The larva of Siagona europaea Dejean, 1826: Morphology and collecting technique for a subterranean blind ‘running ant killer’ (Coleoptera, Carabidae)

Abstract

The larva of Siagona europaea Dejean, 1826 collected in the field with a new type of trap, the bait trap, is described. As an adult, this is a myrmecophagous beetle; however, until 2003, in ten years of research no larvae had been found in the field when excavating deep holes around Messor nests in clay soils, in which to place the usually employed pit fall traps. Therefore, a new type of trap was adopted, i.e. a subterranean trap positioned where the main soil crevices intersect. One larva of second instar and one of third one were studied. Most larval features are atypical of carabid beetle larvae and, in particular, the form and structure of the head appendages and the form and insertion of the urogomphi are of interest. Moreover, the larva of S. europaea is completely blind, no trace of stemmata being present in either instar. Its morphology, as well as the recording of its behaviour in the lab, point to it being a ‘runner’, exploring the subterranean crack system of clay vertisols.