MIMOPEUS 97 
Measurements were made initially with a linear graticule fitted to a 
stereoscopic binocular microscope calibrated against a graduated slide. 
(a) Dimensions measured and abbreviations. The following abbreviations and 
definitions of dimensions apply throughout this paper, in addition to overall length 
and width. 
Pr.L. — middle length of pronotum. 
EL.L — middle length of elytra. 
Pr.W — greatest width of pronotum. 
Ap.W.— width of apex of pronotum (between points of anterior angles). 
H.W. — Head width anterior to eyes (between outer margins of canthi). 
“Total length” is an unreliable measurement as the head is frequently bent 
downwards or partly retracted into the prothorax in mounted specimens. Width 
and pronotal width are not ideal measurements as the relative positions of greatest 
width may vary from species to species or even between infraspecific populations. 
(b) Abbreviations for statistics. The following abbreviations apply to statistics 
calculated from measurements. 
Mean — arithmetic mean. 
S.D. — standard deviation. 
C.V. — coefficient of variability (S.D. expressed as a percentage of the mean). 
N — number of specimens measured. 
(c) Comparision of statistics of populations of Mimopeus. Table 1 compares 
statistics calculated from linear measurements of samples of six populations of 
Mimopeus. These populations belong to four species of two species groups 
(elongatus group : elongatus and turbotti; opaculus group : opaculus and insularis). 
Each sample was selected from a series collected at a single locality, thus 
representing (presumably) members of a single deme. Sampling was random. 
Most of the means differ significantly. The opaculus group populations are 
readily distinguished from the elongatus group populations by their larger size, the 
only overlap of ranges occurring in Pr.W. between M. turbotti and M. opaculus. It 
is apparent also that the tabulated dimensions are useless for distinguishing M. 
elongatus from M. turbotti. The Red Rocks population of M. opaculus is 
distinguishable from M. insularis by the larger elytra of the latter, but if other 
populations of opaculus are considered, the ranges overlap. M. opaculus is very 
variable in size depending on its geographical origin: length 13,1-22.8 mm, width 
6.8-12.9 mm). 
On the basis of the information obtained from the six populations listed in 
Table 1 it was decided that the dimensions are not sufficiently useful in separating 
species to justify the enormous amount of time that would have been required to 
measure every specimen. With a finely graduated millimetre scale it is possible to 
measure beetles with an error of + 0.2 mm or less (which is quite adequate for 
those as large and variable as Mimopeus). Most of the dimensions quoted in the 
specific descriptions were made thus, and are confined to length and width only. 
Used in addition to other characters these dimensions will assist identification of 
some species. 
In Table 2 the dimensions of males and females of five populations have been 
separated and statistics calculated for each sex. The Te Hope population belongs to 
M. elongatus (cf. Table 1 for identity of other populations). The dimensions of 
specimens of four of these populations have been plotted as histograms in Fig. 1. 
