Orthetrum glaucum vs Orthetrum luzonicum

It is quite a challenge for laymen to tell apart Orthetrum glaucum from Orthetrum luzonicum because both (matured males) are light blue in colour. Actually, we are still able to distinguish them if we look at them carefully. Orthetrum glaucum is slightly larger than Orthetrum luzonicum. The hindwing base of Orthetrum glaucum has dark patch, but this is absent in Orthetrum luzonicum. Apart from that, the abdomen of Orthetrum luzonicum is slightly slender if compared to Orthetrum glaucum.

Orthetrum luzonicum (male; left) and Orthetrum glaucum (male; right)

UKM Bangi, Selangor