Harmochirus brachiatus

Harmochirus brachiatus exhibits the characteristic appearance typical of the genus Harmochirus. The species shows significant sexual dimorphism, with males being particularly distinctive.

Male. Males have a flat eye field that is rhomboidal in shape and broadest at the posterior lateral eyes. The thoracic portion of the carapace is steep and almost vertical. The abdomen is oval and relatively short, approximately as long as the carapace, with the dorsal surface covered by a dark scutum. The most striking feature of males is their enlarged first pair of legs, which have long, broad femora, patellae, and ovoid tibiae that contrast sharply with the thin, elongated metatarsi and tarsi. The width of the tibiae is further enhanced by rows of long, dense black setae. The male palpus has a nearly round bulbus, except for the anterior portion which is flattened transversally. The tibial apophysis is approximately as long as the bulbus, relatively narrow throughout its length, and gently curved upward without basal broadening.

Female. Females are less distinctive than males but can be identified by their epigyne structure. The epigyne has a complex internal structure with complicated copulatory ducts. The sclerotized ducts form broad, flattened loops before connecting to spherical, apparently two-chambered spermathecae. …

H. brachiatus has a wide Asian distribution, having been recorded from India, Bhutan, Bangladesh, China, Taiwan, Korea, Thailand, Vietnam, Malaysia, and Indonesia. The species appears to be particularly common in Southeast Asia, where it has been extensively studied in countries such as the Philippines, Indonesia, and Malaysia.

H. brachiatus plays an important ecological role as a predator in agricultural ecosystems, particularly in rice cultivation systems across Asia. The species has been extensively documented as a beneficial predator that helps control pest insects in rice fields.

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