Species status of populations of Lethocerus indicus (Lepeletier and Serville, 1825) (Heteroptera: Belostomatidae) in Southeast Asia

Abstract. The giant water bug, Lethocerus indicus (Lepeletier & Serville, 1825), is an aquatic true bug that has been included in the Vietnam Red Data Book since 1992 (“ca-cuong” in Vietnamese, “maeng-da” in Laos and Thailand). This insect also has been listed as an endangered species in Japan, Laos, and South Korea. This study aimed to (1) perform a genetic analysis to determine the species status of various populations of L. indicus in Southeast Asia, and (2) initially survey their distribution in Vietnam and Laos. Four populations were collected: two from the Vientiane Capital and Savannakhet Province areas of Laos, and two from the Vinh Phuc and Long An areas of Vietnam, respectively. Cytochrome oxidase subunit I (COI) fragments longer than 600 bps were amplified by polymerase chain reaction (PCR). Twelve nucleotide polymorphisms were found among these four populations. A maximum likelihood tree based on COI showed that the genetic distances among populations were very small, ranging from 0.2% to 1.1%, and were substantially distant from other populations of Lethocerus. Therefore, they are all considered to be conspecific and to represent L. indicus.