Beetles (Coleoptera) Duane D. McKenna* and Brian D. Farrell and Polyphaga (~315,000 species; checkered beetles, Department of Organismic and Evolutionary Biology, 26 Oxford click beetles, A reP ies, ladybird beetles, leaf beetles, long- Street, Harvard University, Cambridge, MA 02138, USA horn beetles, metallic wood-boring beetles, rove beetles, *To whom correspondence should be addressed scarabs, soldier beetles, weevils, and others) (2, 3). 7 e ([email protected]) most recent higher-level classiA cation for living beetles recognizes 16 superfamilies and 168 families (4, 5). Abstract Members of the Suborder Adephaga are largely preda- tors, Archostemata feed on decaying wood (larvae) and Beetles are placed in the insect Order Coleoptera (~350,000 pollen (adults), and Myxophaga are aquatic or semi- described species). Recent molecular phylogenetic stud- aquatic and feed on green and/or blue-green algae ( 6). ies defi ne two major groups: (i) the Suborders Myxophaga Polyphaga exhibit a diversity of habits, but most spe- and Archostemata, and (ii) the Suborders Adephaga and cies feed on plants or dead and decaying plant parts Polyphaga. The time of divergence of these groups has (1–3). 7 e earliest known fossil Archostemata are from been estimated with molecular clocks as ~285–266 million the late Permian (7), and the earliest unequivocal fossil years ago (Ma), with the Adephaga–Polyphaga split at ~277– Adephaga and Polyphaga are from the early Triassic (1). 266 Ma. A majority of the more than 160 beetle families Myxophaga are not known from the fossil record, but are estimated to have originated in the Jurassic (200–146 extinct possible relatives are known from the Permian Ma). However timing and patterns of beetle diversifi cation, (e.g., 8, 9). including the role of fl owering plants in beetle diversifi ca- tion, remain under investigation. Beetles (Order Coleoptera) comprise the largest order of animals. With an impact magniA ed by their ubiquity, the ecological importance of beetles lies chieP y in the numerous roles they play with plants and fungi, by facili- tating reproduction and decomposition, and by directly consuming plant and fungal tissues—and other con- sumers. Indeed, beetles are part of the food web in nearly every non-marine habitat. Approximately 350,000 living species have been named. Some estimates of the total number of living beetle species are in the millions. Adult beetles can be distinguished from other insects by a suite of features that suit them to a cryptic lifestyle, perhaps most notably, forewings hardened to form elytra. Elytra protect the hindwings and body from mechanical dam- age, predators, parasites, pathogens, excessive water loss, and other factors thought to constrain habitat use and longevity in other insects (Fig. 1; ref. 1). Present-day workers recognize four suborders of liv- ing beetles: Adephaga (~35,000 species; ground beetles, Fig. 1 Representative families from the four beetle suborders, clockwise from top left: Micromalthidae (Suborder tiger beetles, whirligigs, wrinkled bark beetles, and Archostemata; Photo credit: A. Wild), Cicindelidae (Suborder others), Archostemata (~35 species; reticulated beetles, Adephaga; credit: P. Naskrecki); Hydroscaphidae (Suborder telephone-pole beetles, and others), Myxophaga (~65 Myxophaga; credit: D. Maddison), and Chrysomelidae (Suborder species; minute bog beetles, skiB beetles, and others), Polyphaga; credit: P. Naskrecki). D. D. McKenna and B. D. Farrell. Beetles (Coleoptera). Pp. 278–289 in e Timetree of Life, S. B. Hedges and S. Kumar, Eds. (Oxford University Press, 2009). HHedges.indbedges.indb 227878 11/28/2009/28/2009 11:27:30:27:30 PPMM Eukaryota; Metazoa; Arthropoda; Insecta; Coleoptera 279 Pyrochroidae-1 141 Pythidae 119 Salpingidae-1 97 Melandryidae-1 144 Tetratomidae-1 121 Trictenotomidae 85 Scraptiidae-1 135 Melandryidae-2 113 Scraptiidae-2 78 91 Boridae 137 Oedemeridae Tetratomidae-2 139 Perimylopidae 110 Melandryidae-3 Zopheridae-1 75 174 Pyrochroidea-2 175 Monommatidae 160 Salpingidae-2 172 Mycetophagidae 140 Tenebrionidae-1 Tenebrionoidea-1 Polyphaga 56 Melandryidae-4 112 158 Stenotrachelidae Zopheridae-2 142 43 Salpingidae-3 Anthicidae-1 129 Aderidae 92 Tenebrionidae-2 38 Tenebrionidae-3 Meloidae 114 Anthicidae-2 36 87 66 Anthicidae-3 Ciidae 30 Rhipiphoridae 53 Lymexylidae-1 99 28 Mordellidae Lymexylidae-2 Lymexyloidea-1 (continued on next page) Tenebrionoidea-2 P Triassic Jurassic Cretaceous Pg Ng Lymexyloidea-2 PZ MESOZOIC CENOZOIC 250 200 150 100 50 0 Million years ago Fig. 2 Continues HHedges.indbedges.indb 227979 11/28/2009/28/2009 11:27:33:27:33 PPMM 280 THE TIMETREE OF LIFE (continued from previous page) Sphindidae Corylophidae 126 Endomychidae-1 103 Endomychidae-2 65 Endomychidae-3 94 54 Latridiidae 1 - Coccinellidae a e d 79 i 19 Endomychidae-4 o J u c Alexiidae u C 32 Cerylonidae-1 169 Bothrideridae-1 149 Bothrideridae-2 98 Discolomatidae 80 Bothrideridae-3 Cerylonidae-2 Melyridae-1 145 27 Prionoceridae 127 1 - a a Melyridae-2 g e 100 a d h i p o y r Trogossitidae-1 l e l 88 o P Cleridae C 74 Trogossitidae-2 2 - 55 a Byturidae e d i 170 o J Biphyllidae u c 109 2 - u 44 a C Phloiophilidae e d i o Trogossitidae-3 r e l Erotylidae C 84 Helotidae 167 72 Protocucujidae 49 Monotomidae 3 Nitidulidae - 13 a e d Laemophloeidae i o J 45 173 u c Propalticidae u 138 C 76 Phalacridae Cryptophagidae 61 Passandridae 161 Cucujidae (continued on next page) P Triassic Jurassic Cretaceous Pg Ng PZ MESOZOIC CENOZOIC 250 200 150 100 50 0 Million years ago Fig. 2 Continues HHedges.indbedges.indb 228080 11/28/2009/28/2009 11:27:33:27:33 PPMM Eukaryota; Metazoa; Arthropoda; Insecta; Coleoptera 281 (continued from previous page) Megalopodidae-1 147 31 Cerambycidae-1 131 Cerambycidae-2 148 Orsodacnidae-1 118 Vesperidae 26 Megalopodidae-2 71 Orsodacnidae-2 Chrysomeloidea-1 Cerambycidae-3 41 108 Disteniidae Chrysomelidae-1 Cerambycidae-4 Curculionidae-1 Ithyceridae 165 Brentidae-1 128 164 Curculionidae-2 159 Brentidae-2 Polyphaga 106 Caridae Brentidae-3 20 157 89 Curculionidae-3 143 Brentidae-4 Belidae Curculionoidea 64 Anthribidae-1 171 Anthribidae-2 Nemonychidae-1 48 166 Attelabidae 162 Nemonychidae-2 12 35 Chrysomelidae-2 Silvanidae 60 Phloeostichidae Chrysomeloidea-2 (continued on next page) Cucujoidea-4 P Triassic Jurassic Cretaceous Pg Ng PZ MESOZOIC CENOZOIC 250 200 150 100 50 0 Million years ago Fig. 2 Continues Adephaga are distinctive in having abdominal stern- Distinctive features include respiration via a plastron ite II divided by the metacoxae. Distinctive features of (adults), and tracheal gills (larvae). Pupation occurs Archostemata include fusion of the labrum to the head inside the last larval exuvium in Powing water. Polyphaga capsule, A ne scales on the elytra (absent in Crowsoniella, are distinctive in having presternal cervical sclerites, and Micromalthus, and Sikhotealinia), and rolling of the the propleura internalized (5, 10). tips of the wings (not folding) when tucking under the While relationships among the four beetle suborders elytra (a similar mechanism is found in Myxophaga). have long been controversial (8, 11, 12), an arrangement Myxophaga are highly specialized for aquatic life. in which the Archostemata diverge earliest, Myxophaga HHedges.indbedges.indb 228181 11/28/2009/28/2009 11:27:34:27:34 PPMM 282 THE TIMETREE OF LIFE (continued from previous page) Lycidae 86 Lampyridae 73 Cantharidae Elateridae-1 132 Elateridae-2 154 70 122 Phengodidae Rhagophthalmidae 102 Elateridae-3 130 Drilidae 51 83 Elateroidea 153 Elateridae-4 Omalisidae 47 Eucnemidae 96 Throscidae Telegeusidae 95 34 Omethidae Dascillidae 163 Rhipiceridae 101 69 Byrrhidae Dascilloidea Nosodendridae Polyphaga Byrrhoidea-1 10 Ptilodactylidae 29 117 Callirhipidae Bostrichoidea-1 93 Chelonariidae 168 Elmidae-1 151 82 Elmidae-2 23 Eulichadidae 58 133 Byrrhoidea-2 Psephenidae Limnichidae 107 Dryopidae Buprestidae 14 59 Heteroceridae Buprestoidea Anobiidae-1 Byrrhoidea-2 52 Bostrichidae-1 146 Anobiidae-2 120 22 Bostrichidae-2 9 Dermestidae Bostrichoidea-2 (continued on next page) P Triassic Jurassic Cretaceous Pg Ng PZ MESOZOIC CENOZOIC 250 200 150 100 50 0 Million years ago Fig. 2 Continues HHedges.indbedges.indb 228282 11/28/2009/28/2009 11:27:34:27:34 PPMM Eukaryota; Metazoa; Arthropoda; Insecta; Coleoptera 283 (continued from previous page) Scarabaeidae-1 67 Glaphyridae 150 Ochodaeidae 50 Scarabaeidae-2 152 Glaresidae 115 81 Hybosoridae 40 Scarabaeidae-3 Lucanidae Scarabaeoidea 134 8 Ceratocanthidae 124 Bolboceratidae 105 Passalidae 125 Trogidae Staphylinidae-1 37 Staphylinidae-2 7 77 25 Silphidae 16 Staphylinidae-3 Staphylinoidea-1 Hydrophilidae Polyphaga Leiodidae 104 Hydrophiloidea-1 6 Agyrtidae Hydraenidae 18 Ptilidae Staphylinoidea-2 Histeridae 63 Sphaeritidae 5 42 15 Synteliidae 4 Scydmaenidae Hydrophiloidea-2 Clambidae 39 3 Eucinetidae Staphylinoidea-3 Derodontidae Scirtoidea-1 Decliniidae 116 Derodontoidea Scirtidae (continued on next page) Scirtoidea-2 P Triassic Jurassic Cretaceous Pg Ng PZ MESOZOIC CENOZOIC 250 200 150 100 50 0 Million years ago Fig. 2 Continues and Polyphaga are united as closest relatives, and rearrangements of the thorax and associated muscula- Adephaga is the closest relative of the group comprising ture in Adephaga, Myxophaga, and Polyphaga (10). Myxophaga and Polyphaga, has emerged as the prevail- Until recently, phylogenetic analyses of molecular ing hypothesis based on morphology (13, 14). Characters data were largely focused on subgroups of the Order supporting this hypothesis include reduced segmenta- Coleoptera, for example, individual superfamilies tion in the legs of larval Myxophaga and Polyphaga, and or families. A few such studies, all employing DNA HHedges.indbedges.indb 228383 11/28/2009/28/2009 11:27:34:27:34 PPMM (continued from previous page) Amphizoidae 155 Dytiscidae-1 90 2 Dytiscidae-2 68 Hygrobiidae 111 Aspidytidae 21 Noteridae 46 Haliplidae 33 11 Gyrinidae Adephaga 1 Rhysodidae+Carabidae-1 Brachinidae 24 156 Carabidae-2 136 Trachypachidae 123 Carabidae-3 Torridincolidae 57 Hydroscaphidae 17 Cupedidae 62 Myxophaga Sphaeriusidae + Archostemata P Triassic Jurassic Cretaceous Pg Ng PZ MESOZOIC CENOZOIC 250 200 150 100 50 0 Million years ago Fig.