The oldest aquatic aphelocheirid bug (Heteroptera, Nepomorpha) from the lower Eocene of India

The aquatic bug family Aphelocheiridae currently comprises only the extant genus Aphelocheirus Westwood, 1833, with two subgenera, the nominal one and Micraphelocheirus Hoberlandt & Štys, 1979. The genus is widely distributed in Europe, Asia, Africa, but seems to be absent from the New World (Schuh & Weirauch, 2020). These small predatory insects live at the bottom of lakes and ponds, and breath thanks to highly specialized abdominal respiratory ‘rosettes’ characteristic of this family (Thorpe & Crisp, 1947a, b; Schuh & Slater, 1995). The closely related Naucoridae have to breathe at the surface of the water. Ye et al., 2020: fig. 4) proposed a late Triassic age for the Naucoroidea and separation between the Naucoridae and the Aphelocheiridae, but Wang et al. (2021: fig. 4) proposed that the (Potamocoridae + Aphelocheiridae) separated from the Naucoridae during the Jurassic and that the Aphelocheiridae could be early Cretaceous. The accurate aphelocheirid fossil record is very scarce, with the oldest known representative from the Eocene (Bartonian) of Germany (Moraweck et al., 2015); and a second fossil from the Pliocene of Germany (Popov, 2007; Kunzmann et al., 2017).