A morphometric analysis was conducted on Rhynchophorus vulneratus and R. ferruginous (Coleoptera: Curculionidae) insular and mainland populations. Twenty-three morphological characters were measured and the data were analysed using independent t-test, principal component analysis (PCA) and discrimination function analysis (DFA). Using independent t-test, all characters were found to be significant at p < 0.05, except distance between eyes (ED), mesotarsus length (F2Ta) and metatarsus length (F3Ta). In PCA, cumulative variations of 80.7% were recorded from the first two principal components, resulting from high loadings in elytra length (EL), elytra width (EW) and pronotum length (PL). For DFA, a single function explained a canonical correlation of 0.952 with 100.0% of variation and the Wilk’s Lambda statistics (0.094) was strongly supported with p < 0.0001. The highest character loadings were the total length (TL), elytra width (EW) and pronotum length (PL), which were useful as diagnostic characters for separating both Rhynchophorus species. Therefore, this study suggests that R. vulneratus and R. ferruginous are morphologically distinct species. This finding proves that the insular population of R. vulneratus fits the generality of the ‘island rule’ as being larger compared to the mainland counterparts of R. ferruginous. Keywords: Morphometrics, mainland, insular population, Rhynchophorus, weevils

The phylogeny of 43 species under 20 genera of seven subfamilies of weevils’ species (Coleoptera: Curculionidae) from Malaysia were successfully inferred based on 34 morphological characters, of which combined the qualitative and quantitative inputs. The monophyletic clade of the Curculionidae was supported by Neighbor Joining (NJ) and Maximum Parsimony (MP) trees with bootstraps values of 79% and 76%, respectively. Although the arrangement and placement among the 19 species of Dryophthorinae were not fully resolved, however the phylogenies were able to elucidate the relationships of the other curculionids from the Curculioninae, Entiminae, Lixinae and Molytinae subfamilies. Therefore, further multivariate analyses were conducted on 17 selected species of Curculionidae, which has been successful to discriminate the examined species. From the principal component analysis (PCA; eigenvalues of PC1 for cluster 1 = 7.4650; eigenvalues of PC1 for cluster 2 = 5.1874) and canonical variate analysis (CVA; cluster 1 with p < 0.0001; cluster 2 with p < 0.0001), the diagnostic morphological characters were resulted from the elytron, pronotum, total length of body, and femur length. As a conclusion, the morphometrics has proven to be reliable and informative as another alternative to subfamilies classification and to show the relationships within the examined insect’s species. However, it is also recommended that further studies should include more diagnostic and informative characters to represent up to the tribes or genus levels in future.

Morphological variation of the red stripe weevils, Rhynchophorus vulneratus (Coleoptera: Curculionidae) was investigated using three different populations from Kota Samarahan (Sarawak), Mukah (Sarawak), and central of Peninsular Malaysia. A total of 145 individuals were morphologically examined in which 23 morphological characters of head, body and legs were linearly measured. All data were analysed using Principal Component Analysis in Minitab Version 17.1. The first three principal components explained 82.5% of variance with eigenvalues greater than 1.0 and the principal component plot of PC1 against PC2 showed the clustering of the three populations, in which Mukah population forms its own cluster whereas Kota Samarahan and Peninsular Malaysia populations show overlapping clusters. The morphometric findings indicated that the pronotum and elytra were the most diagnostic characters for discriminating the three examined populations. This suggests that the populations of R. vulneratus might have undergone adaptive changes on its morphological characters possibly due to different environmental factors including the availability of food resources, habitat types,and human activities and this requires further testing.