The Mormo Complex in Southern California
The taxonomy of the fascinating mormo complex of butterflies is, well, complex. In southern California, there are many distinctive populations of this group adapted to various species of wild buckwheats (Eriogonum), from the beaches to the deserts and high into the mountains. Some of these fly only in the fall; others only in spring; and some may have several broods in a typical year. Some are nearly all black on the dorsal side with relatively bold white macules, while others are golden yellow, or somewhere in between. Despite the variety in appearance, host plants and life-cycle timing, these were all thought of as a single species not so long ago. But now there are reasons to believe that there are at least four species involved, with perhaps a dozen subspecies in southern California alone.
Our knowledge of these butterflies has increased significantly thanks to rearing and genetic studies, as well as careful observation by devoted amateurs who have noted places where two or more members of the complex co-exist without apparent blending. This page is intended to give a general overview of this interesting complex. These perhaps superficially-similar butterflies reward close attention, as the differences between populations are real and they uncover a long evolutionary story that continues to unfold right here in our backyard.
From left: golden A. mormo cythera, which flies in the autumn at Big Rock Creek; spring-flying A. virgulti pratti from the Holcomb Valley near Big Bear, where it uses E. kennedyi as host; and the dark, E. wrighti-feeding "near mormo" fall-flying entity from along Wildhorse Meadows Road below Onyx Peak south of Big Bear. As distinctive as some of these are, looks alone aren't enough to identify all the various members of this complex. Timing, location and plant associations are important.
The mormo-complex in and around the Mojave desert in southern California has been described in terms of three "biotypes". According to a landmark 1991 paper by Gordon Pratt and Greg Ballmer ("Three Biotypes of Apodemia Mormo (Riodinidae) in the Mojave Desert," Journal of the Lepidopterists' Society 45(1), 1991, 46-57), these three biotypes are multiple-brooded (type 1); single-brooded and flying in the spring (type 2); and single-brooded and flying in the late summer or fall (type 3). "To determine whether these different biotypes are due to seasonal or host-related factors or to genetic differences, we reared a number of populations under similar laboratory conditions" (p. 48). They found that the three types maintained different development times under identical conditions. For instance, type 2 spring-brooded butterflies are characterized by long larval development times, from 5 to 8 months of the year. These go through the egg and pupal stages relatively quickly. Type 3 fall-brooded mormo, in contrast, have a much shorter larval stage and pass much of the year as eggs (first instar with the eggs to be precise), then develop as larvae through the summer, pupating and emerging as adults in late summer or early autumn when they mate and the females oviposit, completing the year-long cycle. The eggs of these butterflies are also larger than those of type 2. The timing of diapause and larval feeding corresonds to the patterns of dormancy and growth of the buckwheat host. For instance, the spring-flying desert subspecies mojavelimbus has a long larval development time, and the host, E. fasciculatum, usually goes dormant during the summer. When the plant resumes growing (after sufficient rainfall), the larvae may resume eating. In type 1 (multiple-brooded) populations, eggs hatched relatively quickly, and larvae developed and pupated without long periods of diapause. These butterflies could go through the life cycle two or three times per year, thanks to the availability of edible plant material for the larvae most of the year. Under identical laboratory conditions, a multiple-brooded deserti could complete the life cycle three times per year, but the type 2 and 3 butterflies, even with fresh plants available all year, persisted in completing the cycle once per year, just as in nature.
The biotype concept is helpful for grouping these populations of butterflies. In an excellent article called "Buckwheat Metalmarks" in American Butterflies magazine (Vol.19, Nos.2/3/4, Summer/Fall/Winter 2001), Gordon Pratt, John F. Emmel and Gary Bernard used the word "group" for the various populations. For example, the "mormo group" was characterized as "single-brooded, late flying (mainly August through September) populations with large eggs." That group included mormo, autumnalis, pueblo, langei, tuolumnensis, cythera, parva, and an unnamed population. Other groups are mejicanus, duryi, multiple-brooded virgulti, and single-brooded virgulti (which fly in the spring). It would be good to have a different name for the spring flyers, and for a brief time dialeuca was floated (I used it), but true dialeuca is double-brooded, so that name isn't appropriate.
So the complex can be organized like this for southern California:
One spring brood - virgulti group |
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|---|---|---|
| Butterfly | Host buckwheat | Comments |
| pratti Pratt's Metalmark |
Eriogonum kennedyi | There is a colony in the Holcomb Valley, just north of Big Bear Lake. Flies early May to mid-June. Prominent white macules. Described in Systematics pp. 795-6. My photos are from May 29th, 2009. |
| peninsularis Peninsular Metalmark |
Eriogonum wrightii ssp membranaceum | San Jacintos to Palomar Mountain and Laguna Meadows. Flies from mid-May to late June but emerges earlier some years. I found a couple of peninsularis freshly emerged in a large patch of wrightii in the Laguna Mountains near the TL on April 17, 2008, so they can emerge earlier than once thought. Because these use wrightii even where fasciculatum also grows, they are a good candidate for eventual species status. Described in Systematics, pp. 805-6. |
| davenporti Davenport's Metalmark |
Eriogonum fasciculatum | Flies April - May. The Type Locality is Walker Pass at 5300'; it is also in the Tehachapis, the Piutes, and above Jawbone Canyon and is usually found between 4000 and 6000 feet elev. Named after the estimable lepidopterist Ken Davenport. Described in Systematics, pp. 801-2. |
| mojavelimbus Ord Mountains Metalmark |
Eriogonum fasciculatum | Found early April to mid-May at the southern edge of the Mojave desert, the TL being the Ord Mountains near Hesperia. On the northern slope of the San Bernardinos to the east into Joshua Tree, these have a dark phenotype; populations north of the San Gabriels, as at Valyermo, are a blend zone with davenporti, so you see a lot of variety there. Described in Systematics, pp. 803-4. |
| dialeucoides Whitish Metalmark |
Eriogomun wrightii ssp. subscaposum | Late May to early July from Sugarloaf Mtn to Onyx Peak, south of Big Bear in the San Bernardinos. Described in Systematics, pp. 804-5. Many have searched for this metalmark in recent years without seeing it; may be extirpated. |
One fall brood - mormo group |
||
| Butterfly | Host buckwheat | Comments |
| nr mormo Mormon Metalmark (S. Bern.) |
Eriogomun wrightii ssp. subscaposum | Wildhorse Canyon and up to Onyx Peak, using same host as dialeucoides above, in some of the same places, but later in the year. Very dark; some have no orange at all. Gordon Pratt (pers. comm.) says these are an undescribed subspecies. |
| nr mormo Mormon Metalmark (Temblors, such as Cottonwood Pass) |
Eriogonum nudum var indictum | July to early October; discussed in Ken Davenport's book on Kern and Tulare Counties and in his Emmel update. Variable but many strikingly similar to langei. |
| autumnalis Autumn Metalmark |
Several late-flowering Eriogonum species | Late August to early October. Range includes southeastern California, as well as parts of Arizona, Nevada, New Mexico, and Utah. Described by the late George Austin in Systematics, pp. 561-2. |
| cythera Cythera Metalmark |
Eriogonum fasciculatum | Populations characterized by a striking overall light yellow-orange aspect extend from the northwestern San Gabriels into the desert at Mojave River Forks as far as I can tell. |
| tuolumnensis Tuolumne Metalmark |
Eriogonum fasciculatum, wrightii, microthecum and poss. kennedyi | The Mt Piños/Frazier Park area colonies flying beginning in the late summer can be called (near) tuolumnensis, though perhaps only for lack of a better name. A single-brooded mormo that flies late August through late September where pratti flies in the Holcolm Valley - and to the west as far as Santa Barbara Co. - looks similar to tuolumnensis: see Systematics p. 796. John Emmel calls it "near tuolumnensis"; there is a blend zone with nr. mormo to the southeast. I remember seeing this among normal virgulti north of Big Bear and believing it was different. In 2019, I came upon a colony of metalmarks in a wrightii patch in Lake of the Woods that was exactly as I remember the Big Bear entity. Ken Davenport has these as tuolumnensis. |
Multiple broods - mejicanus group |
||
| Butterfly | Host buckwheat | Comments |
| deserti Desert Metalmark |
Usually Eriogonum inflatum | Desert flyer with gray hindwind background and large white macules. Larvae may burrow into stalks of host desert trumpet if they need to wait out a dry spell. Flies with other mormo without blending. Where these overlap with mojavelimbus, they tend to fly earlier. |
Multiple broods - second virgulti group |
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| Butterfly | Host buckwheat | Comments |
| virgulti Behr's Metalmark |
Usually Eriogonum fasciculatum | Fairly widespread and common, from the coast into the foothills, as well as the deserts and the mountains where the host flourishes. This is what one will see on California Buckwheat in the Santa Monica Mountains, for example. |
| arenaria Sand Dunes Metalmark |
Eriogonum cinereum | Flies at Playa del Rey near LAX property with El Segundo Blues. Described in Systematics, pp. 806-7. DNA studies suggest that phylogenetically, this metalmark branched off surprisingly early and may deserve full species status. |
| nigrescens Dark Metalmark |
Eriogonum fasciculatum | Dense colony at Colton near railroad yard. Darker than nom. virgulti. It also differs in that G. Ballmer found 80 larvae on a single buckwheat plant, whereas one or two is considered normal for virgulti. Described in Systematics, pp. 796-8. Preliminary DNA testing suggests this may be the same, or nearly so, as the late summer mormo from the Sugarloaf area, but we'll have to wait and see, and it's a very strange result if it holds up. |
| virgulti Kernville/Greenhorn Mtns. entity |
E. fasciculatum, nudum, and/or wrightii | Double-brooded. Most are black like mormo. See discussion in Ken Davenport's Kern/Tulare book. |
Selected Bibliography
1859: Cajetan and Rudolf Felder, "Lepidopterologische Fragmente," Weiner Entomologische Monatschrift 3, pp.271-2. [This is where the Felders named mormo, illustrated in the next entry.]
1865: C. Felder, in Reise der österreichischen Fregatte Novara um die Erde in den Jahren 1857, 1858, 1859 unter den Befehlen des Commodore B. von Wüllerstorf-Urbair, pp.302-3 and plate 37.
1918: William Barnes, J.H. McDunnough, "Notes and New Species," Contributions to the natural history of the Lepidoptera of North America, p.75. [Deserti described.]
1927: John A. Comstock, Butterflies of California, pp.149-151.
1938: John A. Comstock, "A new Apodemia from California (Lepidopt.)," Bulletin of the Southern California Academy of Sciences, 37:129-132. [Langei described.]
1961: Paul Opler, Jerry Powell, "Taxonomic and Distributional Studies on the Western Components of the Apodemia mormo Complex (Riodinidae)," Journal of the Lepidopterists' Society 15(3), pp.145-171. [Overview, desc. ssp. tuolumnensis and dialeuca.]
1973: Ray Stanford, "Apodemia mormo near dialeuca (Riodinidae) from Montane Southern California: New for U.S.A.," Journal of the Lepidopterists' Society 27(4), pp.304-5.
1973: John F. Emmel, Thomas Emmel, The Butterflies of Southern California, pp.48-9.
1979: Gregory S. Forbes, "Description and Taxonomic Implications of an Unusual Arizona Population of Apodemia mormo (Riodinidae)," Journal of Research on the Lepidoptera 18(3), pp.201-207.
1991: Gordon Pratt, Gregory R. Ballmer, "Three Biotypes of Apodemia mormo (Riodinidae) in the Mojave Desert," Journal of the Lepidopterists' Society 45(1), pp.46-57. [landmark paper establishing criteria for sorting out populations.]
1998: John F. Emmel, Thomas Emmel, "Two New Geographically Restricted Subspecies of Apodemia mormo (Lepidoptera: Riodinidae) from the Vicinity of San Bernardino, California," Systematics of Western North American Butterflies, ed. Thomas Emmel, pp.795-800. [named pratti, nigrescens.]
1998: John F. Emmel, Thomas Emmel, Gordon Pratt, "Five New Subspecies of Apodemia mormo (Lepidoptera: Riodinidae) from Southern California," Systematics of Western North American Butterflies, ed. Thomas Emmel, pp.801-810. [named davenporti, mojavelimbus, dialeucoides, peninsularis, arenaria.]
2011: Gordon Pratt, John F. Emmel, Gary Bernard, "The Buckwheat Metalmarks," American Butterflies 19, 2/3/4 (2011), pp.4-31. [thorough overview.]
2015: Proshek, B., Dupuis, J.R., Engberg, A. et al., "Genetic evaluation of the evolutionary distinctness of a federally endangered butterfly, Lange’s Metalmark." BMC Evol Biol 15, 73 (2015). https://doi.org/10.1186/s12862-015-0354-9
2018: Ken Davenport, Butterflies of southern California in 2018: updating Emmel and Emmel's 1973 Butterflies of southern California, pp.115-124.
2018: Dupuis, Julian R., Jeffrey C. Oliver, Bryan M. T. Brunet, Travis Longcore, Jana J. Johnson, Felix A. H. Sperling, "Genomic data indicate ubiquitous evolutionary distinctiveness among populations of California metalmark butterflies," Conservation Genetics (2018) 19:1097–1108 https://doi.org/10.1007/s10592-018-1081-8