Mastigini, Fleming, 1821

Fikáček, Martin, Skuhrovec, Jiří & Šípek, Petr, 2015, Abstracts of the Immature Beetles Meeting 2015, Acta Entomologica Musei Nationalis Pragae 55 (2), pp. 859-880 : 867-868

Larvae of Mastigini ( Staphylinidae : Scydmaeninae ): morphology and biology

Paweł JAŁOSZYŃSKI 1) & Aleksandra KILIAN 2)

1) Museum of Natural History, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland; e-mail: [e-mail] 2) Department of Biology, Evolution and Conservation of Invertebrates, University of Wrocław, Przybyszewskiego 63/77, 51-148 Wrocław, Poland; e-mail: [e-mail]

The immature stages of only about 0.4% of all known species in the large staphylinid subfamily Scydmaeninae have been described so far. However, already this tiny fraction of known larvae shows an astounding diversity of body forms and structures, making scydmaenines unique among Staphylinidae . Many onisciform larvae in this group are presumably a result of a strict specialization toward feeding on armoured oribatid or uropodine mites. The feeding technique used by these scydmaeninae larvae requires curling around the ovoid prey, which is better attained if the predator’s body is broad, short and flattened.

Some scydmaenine larvae, however, have retained a presumably ancestral, staphylininelike body form, and these typically represent non-specialist, opportunistic predators. The tribe Mastigini , distributed in the Mediterranean basin and in South Africa, is one of such groups. The larvae of Mastigini are elongate and subcylindrical, with extremely long legs and antennae. The second and third instars of Stenomastigus and Palaeostigus show uniquely modified antennae, which are composed of five and not three antennomeres. This is a result of a subdivision of the antennomere II into three secondary subunits, a phenomenon not known in any other Staphylinidae . Another unusual character of the Mastigini larvae is an “evaporation apparatus” on the frons, a structure composed of a dense patch of modified setae located over a pair of glandular openings; its function remains unknown. Mastigini are also characterized by larvae with sternal plates subdivided into several paired sclerites, lack of urogomphs, a broad spectrum of variously shaped microtrichia and modified setae on their cuticles, and long spines on the antennae.

Despite apparently specialized structures (spiny and extremely long antennae, frontal glands with the “evaporation apparatus”), it was demonstrated that the larvae of Mastigini , like the adults, are non-specialized predators that rely primarily on their palps in recognizing the prey. Therefore the function of antennal and cephalic modifications, previously hypothesized to be used in prey capture, remain unknown.