Ship-timber beetle

Atractocerus brevicornis

One of the more unusual, and enigmatic, beetles that I encountered in South Africa was this beetle in the pantropical genus Atractocerus.  Placed in the family Lymexylidae (ship-timber beetles), species in this genus look less like beetles than they do large flying ants or strange damselflies due to their highly reduced elytra that expose their greatly elongated abdomen and leave the hind wings uncovered.  The hind wings also are unusual in that they are held fan-like in repose rather than folded as in most other beetles.  Atractocerus brevicornis is the only species in the genus found in Africa (Scholtz & Holm 1985).

Adults are attracted to light at night, as was this individual that came to our ultraviolet light at Geelhoutbos farm below the Waterberg Range in Limpopo Province. Nothing is known about the biology of Atractocerus, but larvae of other genera are reported to bore into hardwoods and palm stems (Picker et al. 2002). Larvae of the genera Lymexylon and Melittomma are believed to form symbiotic associations with ambrosia fungi that grow on the walls of their galleries (Young, 2002).  Adult females deposit fungal spores in a sticky matrix when they lay their eggs, and the hatching larvae carry the spores into wood on their bodies.  The large eyes of Atractocerus, however, suggest a predatory lifestyle. The common name of the family originates from a northern European species that has in the past been a destructive pest of ship timbers.

Atractocerus species are rarely encountered and therefore, not well studied. Their evolutionary history is still unknown; however, the oldest known lymexylid fossil is a very primitive member of the genus Atractocerus preserved in 100 myo Burmese amber (Grimwold & Engel 2005). Thus, the lineage containing these beetles had already appeared by the mid-Cretaceous and may have originated as early as the Jurassic, a fact that has earned them the moniker “living fossils.” These beetles were once thought to be among the most primitive of all Coleoptera – their simple wing venation, almost undifferentiated antennae and tarsi, and naked abdomen being likened to a supposed neuropteran common ancestor. Most authors now consider the family to be most closely related to the cucujiform groups Cleroidea and Cucujoidea (Wheeler 1986, Young 2002), although some have placed it in the Elateriformia near the Lampyridae based on wing venation. Scholtz and Holm (1985) accepted a cucujiform placement but related the group to the Styopidae (twisted-winged parasites), apparently due to the similarity of their highly reduced forwings.  At the same time, they acknowledged the many morphological and behavioral differences between the two groups, the latter itself being the subject of much evolutionary debate due to disagreement about whether the reduced forwings of male stylopids are truly homologous to the elytra of Coleoptera (some have even suggested homology with the halteres of Diptera that were switched from the metathorax to the mesothorax as a result of homeotic mutation). Most authors now place this latter group in the separate order Strepsiptera.

REFERENCES:

Grimaldi, D. and M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press, New York, xv + 755 pp.

Picker, M., C. Griffiths and A. Weaving. 2002. Field Guide to Insects of South Africa. Struik Publishers, Cape Town, 444 pp.

Scholtz, C. H. and E. Holm (eds.). 1985. Insects of Southern Africa. Butterworths, Durbin, South Africa, 502 pp.

Wheeler, Q. D. 1986. Revision of the genera of Lymexylidae (Coleoptera: Cucujiformia). Bulletin of the American Museum of Natural History 183:113-210.

Young, D. K.  2002. 71. Lymexylidae Fleming 1821, pp. 261-262.  In: R. H. Arnett and M. C. Thomas [eds.], American Beetles, Volume 2, Polyphaga: Scarabaeoidea Through Curculionoidea, CRC Press, Boca Raton,880 pp.

Copyright © Ted C. MacRae 2009

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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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16 Responses to Ship-timber beetle

  1. myrmecos says:

    That’s a cool beetle, I’ve never seen one alive. I think the recent Hunt et al Science paper on beetle phylogeny placed these basally within Tenebrionoidea, although I can’t remember offhand how strongly supported that arrangement was.

    • Yes, Hunt et al. (2008) placed the Lymexyloidea basally within the Tenebrionoidea (sister clade to Cleroidea and cerylonid series) with fairly good support (pp=0.76). Interestingly, most of the lymexyloids grouped together with the mordelids and rhipiphorids – except the nominate subfamily, which fell outside of that clade!

      Monophyly of the Cucujiformia as a whole was very strongly supported.

  2. Wow! it’s certainly a very strange beetle …

  3. Aydin says:

    Missing a leg, eh?

    Do they have antennas?

    • Yep, this poor fellow has a broken right hindleg.

      Lymexylids have rather short, 11-segmented antennae that show little modification, although some species do show some sexually dimorphism. You can see the right antennae in the photo – it barely extends back to the pronotum.

  4. If you found it in the Waterberg, it is a LONG way away from any ships, so I wonder how long it took to be distributed to this area. I have not yet seen anything with a wing like that before so it is something new to me.

    • This is not a ship-infesting species. The family gets its common name from a species in northern Europe that infested ship timbers (back when ships were made of wood).

  5. Easyparadise says:

    How odd the insect is! I’ve never seen it before, even known it from books! What’s more, I absolutely cannot recognize it as a beetle!

    • Yes, it is indeed a most un-beetlelike beetle. Even in flight it looked and sounded to me more like a wasp. I was actually a little hesitant to grab it bare-fingered😉

  6. Great post. I’m jealous that you saw a live adult. I collected lymexylid larvae in a beech log (if I remember correctly) partially submerged in a stream in Fisher Old Growth forest near Ithaca. They were bizarre looking, I thought they were sawflies at first. It took the Cornell larval biology class, me included, a long time to figure out the family in which they belonged.

    • I think I’d be just as excited at finding a lymexylid larva as seeing an Atractocerus adult. They are odd – wierd things going on caudally. Of course, larvae of Atractocerus are unknown, but I’m willing to bet they are even stranger, given the greater size and oddness of the adults compared to the genera we have in North America.

      • Anonymous says:

        Oh my gosh I went outside just awhile ago 11:15 pm and I saw this strange looking bug that I have never seen before, I totally freaked out ( I’am really afraid of large bugs, don’t know why) I was in complete shock when I saw this monster looking bug, my heart was pounding so I went back inside where I’am going to stay till my boyfriend gets home. Any way I got real curious and googled big flying bugs and I looked and looked until I saw this picture and there it was this is the bug that is right now outside of my house below my porch light. I live in Tupelo, Mississippi how did this bug get here? and I know 100% that this is the bug I saw, will never forget what it looks like. thank you a really freaked out shannon l. N.

        • Relax – these beetles do not occur in the U.S., and even if they did they are completely harmless. There are many possibilities for what you actually saw, but whatever it is almost certainly poses no danger.

  7. Mary says:

    Fascinating – like a few others who have commented, I would never have guessed it was a beetle.

    I’m glad you explained in the comments that this one does not infest ship timbers, but that thought raises another question. What wood exactly do the ship-timber-infesting beetles infest? And now that there are so few wooden ships providing that particular habitat, where are those beetles found?

    Sorry – off-topic I guess, but your posts do provoke one to think and question.

    • Hi Mary. Your question is both welcome and appreciated – no need to apologize. The species of ship-timber beetle that caused problems is Hylecoetus flabellicornis, which is native to Europe and Russia and has been introduced to North America and elsewhere. In nature, these beetles are found in forest habitats, where they breed in recently dead trees, windthrows, etc. They did this for many years before man came along and started “preparing food for them” in the form of ship timbers. With that industry almost non-existent once again, the beetles are back to their forest haunts and, I suspect, doing just fine.

  8. Anonymous says:

    REVISION OF THE GENERA OF LYMEXYLIDAE (COLEOPTERA: CUCUJIFORMIA) QUENTIN D. WHEELER
    BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY Volume 183, article 2, pages 113-210, figures 1-308, tables 1-4 Issued June 13, 1986 Copyright C American Museum of Natural History 1986 ISSN 0003-0090
    Gives a description of larvae of Atractocerus, is a downloadable pdf.

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