SHORT COMMUNICATION: ELYTRAL PATTERN OBSERVATIONS AND ECOLOGICAL NOTES OF THE FLOWER CHAFER, Protaetia acuminata (FABRICIUS) (COLEOPTERA: SCARABAEIDAE: CETONIINAE) FROM SINGAPORE

Abstract

Protaetia acuminata (Fabricius, 1775) is one of two species of cetonid beetle of the genus Protaetia found in Singapore. Ecological data concerning this diminutive but charismatic cetonid is scarce. Five separate observations of individual specimens were documented flying into household residences within the Mount Emily Road and River Valley Road area from 2018 to 2021. On 20 March 2021, a healthy population of P. acuminata was discovered living in a covered composter within a private residential property along Saraca Road. Elytral pattern observations of eight specimens (4 males, 4 females) were performed using macro photography. Mean specimen length was 14.1 mm (SD±0.9 mm), and mean width was 7.1 mm (SD±0.5 mm). The highly contrasting colours and seemingly haphazard dots and dashes which make up the elytral pattern of P. acuminata resembled a “QR code”. This is likely a form a disruptive camouflage, breaking up its outline and reducing the risk of detection by predators. Four specimens appeared “light”, i.e., having more light-coloured elytral patches, and four specimens appeared “dark”, i.e., having less light-coloured elytral patches. The degree of light-colouration was not bimodally distributed, with a spectrum of intermediate forms between the lightest and darkest insects. No two specimens were exactly alike; each beetle had a unique elytral pattern compared to the others, demonstrating substantial intraspecific variation within the study population. Furthermore, the pattern of each individual showed fluctuating asymmetry, a type of bilateral asymmetry caused by random deviations. Further studies with larger sample sizes may be necessary to yield greater insights into this fascinating “QR code” beetle.