First insight into detailed morphology of monotomids, with comments on chaetotaxy and life history based on myrmecophilous Monotoma angusticollis.

This paper is the first morphological description of the developmental stages of a representative species of Monotomidae family. The paper describes the external structures of the early (L1) and last (L3) larval instars of the Euro-Siberian myrmecophilous monotomid beetle Monotoma angusticollis (Gyllenhall) (Coleoptera Monotomidae), associated with the Formica rufa species group. This is also the first complete, detailed and richly illustrated description of larval morphology and its chaetotaxy for any member of Monotomidae. A description of the pupa of M. angusticollis is also provided; this is the only one to date of a pupa morphological description from this coleopteran family. For the imago, several morphological details are given. According to the head measurements, this species passes through three larval instars (L1-L3). The morphological differences between L1 and L3 relate to the antennal and leg structures, the shape of the labrum and the body surface microsculpture. Diagnostic characters for larvae of Monotomidae and members of Monotoma have been established. The larva of M. angusticollis is distinguished from other known monotomid larvae by its exceptionally asymmetrical mandibles and the short, clavate setae. The morphological and behavioural characters enabling the larvae and imagines of this species to live among ants have also been established, although integration with the host is not as far advanced as in the case of some other myrmecophiles. [ABSTRACT FROM AUTHOR]