A gynandromorph of the horned beetle, Trypoxylus dichotomus septentrionalis (Kôno, 1931) (Coleoptera, Scarabaeidae) was morphologically observed using a microfocus X-ray computed tomography system (micro-CT) and a scanning electron microscope (SEM). In the head, the horn is lacking, and it bears three small protuberances as normal female. The left mandible has the following female characteristics: large, trapezoid dorsal process and thick setae on the dorsal side. In contrast, the right mandible has the following male characteristics: small, triangular dorsal process and sparse setae on the same side. After an examination of the prothorax of the gynandromorph using micro-CT, the muscles for moving the head dorso-ventrally were almost same as those of normal male in size. The other some parts of the gynandromorph bear the male characteristics, namely the pronotum with a bifurcate horn, a smooth and very sparsely pubescent dorsal surface on the pronotum and the elytra, large muscles for moving the head dorso-ventrally inside the pronotum, and male genitalia.

After more than 120 years since the description of Colletes seitzi Alfken, 1900, it was confirmed that it inhabits the Kantô region (Kanagawa and Chiba Prefectures) so far in Japan. Currently the distribution of two species, C. seitzi and C. esakii belonging to the caspicus species group in Japan was revealed.

Studies of insect assemblages are increasingly needed to elucidate the pattern of insect diversity and the factors that affect them because many insects are declining due to environmental and land use change, and contribute to various ecosystem functions and services, such as herbivory, decomposition, pollination of fruits and crops, and pest control. In this paper, I explain (1) appropriate research design, (2) evaluation of sample effort and estimation of species number, diversity, and coverage, and (3) indicator species analysis, which are very useful for the studies of insect assemblages but have not been well described in Japanese so far. I illustrated analytical examples using our data on surveys of butterfly assemblages in clear-cuts and grasslands which were already published elsewhere. I also provided R code for these analyses. Some advantages and limitations of these analytical methods were discussed. All the data and R script used here are available from the electronic repository.