Desmiphora hirticollis: Crypsis or Mimicry?

During my stay in Corrientes, Argentina last month, I was invited to spend the day with a colleague at his “camp” in Paso de la Patria. Located on the banks of the massive Rio Paraná at its junction with the Rio Paraguay, this small resort community boasts large tracts of relatively intact “Selva Paranaense,” which together with the Atlantic Forest in southeastern Brazil forms the second largest forest ecozone in South America outside of the Amazon. As my colleague skillfully prepared matambre, chorizo, and vacío (typical cuts of meat in Argentina) on the parilla (wood grill) at his camp, I explored the surrounding forest for insects. Early April is late in the season, and with generally droughty conditions in the area for the past several months there were few insects to be found. My luck improved, however, when I came upon a small area with stacks of fresh cut logs from recent wood cutting operations scattered through the area. Wood boring beetles (families Buprestidae and Cerambycidae) are often attracted to such wood piles, so approached each one slowly to look for day-active species of these beetles. After inspecting several piles without seeing anything on them, I began carefully turning over the logs to look for nocturnal species that tend to hide on the undersides during the day. Shortly I came across this highly cryptic species of cerambycid, and further searching revealed a fair number of these beetles hiding within the dozen or so log piles that I examined.

Desmiphora hirticollis on freshly cut guayabi (Patagonia americana) | Corrientes Prov., Argentina

I instantly recognized the genus as Desmiphora, an exclusively New World genus characterized by the presence of fasciculate tufts (or “pencils”) of erect or suberect hairs. Most of its nearly 50 species occur in Brazil, but two species extend as far north as southern Texas (Giesbert 1998). One of these is Desmiphora hirticollis, a widespread species found as far north as Corpus Christi, Texas and as far south as Bolivia and Argentina. I thought these beetles looked an awful lot like that species, and I later confirmed its identity as such due to its piceous (glossy brownish black) integument and the presence of small black pencils just before the elytral apices.

Adults are nearly impossible to see from overhead due to cryptic coloration…

The wood piles contained logs from several tree species, but all of the beetles that I encountered were on logs of guayaibi (Patagonula americana), a member of the family Boraginaceae and a characteristic component of Selva Paranaense (also an important timber species in Argentina). The number of individuals that I found and their occurrence only on guayaibi suggests it serves as a larval host for the beetle. Duffy (1960) described the larva from specimens collected out of Sapium sp. (family Euphorbiaceae), but in Texas this species is collected most often on Cordia spp. and Ehretia anacua (Rice et al. 1985)—both in the family Boraginaceae—with adults having been reared from Cordia eleagnoides (Chemsak & Noguera 1993).

…while the hair tufts may function in obscuring the body outline…

It seems obvious that coloration of the beetle and its pencils of hair function in crypsis. From overhead the beetles are almost impossible to discern as they sit motionless on the similarly colored bark of their host trees. Even in profile or oblique views where the body becomes somewhat more visible, the pencils seem to break up and obscure the outline of the body. I wonder, however, if crypsis is the only function of the pencils—Belt (2004) described the strong resemblance of another species in the genus, D. fasciculata—a similarly penicillate species, to short, thick, hairy caterpillars (insectivorous birds often refuse to prey upon hairy species of caterpillars). That species can be seen sitting openly on foliage during the day, while D. hirticollis seems to be strictly nocturnal; however, cryptic and mimetic functions need not be mutually exclusive, so perhaps for this species the pencils function a little for both.

…or perhaps even mimicking ”hairy” caterpillars.

REFERENCES:

Belt, T. 2004. The Naturalist in Nicaragua. Project Guttenberg eBook.

Chemsak, J. A. & F. A. Noguera.  1993.  Annotated checklist of the Cerambycidae of the Estacion de Biologia Chamela, Jalisco, Mexico (Coleoptera), with descriptions of new genera and species.  Folia Entomológica Mexicana 89:55–102.

Duffy, E. A. J. 1960. A Monograph of the Immature Stages of Neotropical Timber Beetles (Cerambycidae). British Museum of Natural History, London. 327 p.

Giesbert, E. F. 1998. A review of the genus Desmiphora Audinet-Serville (Coleoptera: Cerambycidae: Lamiinae: Desmiphorini) in North America, Mexico and Central America. Occasional Papers of the Consortium Coleopterorum 2(1): 27–43.

Rice, M. E., R. H. Turnbow, Jr. & F. T. Hovore. 1985. Biological and distributional observations on Cerambycidae from the southwestern United States (Coleoptera). The Coleopterists Bulletin 39(1):18–24.

Copyright © Ted C. MacRae 2012

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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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13 Responses to Desmiphora hirticollis: Crypsis or Mimicry?

  1. At first glance I mistook it for a moth!

  2. Troy Bartlett says:

    Wow, awesome camouflage. I really had to stare at the first photo for a few seconds to figure out what I was looking at.

    • I almost missed the first one I found – I hadn’t seen anything yet and so wasn’t really expecting to either until this one moved. I wonder how many I missed before this one!

  3. Dave says:

    Pretty impressive array of defences. If the tufts of hairs are barbed and dislodge, maybe they entangle the mandibles of patrolling ants like those of polyxenid millipedes?

    At first I was also impressed that the Boraginaceae, better known for borage, Siberian buglosses, and forget-me-nots, also grew into trees. But I thought Ehretia looked familiar and realized that I had sample E. acuminata in Australia. Another Monday morning duh moment.

    • I don’t think the hairs have such offensive capabilities – at least I’ve never noticed them detaching when handled.

      I didn’t even make the connection with forget-me-nots – interesting.

  4. Ted, check out my picture of D. fasciculata here: http://www.facebook.com/photo.php?fbid=1518346728333&l=497993880e
    I also noticed it very much resembles some local caterpillars. I didn´t know this was published. Thanks for the reference. I find these on live plants (or maybe dying?) and maybe that is why they are not cryptic like yours seems to be.

    • Not only is that a great photo, but it’s quite interesting that you independently speculated it to be a caterpillar mimic. The fact that D. fasciculata is diurnal and found on foliage makes a stronger case for mimicry rather than crypsis for that species.

  5. Margarethe says:

    What works, works, a little of both it seems – and labeling is a purely human problem. Well spotted and photographed!

    • Thanks Margarethe. Labels may be a human construct, but they are the only way I can make sense of anything. I think I’m inclined to go more crypsis for this species.

  6. I have a soft spot for hairy cerambycids and this one definitely fits the bill! I collected in Chile several years ago and would wait by woodpiles at dusk and watch the bycids fly in. Beautiful pictures! Thanks so much for sharing!

    • Thanks IBB – I think all ‘bycids are cool, but yes this one is really something. I only wish it had been a species other than one that also occurs in the U.S. ;P

  7. James C. Trager says:

    Convergent crypsis, I would say.

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