Morphological sexual characteristics of the giant water bug Lethocerus indicus (Lepeletier et Serville, 1825) (Hemiptera: Belostomatidae) in Lao PDR

Abstract

Studies on morphological sexual systematical characteristics of the giant water bug Lethocerus indicus were carried out throughout Lao PDR, conducted in the Centre for Biodiversity Resources Education and Development, Hanoi National University of Education, period 2021-2022. It is not recorded a special sexual difference in morphological characteristics and colour of the giant water bug. The male’s body measurements are smaller than those of the female, 78.64±3.28 and 71.31±4.43 mm, respectively. Differences in sex morphology were observed in their genital structure. The female sex organ is the long, slender, and soft gonapophysis. The male mating organ has a diverticulum, which divides into two parallel paramere branches along the length of the body, forming an inward curved hook at the apex. The proportion between the length and width of the last abdomen segment is the most recognisable feature that contributes to sex discrimination in giant water bug with values of 1.06 and 1.00 respectively in males and females.