Clambus simsoni, from Renner (2002).

Belongs within: Coleoptera.
Contains: Staphyliniformia, Elateriformia, Bostrichoidea, Cucujiformia, Eucinetidae, Scirtidae, Derodontidae.

The Polyphaga is the largest subdivision of beetles, and accordingly diverse in morphology and habits. Its members can be distinguished from other beetles by the absence of notopleural sutures at the sides of the prothorax. They are first represented in the fossil record by the Triassic Peltosyne triassica from Central Asia (Lawrence & Britton 1991). The Jurassic Larvula cassa may represent an early aquatic polyphagan larva, but its affinities are uncertain (Sinitshenkova 2002).

A recent molecular phylogenetic analysis of Coleoptera by McKenna et al. (2015) identified a clade containing the majority of the previously recognised Scirtoidea, together with the Derodontidae, as the sister taxon to the remaining Polyphaga (two taxa previously included in Scirtoidea, Nosodendron and Jacobsoniidae, were placed in Elateriformia and Staphyliniformia respectively). Members of this clade include Declinia, a little known, phylogenetically distinctive genus of two species of probably pollenophagous beetles found in north-eastern Asia. Of the two species, D. versicolor is found in Japan whereas D. relicta is found in nearby regions of south-eastern Russia; the two species differ in body shape and the shape of the antennal segments (Bouchard 2014). Members of the families Eucinetidae, Scirtidae and Clambidae have strongly hypognathous heads that fit against the underside of the thorax at rest. In the Clambidae, the head can be deflexed to abut on the metasternum, allowing the beetle to completely roll into a ball; members of this family also have large plates on the hind coxae that cover the hind femora (Lawrence & Britton 1991). In the genera Loricaster and Clambus, the eyes are partially or completely divided by the lateral margins of the head. Clambids are minute and feed on fungal spores in leaf litter and other decaying vegetation (Lawrence & Britton 1991).

McKenna et al.'s (2015) molecular analysis also supported a sister-group relationship between the Bostrichoidea and Cucujiformia. Such a relationship had previously been suggested on the basis of the presence in members of these groups of cryptonephridial Malpighian tubules, in which the ends of the tubules are attached to the rectum (Lawrence & Britton 1991). This arrangement may function in water retention, allowing the tubules to resorb water from the beetle's waste.

Characters (from Lawrence & Britton 1991): Cervical sclerites present; prothoracic pleuron fused with trochantin, entirely concealed, forming cryptopleuron; hind wing without oblongum cell, with transverse fold never crossing MP; metepisternum usually not meeting mid coxal cavity (rare exceptions in Derodontidae); hind coxae usually motile, not dividing first ventrite; ovarioles telotrophic.

<==Polyphaga (see below for synonymy)
    |  i. s.: Peltosyne triassica LB91
    |         Larvula cassa S02
    |         Eledona Latreille 1802 L02
    |           `--*E. agricola [=Bolitophagus agricola] L02
    |         Heliotis hopei (n. d.) L09
    |--+--Staphyliniformia MW15
    |  `--+--Elateriformia MW15
    |     `--+--Bostrichoidea MW15
    |        `--Cucujiformia MW15
    `--Scirtoidea [Derodontoidea, Eucinetiformia, Eucinetoidea] MW15
         |--+--Eucinetidae MW15
         |  `--+--Scirtidae MW15
         |     `--Declinia [Decliniidae] MW15
         |          |--D. relicta Nikitsky, Lawrence et al. 1994 B14
         |          `--D. versicolor B14
         `--+--Derodontidae MW15
            `--Clambidae MW15
                 |--Sphaerothorax AY04
                 |--Loricaster MW15
                 |--Calyptomerus [Calyptomerinae] B14
                 |    |--C. alpestris Redtenbacher 1849 B14
                 |    `--C. dubius LB91
                 `--Clambus [Clambinae] B14
                      |--C. domesticus (Broun 1886) B14
                      `--C. simsoni B14

Polyphaga [Bostrichiformia, Bostrichini, Diaperialae, Heterophaga, Malacodermata, Malacodermidae, Necrophagi, Scarabaeina, Scarabaeomorpha]

*Type species of generic name indicated


[AY04] Austin, A. D., D. K. Yeates, G. Cassis, M. J. Fletcher, J. La Salle, J. F. Lawrence, P. B. McQuillan, L. A. Mound, D. J. Bickel, P. J. Gullan, D. F. Hales & G. S. Taylor. 2004. Insects ‘Down Under’—diversity, endemism and evolution of the Australian insect fauna: examples from select orders. Australian Journal of Entomology 43 (3): 216–234.

[B14] Bouchard, P. (ed.) 2014. The Book of Beetles: A lifesize guide to six hundred of nature's gems. Ivy Press: Lewes (United Kingdom).

[L02] Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des crustacés et des insectes vol. 3. Familles naturelles des genres. F. Dufart: Paris.

[LB91] Lawrence, J. F., & E. B. Britton. 1991. Coleoptera (beetles). In: CSIRO. The Insects of Australia: A textbook for students and research workers 2nd ed. vol. 2 pp. 543–683. Melbourne University Press: Carlton (Victoria).

[L09] Lea, A. M. 1909. Revision of the Australian and Tasmanian Malacodermidae. Trans. Ent. Soc. Lond. 1909 (1): 45–251, pls 2–6.

[MW15] McKenna, D. D., A. L. Wild, K. Kanda, C. L. Bellamy, R. G. Beutel, M. S. Caterino, C. W. Farnum, D. C. Hawks, M. A. Ivie, M. L. Jameson, R. A. B. Leschen, A. E. Marvaldi, J. V. McHugh, A. F. Newton, J. A. Robertson, M. K. Thayer, M. F. Whiting, J. F. Lawrence, A. Ślipiński, D. R. Maddison & B. D. Farrell. 2015. The beetle tree of life reveals that Coleoptera survived end-Permian mass extinction to diversify during the Cretaceous terrestrial revolution. Systematic Entomology 40 (4): 835–880.

[S02] Sinitshenkova, N. D. 2002. Ecological history of the aquatic insects. In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 388–426. Kluwer Academic Publishers: Dordrecht.

Last updated: 25 May 2017.

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