A review of the New Zealand Berosus (Coleoptera: Hydrophilidae) with descriptions of three new species Author Seidel, Matthias Centrum für Naturkunde, Universität Hamburg, Martin-Luther-King Platz Author Sýkora, Vít Department of Zoology, Faculty of Science, Charles University, Viničná Author Leschen, Richard A. B. Hamburg, Germany; e-mail: matthias. seidel @ uni-hamburg. de Author Fikáček, Martin Department of Zoology, Faculty of Science, Charles University, Viničná & Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan; e-mail: mfikacek @ gmail. com & Department of Entomology, National Museum, Cirkusová 1740, Prague text Acta Entomologica Musei Nationalis Pragae 2021 Acta. Ent. Mus. Natl. Pragae 2021-07-03 61 1 243 252 http://dx.doi.org/10.37520/aemnp.2021.014 journal article 10.37520/aemnp.2021.014 1804-6487 5354355 09B6B962-1AA4-4A7B-94DC-503E5A964F2B Key to adults of the New Zealand species of Berosus See also Table 1 for the summary of diagnostic characters and their comparison among species. 1 Pronotum with large rectangular dark spot covering nearly whole surface, basal half of femora black, elytral apices simple and closing tightly, small species ( 3.5–4.8 mm ). ................................................................ 2 – Pronotum with large rectangular dark spot narrowing anteriorly, basal half of femora yellow, elytral apices expanded and leaving a gap, large species (4.4–6.0 mm). ................................................................................ 3 2 Aedeagus small, with straight parameres in lateral view, median lobe wide and nearly reaching parameral apices. Female with apical abdominal emargination rectangular. ............ B. pallidipennis ( Sharp, 1884 ) – Aedeagus medium-sized, with slightly bent parameres in lateral view, median lobe narrow and much shorter than parameres. Female with apical abdominal emargination semicircular. ....................... B. maru sp. nov. 3 Aedeagus medium-sized, with strongly bent parameres in lateral view, median lobe narrow and much shorter than parameres. Female with apical abdominal emargination semicircular. ....... B. halasi sp. nov. – Aedeagus large, with straight parameres in lateral view, median lobe narrow and much shorter than parameres. Female with apical abdominal emargination rectangular. ............................ B. muellerorum sp. nov.