Eur. J. Entomol. 111(2): 275–297, 2014 doi: 10.14411/eje.2014.033 ISSN 1210-5759 (print), 1802-8829 (online) A comparison of the external morphology and functions of labial tip sensilla in semiaquatic bugs (Hemiptera: Heteroptera: Gerromorpha) 1 2 JOLANTA BROŻeK and HERBERT ZeTTeL 1 Department of Zoology, Faculty of Biology and environmental Protection, University of Silesia, Bankowa 9, PL 40-007 Katowice, Poland; e-mail:
[email protected] 2 Natural History Museum, entomological Department, Burgring 7, 1010 Vienna, Austria; e-mail:
[email protected] Key words. Heteroptera, Gerromorpha, labial tip sensilla, pattern, morphology, function, apomorphic characters Abstract. The present study provides new data on the morphology and distribution of the labial tip sensilla of 41 species of 20 gerro- morphan (sub)families (Heteroptera: Gerromorpha) obtained using a scanning electron microscope. There are eleven morphologically distinct types of sensilla on the tip of the labium: four types of basiconic uniporous sensilla, two types of plate sensilla, one type of peg uniporous sensilla, peg-in-pit sensilla, dome-shaped sensilla, placoid multiporous sensilla and elongated placoid multiporous sub- apical sensilla. Based on their external structure, it is likely that these sensilla are thermo-hygrosensitive, chemosensitive and mechano- chemosensitive. There are three different designs of sensilla in the Gerromorpha: the basic design occurs in Mesoveliidae and Hebridae; the intermediate one is typical of Hydrometridae and Hermatobatidae, and the most specialized design in Macroveliidae, Veliidae and Gerridae. No new synapomorphies for Gerromorpha were identified in terms of the labial tip sensilla, multi-peg structures and shape of the labial tip, but eleven new diagnostic characters are recorded for clades currently recognized in this infraorder.