“Rare jewel beetles discovered in Mexico by team of scientists!”

I hope you’ll excuse the hyperbolic title, but such has been my impression with some of the headlines I’ve seen recently in the popular media regarding newly described insect taxa in various parts of the world. The “discovery” of new species in far away, tropical lands sounds exciting and ground-breaking to many people, who envision teams of scientists wearing pith helmets and cargo shorts machete-slashing their way through miles of virgin forest before stumbling into a secret biodiversity hot-spot, their weeks of toil and sweat finally paying off by becoming the first white men to lay eyes upon a bounty of strange, exotic, never-before-seen creatures. In reality, new species of insects are not at all hard to find—in fact, depending on where you go it can be downright easy. Admittedly the chances are greater in the tropics, where many areas remain little explored, but even in well-studied North America new species turn up regularly. This includes popularly collected beetles in the very well-studied eastern U.S., where I’ve already described one new jewel beetle (family Buprestidae) and one new longhorned beetle (family Cerambycidae) from right here in my home state of Missouri (MacRae 2000, 2003) and am in the process of describing another new jewel beetle. No, finding new species is easy—recognizing them as such is the hard part. That’s not to say that new species cannot be recognized when first encountered, but I suspect that a majority of new insect species aren’t actually “discovered” until they’ve been brought back from the field, curated, and sat in a cabinet for years or decades—unrecognized for what they really are due to resemblance to known species until somebody comes along and examines them more critically.

Such is the case with two jewel beetle species that Chuck Bellamy and I describe in a paper just published in The Pan-Pacific Entomologist (MacRae & Bellamy 2013). I joined Chuck on several trips to Mexico in 1992 and again from 2004–2006 to explore the tropical thorn woodlands in the southern states of Oaxaca, Puebla, Guerrero and Michoacán. Jewel beetle diversity is high in these still relatively intact woodlands, with a number of new species already having been described from the area in recent years, and all-told we collected well over 100 species. At least a dozen or more of these look to be new, and considering that the Mexican jewel beetle fauna as a whole includes more than 800 known species the actual number could greatly exceed 1,000. The two described in this most recent paper resemble the common, widespread species Actenodes calcaratus. This big, beautiful jewel occurs from the southwestern U.S. through Mexico and Central America to northern South America, developing as larvae in dead wood of a variety of fabaceous hosts. We collected several of what we thought was this species during our trips, but a number of subtle but consistent differences in punctation and surface sculpturing emerged as we began comparing them more critically against A. calcaratus from other locations. The coup de grâce, however, was the coloration of the male face—normal bronze in A. calcaratus (Fig. 5) and similar to the female (Fig. 6), but flash-green in male A. scabrosus (Fig. 2) and green-violaceous in male A. michoacanus (Fig. 8). It’s quite remarkable that both of these species differ from their more widespread relative by subtle morphological characters but such striking sexually dimorphic facial coloration, and we subsequently found a similar situation with another species in the genus (A. undulatus) that otherwise bears little resemblance to A. calcaratus.

Figs. 1–9. Actenodes spp. 1–3. Actenodes scabrosus. 1–2. Male holotype. 1. Dorsal habitus. 2. Frontal view. 3. Female paratype (Guerrero). 4–6. A. calcaratus. 4–5. Male (MEXICO, Guerrero, Hwy 95, 5 km S Milpillas, 7.vii.1992, "big dead tree", G. H. Nelson [FSCA]). 4. Dorsal habitus. 5. Frontal view. 6. Female (MEXICO, Hwy 95, 2 km S Milpillas, 6.vii.1992, on Acacia farnesiana, G. H. Nelson [FSCA]), frontal view. 7–9. A. michoacanus. 7–8. Male holotype. 7. Dorsal view. 8. Frontal view. 9. Female paratype, frontal view. All scale bars = 5 mm.

Figs. 1–9. Actenodes spp. 1–3. Actenodes scabrosus. 1–2. Male holotype. 1. Dorsal habitus. 2. Frontal view. 3. Female paratype (Guerrero). 4–6. A. calcaratus. 4–5. Male (MEXICO, Guerrero, Hwy 95, 5 km S Milpillas, 7.vii.1992, “big dead tree”, G. H. Nelson [FSCA]). 4. Dorsal habitus. 5. Frontal view. 6. Female (MEXICO, Hwy 95, 2 km S Milpillas, 6.vii.1992, on Acacia farnesiana, G. H. Nelson [FSCA]), frontal view. 7–9. A. michoacanus. 7–8. Male holotype. 7. Dorsal view. 8. Frontal view. 9. Female paratype, frontal view. All scale bars = 5 mm.

In the case of both of these new species, the first specimens were actually collected more than 40 years ago but remained “hidden” among specimens of A. calcaratus until we examined the collections containing them more closely. While it might seem that the striking male facial coloration both of these species exhibit should have resulted in their quick recognition as undescribed species, even seemingly obvious characters such as this can be overlooked when an otherwise great resemblance to a common, widespread species prevents their critical examination.

REFERENCES:

MacRae, T. C. 2000. Review of the genus Purpuricenus Dejean (Coleoptera: Cerambycidae) in North America. The Pan-Pacific Entomologist 76(3):137–169.

MacRae, T. C. 2003. Agrilus (s. str.) betulanigrae MacRae (Coleoptera: Buprestidae: Agrilini), a new species from North America, with comments on subgeneric placement and a key to the otiosus species-group in North America. Zootaxa 380:1–9.

MacRae, T. C. & C. L. Bellamy. 2013. Two new species of Actenodes Dejean (Coleoptera: Buprestidae) from southern Mexico, with distributional and biological notes on Buprestidae from Mexico and Central America. The Pan-Pacific Entomologist 89(2):102–119.

Copyright © Ted C. MacRae 2013

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About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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2 Responses to “Rare jewel beetles discovered in Mexico by team of scientists!”

  1. Jon Quist says:

    For me, Jewel beetles have been, for the most part, hard to come by. I enjoy collecting the Acm. and Agrilus, but those two and Anthaxia are usually what I find. Because so many jewels often require extensive collecting techniques, I would imagine the actual number of undescribed or undiscovered species (many simply very rare) could be higher than anyone would bid.

    • Collecting jewels in the west is tricky – you need to know host plants and timing. It’s easy to waste a lot of time finding nothing unless you do your homework. In the east it’s easier but still requires a sense of which situations look promising. Never pass up a fresh woodpile or standing recently died tree. Most importantly – beat! You can beat 100 trees and get nothing and then collect 12 specimens of something great off of tree #101. Again, learning which hosts are likely to harbor which species is key.

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