An updated checklist of type material of dragonflies and damselflies (Odonata) housed in the Zoological Museum Hamburg (ZMH), Germany

We present an updated checklist of type specimens of dragonflies (Odonata: Anisoptera) and damselflies (Odonata: Zygoptera) housed in the collection of the Zoological Museum of Hamburg (ZMH), part of the Centrum für Naturkunde (CeNak), Hamburg, Germany. We list all types currently housed in the dry and wet collections of the museum and compare the current holdings to the previous catalogues provided by Weidner (1962, 1977). In total, the collection of the ZMH currently houses 84 type specimens belonging to 44 species (38 of which are still valid species); these include 17 holotypes, 7 syntypes, 4 lectotypes, 33 paratypes, and 23 paralectotypes. We here provide an updated list of Odonata types in the ZMH, which includes any changes in taxonomy, but also corrects mistakes of previous catalogues.


Introduction
Type collections represent the most valuable material in museum collections as they are the ultimate reference for species (Bradley et al. 2014;Schindel and Cook 2018). However, the locations of many types remain unknown as museums often do not have the capacity to provide complete lists of their types, or even images of all specimens, despite enhanced efforts of digitization. Therefore, complete type catalogs are a valuable resource for the community.
The Centrum für Naturkunde (CeNak) was newly founded in 2014 and is the umbrella for the mineralogical, the geological-paleontological, and the zoological collections. The zoological collection, also known as the Zoological Museum of Hamburg (ZMH), has a long tradition and was originally established in 1843. Important collections, such as the ones from the Museum Goddefroy (1861-1885), a private museum based on collections as-sembled by Johann Cesar VI Godeffroy, were bought and implemented in the the ZMH. However, large parts of the collections, especially the dry material of the collection of holometabolous insects was destroyed during the second World War (WW2) in 1943. Fortunately, most of the collection of hemimetabolous insects could be saved; hence, this part of the Hamburg collection is specifically old, valuable and rich in type specimens.
Herbert Weidner was the curator of the entomological collections in Hamburg after WW2 (between 1950 and1976) and rebuild much of the collections following their partial destruction. He was also the first to provide commented catalogues on the collections with a focus on the types housed in Hamburg; he published these catalogues of the entomological and arachnological collections in a series of papers between 1962 until 1977 in the journal Mitteilungen aus dem Hamburgischen Zoologischen Museum und Institut. Most of these contributions were pub- lished in German, restricting their accessibility for international scientists. Since Weidner, no further catalogues were published on the collections until recently, when catalogues on the solifigues (Harms and Dupere 2018), on the mayflies (Satori et al. 2016) and on the Caelifera and Ensifera have been published (Dey and Husemann 2018a, b). In this paper we provide an updated checklist of the types of dragonflies and damselflies currently housed in the collection of the ZMH based on the original catalogues of Odonata by Weider (1962Weider ( , 1977. We further provide images of example labels of the most important taxonomists having worked with the collection.

Results and discussion
In his first catalogue in 1962, Weidner listed the types of 41 species of dragon-and damselflies; in his update from 1977 he reported the types of seven additional species, raising the total number of species of which types should be held in the collection to 48. The types of five of these 48 species were considerd lost by Weidner (1962Weidner ( , 1977: Neurothemis nesaea Ris, 1911, Leptogomphus retroflexus Ris, 1921, Anax chrysomelas Ris, 1911, Nesobasis longistyla Selys, 1891and N. nigrostigma Selys, 1891. Hence, the types of 43 species and subspecies were present in 1977. Currently, the collection of the ZMH houses the types of 44 species (38 of which are still valid). In total 84 type specimens are present in the collection; these include 17 holotypes, 7 syntypes, 4 lectotypes, 33 paratypes and 23 paralectotype ( Table 1). Most of the species currently held in the collection were already documented in Weidner's catalogues. The types of Neurothemis nesaea Ris, 1911 andLeptogomphus retroflexus Ris, 1921 (now Heliogomphus retroflexus), which were listed as missing by Weidner (1962) were re-discovered. A specimen labelled as syntype of Trithemis dichroa (Karsch, 1893) is present in the collection (ZMH65941), but was suggested to be invalid by Weidner (1962). Based on the collection data, we agree with Weidner (1962), that this is not a syntype of the species as the type location, as well as the collection date of the original descriptions do not match. The type     Weidner (1962). Table 1. List of type specimens currently housed in the collection of the ZMH. Collection numbers, current valid name and senior synonymies, type status, as well as important collection information are given. Current taxonomic assignment is based on Bridges (1994), Steinmann (1997aSteinmann ( , 1997b and Schorr and Paulson (2019); all specimens besides ZMH65834 are kept dry. † after the type = is lost. Lectotype assigned by K. F. Buchholz (1959) 4 Lectotype assigned by K. F. Buchholz (1959) *stated as missing of Anax chrysomelas Ris, 1911listed in Weidner (1962 and Nesobasis longistyla Selys, 1891and N. nigrostigma Selys, 1891in Weidner (1977 as missing could not be found; however, Bridges (1994) lists the types of the Nesobasis species for the Institut Royal des Sciences Naturelles de Belgique (IRSN); hence, they may not be lost but in a different location. Weidner (1962) listed the type of Anax chrysomelas Ris, 1911 as lost. However, this species cannot be found in any other catalogue than that of Weidner (1962) and hence its species status is doubtful. Further, the types of Tramea samoensis Brauer, 1867, and T. transmarina Brauer, 1867, which were reported by Weidner (1962) were not found and hence have to be considered lost.

ID
The types held in the ZMH collection have specific value, as many originate from tropical regions, which are difficult to access or where habitats of the species no longer exist. The majority of species the ZMH holds types of were described by Martius A. Lieftinck, Friedrich Ris, Emond de Selys, and Friedrich M. Brauer, important taxonomists of Odonata (see Fig. 1 for typical labels). Many of the species described by the above mentioned authors were based on material from the collections of the private Museum Goddefroy. Karl F. Buchholz investigated additional material from this collection housed in the ZMH and re-discovered and re-described some type material (Buchholz 1959). It remains possible that additional types are housed in the collection, which are not labelled as such. Detailed digitization and the work of specialists in the collection in the future will help to unlock its potential.