Coleoptera

     |||||||||||| Tshekardocoleidae  
     |
     |  ========= Polyphaga  (scarabs, fireflies, ladybirds, weevils, etc.) 
     |  |
<<===|  |  ====== Archostemata 
     ===|  |
        ===|  === Myxophaga 
           ===|
              === Adephaga  (ground beetles, tiger beetles, whirligigs, etc.) 

Containing clade(s): Endopterygota

Table of Contents

Introduction

Characteristics of Coleoptera

The Suborders of Coleoptera

Discussion of Phylogenetic Relationships

Sources of Information on the Internet

References

The oldest beetle fossils are from the Lower Permian (about 265 million years old; Ponomarenko, 1995); since then the group has diversified into many different forms. They range in size from minute featherwing beetles (Ptiliidae), adults of which are as small as 0.3 mm long, to the giant Goliath and Hercules beetles (Scarabaeidae), which can be well over 15 cm. While most species are phytophagous, many are predacious, or fungivores, or are parasitoids. They communicate to one another in many ways, either by use of chemicals (e.g. pheromones), sounds (e.g. stridulation), or by visual means (e.g. fireflies). They live in rainforest canopies, the driest deserts, in lakes, and above treeline on mountains.

In one sense the most unusual property of beetles is not some aspect of their structure or natural history, but their sheer number. There are more known species of Coleoptera than any other group of organisms, with over 350,000 described species. Perhaps the most famous quote about beetles comes from the great population geneticist J.B.S. Haldane, who was asked what might be learned about a Creator by examining the world. His response: "an inordinate fondness for beetles" (Fisher, 1988).

Characteristics of Coleoptera

Other derived characteristics of beetles are:

• hind wings folded under elytra, with reduced venation
• hind two thoracic segments (mesothorax+metathorax=pterothorax) broadly connected with abdomen, so that the primary functional units of body are head / prothorax / pterothorax + abdomen, rather than the more typical head / thorax / abdomen of many other insects.
• genitalia retracted into abdomen
• adult antenna with 11 articles

The Suborders of Coleoptera

Polyphaga is by far the largest suborder, containing 85% of the known species, including rove beetles, scarabs, stag beetles, metallic wood-boring beetles, click beetles, fireflies, blister beetles, mealworms, ladybirds, leaf beetles, longhorn beetles, and weevils. Many are phytophagous. Adephaga includes ground beetles, tiger beetles, predacious diving beetles, and whirligig beetles; most adephagans are predacious. Myxophaga is a small suborder, containing less than 100 known species, whose members are small or minute, and associated with hygropetric habitats, drift material, or interstitial habitats among sand grains. Archostemata contains several families of beetles, most associated with wood; members of this family are somewhat similar to some of the earliest, Paleozoic beetle fossils.

Discussion of Phylogenetic Relationships

There are several competing hypotheses regarding subordinal relationships. The two most widely discussed differ most strikingly in their placement of the suborder Polyphaga: this suborder is either the sister group of Myxophaga (Crowson, 1960, 1981; Machatschke, 1962; Klausnitzer, 1975), or the sister group of all remaining beetles (Lawrence and Newton, 1982; Kukalová-Peck and Lawrence, 1993), as shown in the following two figures:

     ========= Archostemata               ========= Polyphaga
     |                                    |
     |  ====== Adephaga                   |  ====== Archostemata
 ====|  |                             ====|  |
     ===|  === Myxophaga                  ===|  === Myxophaga
        ===|                                 ===|
           === Polyphaga                        === Adephaga  

"Polyphaga+Myxophaga" hypothesis     "Basal Polyphaga" hypothesis

Evidence for the alternative hypothesis, that Polyphaga is the sister group to remaining beetles, is based primarily on characters of wing structure, and on the loss of the cervical sclerites in the three suborders other than Polyphaga (Lawrence and Newton, 1982; Kukalová-Peck and Lawrence, 1993).

Resolution of these relationships await an analysis of all available morphological data, as well as the gathering of molecular information. Even still, the relationships will not be easy to uncover, as groups have had a long independent history since their separation in the Permian and earliest Triassic.

The composition of the clade Coleoptera is not in dispute, with the exception of the twisted-wing parasites, Strepsiptera. These odd insects have been regarded as related to the beetle families Rhipiphoridae and Meloidae, with which they share first instar larvae that are active, host-seeking triungulins and later instar larvae that are endoparasites of other insects (Crowson, 1981), or as the sister group of beetles (e.g. Kukulová-Peck and Lawrence, 1993), or more distantly related to insects (see further discussion in Strepisptera).

Sources of Information on the Internet

• Institut National Agronomique Paris-Grignon, Coleoptagro pages. (En Français.) Includes keys to families, descriptions of families, etc.
• Coleoptera families (INBIO, Costa Rica)
• Coleoptera collections (Colorado)
• Los Lamelicornios de Costa Rica
• Warren Brigham's page on Aquatic Coleoptera on the Net

References

Arnett, R.H. 1973.  The Beetles of the United States (A manual 
          for identification).  The American Entomological Institute, 
          Ann Arbor, Michigan.

Arnold'di, L.V., V.V. Zherikhin, L.M. Nikritin, and A.G. Ponomarenko 
          (eds.). 1977. Mezozoiskie Zhestkokrylye.  Akademiya 
          Nauk SSSR, Trudy Paleontologicheskogo Instituta, Vol. 
          161. Nauka Publishers, Moscow.

Arnold'di, L.V., V.V. Zherikhin, L.M. Nikritin, and A.G. Ponomarenko 
          (eds.). 1992. Mesozoic Coleoptera.  Smithsonian Institution 
          Libraries, Washington, D.C. (English translation of 
          Arnold'di et al., 1977.)

Boving, A.G. and F.C. Craighead. 1931. An illustrated synopsis 
          of the principal larval forms of the order Coleoptera. 
          The Brooklyn Entomological Society, Brooklyn, N.Y.

Crowson, R.A. 1955. The natural classification of the families 
          of Coleoptera. N. Lloyd, London.

Crowson, R.A. 1960. The phylogeny of Coleoptera.  Annual Review 
          of Entomology, 5:111-134.

Crowson, R.A. 1981. The biology of the Coleoptera. Academic Press, 
          London.

Fisher, R.C. 1988.  An inordinate fondness for beetles.  Biological 
          Journal of the Linnean Society, 35:313-319.

Hlavac, T.F. 1972. The prothorax of Coleoptera: origin, major 
          features of variation. Psyche 79(3): 123-149.

Hlavac, T.F. 1975. The prothorax of Coleoptera: (Except Bostrichiformia 
          - Cucujiformia). Bulletin of the Museum of Comparative 
          Zoology 147(4): 137-183.

Joy, N.H. 1976. A practical handbook of British beetles. E. W. 
          Classey, Faringdon, England.

Kirejtshuk, A.G. 1992. Evolution of mode of life as the basis 
          for division of the beetles into groups of high taxonomic 
          rank.  Pp. 249-261 in M. Zunino, X. Bellés and M. Blas 
          (eds.), Advances in Coleopterology.  European Association 
          of Coleopterology, Barcelona.

Klausnitzer, B. 1975. Probleme der Abgrenzung von Unterordnungen 
          bei den Coleoptera.  Entomologische Abhandlungen staatliches 
          Museum für Tierkunde in Dresden, 40:269-275.

Kukalová-Peck, J. and J.F. Lawrence.  1993.  Evolution of the 
          hind wing in Coleoptera.  The Canadian Entomologist, 
          125:181-258.

Lawrence, J.F., and Britton, E.B. 1994.  Australian Beetles. 
          Melbourne University Press, Carlton, Victoria.

Lawrence, J.F., and A.F. Newton, Jr. 1982.  Evolution and classification 
          of beetles.  Annual Review of Ecology and Systematics, 
          13:261-290.

Lawrence, J.F., and A.F. Newton, Jr. 1995.  Families and subfamilies 
          of Coleoptera (with selected genera, notes, references 
          and data on family-group names).  Pp 779-1006 in Pakaluk 
          and Slipinski (1995).

Lawrence, J.F., S.A. Slipinski, and J. Pakaluk. 1995.  From Latreille 
          to Crowson: a history of the higher-level classification 
          of beetles. Pp 87-154 in Pakaluk and Slipinski (1995).

Machatschke, J.W. 1962.  Bemerkungen zum System der Coleoptera. 
          Tag. Ber. Dtsch. Akad. Landwiss. Berl. 45:121-137.

Pakaluk, J. and S.A. Slipinski (eds.)  1995.  Biology, Phylogeny, 
          and Classification of Coleoptera.  Papers Celebrating 
          the 80th Birthday of Roy A. Crowson.  Muzeum i Instytut 
          Zoologii PAN, Warszawa.

Ponomarenko, A.G. 1969.  Historical development of the Coleoptera 
          - Archostemata.  Trudy Paleontologicheskogo Instituta 
          Akademiya Nauk SSSR, 125:1-240. [In Russian]

Ponomarenko, A.G. 1971. The geological history and evolution 
          of beetles.  Proc. Int. Congr. Entomol., 13th, Moscow, 
          1: 281.

Ponomarenko, A.G. 1995.  The geological history of beetles.  
          Pp. 155-171 in Pakaluk and Slipinski (1995).

Smith, S.G. and N. Virkki.  1978. Coleoptera. Animal Cytogenetics, 
          volume 3, Insecta 5. Gebrüder Borntraeger, Berlin.

White, R.E. 1983. A field guide to the beetles of North America. 
          Houghton Mifflin, Boston.

About this page

Page copyright © 1995 David R. Maddison
First online 16 November 1994
Last modified 9 February 1996
This is the 2309th access of this page since 19 November 1995

Title Illustrations

• Blister beetle (Meloidae, Polyphaga). U.S.A.: Arizona.
• Tenomerga concolor (Cupedidae, Archostemata). Canada: Ontario: Burlington.
• Hydroscapha natans (Hydroscaphidae, Myxophaga). U.S.A.: Arizona: Sycamore Canyon.
• Bembidion inaequale (Carabidae, Adephaga). Canada: Alberta: Gull Lake.