ZOOTAXA ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) Accepted by R. Zahiri: 17 Jul. 2019; published: 19 Aug. 2019 Licensed under a Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0 385 Zootaxa 4657 (2): 385–391 https://www.mapress.com/j/zt/ Copyright © 2019 Magnolia Press Article https://doi.org/10.11646/zootaxa.4657.2.11 http://zoobank.org/urn:lsid:zoobank.org:pub:A0DE0959-A937-49FC-BB08-4747F368840F The Fixator—A simple method for mounting of arthropod specimens and photography of complex structures in liquid DOMINIC WANKE 1,2 , SONIA BIGALK 2 , LARS KROGMANN 1,2 , INGO WENDT 2 & HOSSEIN RAJAEI 2 1 University of Hohenheim, Schloss Hohenheim 1, D-70599 Stuttgart, Germany; 2 Department of Entomology, State Museum of Natural History Stuttgart, Rosenstein 1, D-70191 Stuttgart, Germany e-mail address: dominic.wanke@smns-bw.de Abstract Mounting and preparing arthropods in liquids for photography and further investigations is a challenging task and may lead to unsatisfactory results and, in the worst case, to damage to specimens. A new method is presented here, which allows the fixation of specimens of different sizes under various degrees of pressure. The method is illustrated by three case studies from different groups of insects and arachnids. Keywords: fixation, genitalia dissection, maceration, specimen handling Introduction A major aspect of taxonomy is the description and interpretation of external and internal morphological characters (Dayrat 2005, Mutanen & Pretorius 2007, Padial et al. 2010). Many arthropod dissections are therefore carried out in liquid environments (e.g. ethanol, glycerol) to avoid dehydration and collapsing of structures (Robinson 1976, Ungureanu 1972, Krogmann & Vilhelmsen 2006). During and after dissection, photography of macro- and microstructures in ethanol or glycerol can be chal- lenging, as in most cases photos from specific angles or in natural positions are mandatory for useful comparisons (Wanke & Rajaei 2018). Proper positioning of specimens in liquids can be frustrating, and results may be not sat- isfactory (Su 2016) due to the following disruptive factors, which can lead to artifacts during stacked photography: first the evaporation of ethanol, which can generate a flow causing the specimen or dirt particles around it to drift and secondly, any kind of vibrations (Haselböck et al. 2018). To overcome these problems, different methods have been published so far. Flat objects can easily be fixed by placing them, within the liquid, on a slide covered with a cover glass. However, the pressure of the cover glass can also deform important structures (Wanke & Rajaei 2018). Su (2016) showed that drift and movement of specimens can be minimized by placing them in hand sanitizer gel. Similarly, different concentrations of agarose gel can be used (Haselböck et al. 2018). Wanke & Rajaei (2018) used a fixed tunnel-shaped holder to document important characters in the male genitalia of lepidopterans. However, when specimens or structures need to be photographed from a specific angle, all of the listed methods may be inefficient. Here, we present the Fixator, an easy and low-priced method to fix arthropod specimens of all sizes in almost any position. The method is described and demonstrated through three case studies: (1) documentation of a special structure of the male genitalia of geometrid moths; (2) genitalia dissection of a spider wasp and (3) photography of the tibial apophysis of a spider from different angles. Specimens used for case study Lepidoptera: Geometridae ♂♂: Peribatodes secundaria (Denis & Schiffermüller, 1775), P. umbraria (Hübner, 1809), P. rhomboidaria (Denis & Schiffermüller, 1775)