Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. X. Infraorder Nepomorpha-Famlies Belostomatidae And Nepidae Author Polhemus, Dan A. Author Polhemus, John T. text Raffles Bulletin of Zoology 2013 2013-02-28 61 1 25 45 journal article 10.5281/zenodo.5351508 2345-7600 5351508 Family NEPIDAE Latrielle, 1802 Discussion . — The family Nepidae has a worldwide distribution, attaining its highest species richness in the tropics of the Southern Hemisphere ( Polhemus & Polhemus, 2008 ). Members of this family, also known as “water scorpions”, have elongate bodies, highly modified raptorial forelegs, and possess an elongate breathing siphon at the posterior tip of the abdomen. Ten species representing three genera occur in Singapore and Peninsular Malaysia . The work of Keffer (2004) provides a very useful and well illustrated analysis of male genitalic characters in this family. For many nepid species the shape of the male parameres is diagnostic, but these structures are not visible externally. Instead, the male operculum at the posteroventral tip of the abdomen must be raised up, and the genitalic capsule gently pulled out in a posterior direction. This is usually best done by inserting a pair of sharp forceps, capturing the genital capsule between their apices, and then carefully working the entire capsule out of the abdomen. Care should be taken not to pull only on the extreme posterior portion of the capsule, since this will often separate from the remainder, in the process damaging other potentially informative internal sclerites, and making the remainder of the capsule harder to remove. As with members of the related family Belostomatidae , live nepids should be handled with care, since all species can inflict a painful bite.