Fig. 54. Willi Hennig (standing on the ladder) and Hans Sachtleben in the library of the DEI, 1960. Courtesy of the SDEI. chapter four
The taxonomist
4.1. Taxonomy of Extant Animals (Fig. 55)
Hennig used the term ‘taxonomy’ and ‘phylogenetic systematics’ as syn- onyms (1950, no. 76: 35ff.), similarly Mayr et al. (1953: 3), who stated that “in modern usage” the terms ‘taxonomy’ and ‘systematics’ “are used inter- changeably in the fields of plant and animal classifications”. I find a dis- tinction sensible and use ‘taxonomy’ to consider the act of identifying and describing taxa and sorting them into an existing order (Mayr’s ‘alpha- taxonomy’—1969: 24), while ‘systematics’ is the act of investigating on and establishing such an order (as defined in Schmitt & Misof 2009: 315f.). This order is traditionally named ‘natural system’, which is in Hennig’s view necessarily a ‘strictly phylogenetic system’. Willi Hennig’s start into the world of science—as inferred from his pub- lication record—did not evince that he would become one of the world’s leading fly taxonomists. Nevertheless, even his very first scientific paper (Meise & Hennig 1932) on the snake genus Dendrophis contains the roots of what later became Willi Hennig’s original method. The snakes investi- gated belong to the genera Dendrelaphis (at that time called Dendrophis) and Chrysopelea. In both genera are snakes that are able to jump, or better to fling or hurl themselves into the air from tree limbs, thereby stretching their body. The Chrysopelea-species spread out ribs to both sides of the body, thus gliding over a certain distance. The agamids of the genus Draco also produce sort of wings by expanding their ribs. Willi Hennig pounced avidly on the challenge to clarify the difficult taxonomic and nomenclato- rial problems, and the papers produced demonstrate that he succeeded surprisingly well for his age. These papers on reptiles are still useful up today. Already then, Willi Hennig learned to cope with nomenclatural problems, with taxonomic descriptions, and with zoogeographic data. The revision of the genus Draco, 67 pages long, is an example of careful obser- vation and measuring and show that Willi Hennig mastered quite a lot of statistics (in later papers, he rarely returned to statistical analyses). Remarkably, the more general problems which came to Hennig’s mind when he studied the morphological characters and the nomenclatural