish patches occur predominantly in their winter form (Jan. to June). Upper-wing coloration typically should be given only minor weight.

6] Size & Behavior: Arizona is slightly larger than Fatal. This is often apparent when both are in the same area or through experience. Arizona males are also much more territorial than Fatal males. They will aggressively patrol & chase other butterflies, even other species, away from their territory.

7] Silver Post-Median band line pattern on Forewing: Fatal- Bar 2 usually offset below Bar 1, but occasionally is even with it. Arizona- Bar 2 always offset below Bar 1. (Subspecies Note: In Texas & parts of New Mexico, Fatal subsp. australis is present. Its Silver Bar 1 & 2, unlike Fatal subsp. nemesis that is in Arizona, are always approximately even.)

Wright’s Metalmark (C. wrighti) is very rare in Arizona. The species is found primarily in southern California and the Baja Peninsula in Mexico. A few have been reported, however, in western Arizona along its border (Colorado River) with California and Nevada. An isolated and small population has been documented also in the mountains about 20 miles northeast of Phoenix in the Rackensack Canyon & Log Corral Canyon area. I am not aware of any other locations in Arizona it has been found. Wright’s Metalmark looks very similar to Arizona Metalmark. The two species do not appear to overlap in location. Wright’s differs slightly from Arizona Metalmark in never having a darkened median band and a fresh specimen generally having three large and prominent white fringe-marks (each end & middle) on its forewing.


Miscellaneous & Reference Info.

Bar Alignment Note: To interpret the bar alignment pattern on an extended upper forewing, an imaginary line formed by connecting its first 3 black submarginal dots on its forewing should be held approximately in a horizontal position to the identifier. Bars will often have an irregular shape (e.g. a slanted line or two joined slanted lines). Height for these bars should be taken at the center of the cell they are within. The black submarginal dots located above the bars can be used as reference as they are situated at cell center. Bar alignment pattern is usually clearer on a closed underwing.

Median Band Darkness Note: Arizona often has a “medium to darkish” chestnut to brownish upper-wing ground coloration with little or no darkening in the hindwing’s median band. Fatals, however, that have this same “medium to darkish” coloration almost always have significant median band darkening in both the forewing and hindwing. Orangish Fatals of a “light to medium” coloration with little or no median band darkening occur typically only from Spring to Fall (May-Dec.). They can look very similar to some Arizona, but often can be separated by elevation/habitat, median band pattern, size, etc. Winter-form Fatals (January-April) almost always have a darken median band that contrasts fairly sharply with a lighter base wing coloration. Both species in their winter form can have contrasting whitish patches on the outer leading edge of their forewing and hindwing that can give them a bicolor look.

Host Plant Notes: Fatal- Virgin's Bower (Clematis drummondii & ligusticifolia) & various Baccharis (e.g. Baccharis salicfolia & salicina). Arizona- Lemmon's Beggarticks (Bidens lemmonii) It is found on rocky slopes often near seeps from 4,200’ to 7,500’. Wright’s- Sweetbush (Bebbia juncea).

Reliability of ID Notes: Information in the guidebooks for identifying Calephelis present in the southwestern United States I have often found confusing and occasionally inaccurate. This arises in part from the three subspecies of Fatal in the United States (ssp. australis in Texas, ssp. nemesis in Arizona, & ssp. dammersi in California) generally being treated as having identical features when in fact differences exist.

In deriving the above notes, data from Butterflies of America was first analyzed for unique species traits. Identifications from this source are largely made by academic professionals who may perform genitalia or DNA analysis. Interesting traits from it were then tested on other data such as iNaturalist to see if they held. If they did not hold, an attempt was made to find out why (e.g. misidentification, variability, etc.). Wing shape, white fringe-marks on hindwing, and submarginal spot size on hindwing were not found very helpful. The above ID notes I found reasonably accurate, especially, when one is able to get confirmation with at least two of a species’ special features. Comments and corrections are welcomed. I also have journal posts in iNaturalist on identifying Calephelis in Texas and California.

Main Reference Sources:
"A Swift Guide to Butterflies of North America" (2017) by Glassberg
Personal observations & readings from BugGuide, iNaturalist, etc.

Posted on December 27, 2020 06:16 PM by sfrue sfrue


Great journal post, Sam!

Posted by sambiology over 3 years ago


Posted by muir almost 3 years ago

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