Ghosts of subterranean waters: two new troglobitic species of Spelaeometra D. Polhemus & Ferreira, 2018 (Heteroptera: Hydrometridae) from Brazil, with remarks on the enigmatic species Cephalometra pallida D. Polhemus & Ferreira, 2018

Spelaeometra D. Polhemus & Ferreira, 2018 is a rare genus within the family Hydrometridae, currently composed exclusively of cave-dwelling species. Herein, we describe two new troglobitic species of this enigmatic genus from southwestern Bahia, Brazil: Spelaeometra ybykoara sp. nov. from the municipality of Carinhanha, and Spelaeometra iuiu sp. nov. from the municipality of Iuiú. The new species are primarily distinguished by diagnostic differences in the morphology of the male genitalia and, despite extensive sampling in surrounding caves, are currently known only from their respective type localities. Moreover the taxonomic descriptions, we provide new information on ecology, habitat characteristics, and potential threats affecting both species. Additionally, we present new remarks on Spelaeometra gruta Polhemus & Ferreira, 2018, and on the elusive, rarely collected species Cephalometra pallida D. Polhemus & Ferreira, 2018, providing new information on their natural history.