Eur. J. Entomol. 105 (2): 313-328, 2008 | DOI: 10.14411/eje.2008.039

How small you can go: Factors limiting body miniaturization in winged insects with a review of the pantropical genus Discheramocephalus and description of six new species of the smallest beetles (Pterygota: Coleoptera: Ptiliidae)

Vasily V. GREBENNIKOV
Entomology Research Laboratory, Ontario Plant Laboratories, Canadian Food Inspection Agency, K.W. Neatby Bldg., 960 Carling Avenue, Ottawa, Ontario K1A 0C6, Canada; e-mail: grebennikovv@inspection.gc.ca
Institut für Spezielle Zoologie und Evolutionbiologie, Friedrich-Schiller-Universität Jena, Erbertstraße 1, D-07743 Jena, Germany

The recently described and originally monotypic genus Discheramocephalus Johnson, 2007 from the Solomon Islands is revised. Six new species are described, illustrated and keyed: Discheramocephalus brucei sp. n. (Cameroon), D. elisabethae sp. n. (Cameroon), D. mikaeli sp. n. (Tanzania), D. stewarti sp. n. (Bolivia), D. jarmilae sp. n. (Bolivia), D. minutissimus sp. n. (Indonesia). Adults of D. minutissimus have a body length of about 400-426 µm, which is at the lower limit among non-egg-parasitoid insects. Evidence is provided that an egg size large enough to produce a viable larva is the main factor limiting miniaturisation of female insects. Females and males of egg-parasitoids are able to overcome the 400 µm threshold and reach limits of 180 µm and 130 µm, respectively. Brain size is likely the second most important factor limiting miniaturisation in insects.

Keywords: Body size, miniaturization, C-value, Insecta, Pterygota, Coleoptera, Ptiliidae, Discheramocephalus, Hymenoptera, Platygastridae, Errolium, egg-parasitoids, smallest insect, description, morphology, anatomy, histology

Received: August 31, 2007; Accepted: January 2, 2008; Published: May 15, 2008

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