Two unusual new genera of cavernicolous Hydrometridae (Insecta: Heteroptera) from eastern Brazil

Abstract

Two new genera of cavernicolous Hydrometridae are described from limestone caves in northeastern Brazil: Spelaeometra n. gen., with type species S. gruta n. sp., from the Lapa D’Água do Zezé, Lapa do Nestor, Lapa do Saco Velho, and Lapa do Caboclo caves in Minas Gerais state; and Cephalometra n. gen., with type species C. pallida n. sp., from the Natividade cave in Tocantins state. Both new taxa are flightless, possess reduced eyes, and exhibit other reductional character states linked to life in underground ecosystems. The new taxa are interpreted to be highly aberrant members of the family Hydrometridae, based on the possession of eyes set well forward on the head capsule, the posterior pair of cephalic trichobothria arising from distinct tubercles, the presence of an apical invagination on the fourth antennal segment, and the structure of the male parameres. They are provisionally placed in the subfamily Hydrometrinae based on the apical articulation between the first and second antennal segments. On the basis of a preponderance of shared apomorphic character states these new genera appear most closely allied to Veliometra schuhi Andersen, which is also endemic to Brazil, although currently placed in a different subfamily. Color habitus photographs and line drawings of key characters are provided for both new taxa, accompanied by maps and photographs of the caves in which the species occur.