96 WATT 
In the course of this study, type series of all known nominal species of 
Mimopeus have been examined and lectotypes selected and labelled. The type 
series of Mimopeus elongatus Bréme was located in the Zoological Museum of the 
University of Turin (with the assistance of Professor Pietro Passerin d’ Entréves) in 
a box separate from the main Breme collection which is housed in cabinets. 
Lectotypes of the remaining species were examined and labelled in the British 
Museum (Natural History). 
Because of the considerable length of this paper which covers additional 
research on previously described species as well as descriptions of new species of 
Mimopeus, it has been decided to publish the paper in two parts. The first part 
consists of a description of taxonomic methods and techniques, a description of the 
genus Mimopeus, a key to species of Mimopeus and a full description of nine new 
species. The second part, which it is planned to publish in the next issue of the 
Records, includes additional information on previously described species and a 
critical review of previously published data. There are thirty species involved, of 
which sixteen are synonyms. Finally, there is a discussion on the biogeography and 
ecology of the genus. 
TAXONOMIC METHODS 
Specific taxonomic characters 
Virtually any observable heritable attribute may provide a useful taxonomic 
character, if its expression differs from one taxon to another. In this revision the 
external morphology of the exoskeleton and of the external male genitalia of the 
adult beetles have been used to define the species, together with what data has 
been available concerning their distribution and ecology. Certain internal 
characters and the structure of the ovipositor are used in addition in describing the 
genus. No visible external character has been neglected, but some have been found 
to be of no use in taxonomic discrimination at the specific level because of their 
constancy throughout the genus, while others are of little use in discrimination 
because of considerable individual and geographical variation. The characters 
which have proved most useful will be found in the keys and diagnoses, while the 
others are mentioned in the descriptions. In Mimopeus there is not a single specific 
discriminatory character examined which is not subject to geographical variation. 
This applies as much to the form of the aedeagus (cf. M. elongatus) as to most other 
characters. The aedeagus, however, shows very little individual variation. 
Linear dimensions and ratios 
These are useful in specific discrimination in some insects. In such cases the 
adults vary little in size or proportions. It was decided at the beginning of the study 
of Mimopeus to make series of measurements in order to ascertain whether any 
dimensions or ratios were sufficiently constant within, and sufficiently different 
between species, to distinguish closely related species and to study and describe 
individual and geographical variation. 
