The first water measurers from the Lower Cretaceous amber of Spain (Heteroptera, Hydrometridae, Heterocleptinae)

•Two fossil hydrometrids are studied from Spanish Cretaceous amber.•It is the first definitive record of the family described in amber from Spain.•One new genus and species is erected within Heterocleptinae.•The fossils extend the geological record of this clade by approximately 105 Ma.

Two fossils belonging to a new genus and species of water measurer (Gerromorpha, Hydrometridae), Alavametra popovi Sánchez-García and Nel gen. n., sp. n., are described as first definitive record of the family in Lower Cretaceous (upper Albian) amber from the Utrillas Group (Peñacerrada I site) in Spain. Although several parts of the specimens are obscured due to preservation, a sufficient number of taxonomical characters are visible to consider adequate placement within Heterocleptinae, including the very long posterior pair of cephalic trichobothria inserted on tubercles and the preapical articulation between the first and second antennal segments. The new fossil taxon is included into a cladistic analysis with extinct and extant hydrometrids, and it results putatively basal among the subfamily Heterocleptinae, suggesting that this clade was already present 105 Ma ago.