The cavernicolous fauna of Hawaiian lava tubes, Part VII. Emesinae or thread-legged bugs (Heteroptera: Redvuiidae)

Abstract

This paper describes the world's second troglobitic heteropteran, Nesidiolestes sp., and presents notes on its biology. The species is restricted to the dark zones of high altitude lava tubes on Hawaii Island. Body pigmentation is lacking and the eyes are strongly reduced. This discovery again demonstrates that adaptive radiation of the epigean fauna into cave situations has occurred in Hawaii. Rather than exhibiting relictual characteristics, the species seems recently derived from a surface-dwelling (epigean) ancestor and most closely resembles the extant N. selium Kirkaldy of the same island. Epigean species of Nesidiolestes Kirkaldy have a predisposition for the cave habitat in that they are cryptic, dark-seeking, apparently nocturnal, slow-moving insects frequenting the mossy undersides of fallen logs and ferns in the rain forest. The existence of N. sp. was actually predicted on the basis of the apparently preadaptive habits mentioned. This brings the number of described troglobitic arthropods in Hawaiian lava tubes to eight species.