Arachnologische Mitteilungen 58

30 W. Nentwig, T. Blick, D. Gloor, P. Jäger & C. Kropf Usually, individuals of species occur in different populations and these are connected by gene flow. While a population shows some degree of isolation to the next population, the genetic continuum over all populations of one species guar- antees their species identity (Hartl & Clark 2006). This also means that individuals within one population, and moreover within one species, often show considerable variation within a population and/or across a geographic range. Such variation is the basis for selection and thus one of the drivers of evolu- tion (Hartl & Clark 2006). Additional reasons for differences among individuals or populations may have ecological causes. Colour pattern, body size and shape are characters that show variability and it makes little sense to provide infraspecific taxonomic names for individuals with such minor deviation from the type of the species (e.g. Breitling et al. 2015). Such infraspecific taxa (subspecies, varieties, forms or aberrations), however, have frequently been described in spiders. While the International Code of Zoological Nomenclature (ICZN 2012) accepts subspecies (Article 5.2), in practice they are often taxonomic ballast. Over the last 100 years, the descrip- tion of new subspecies decreased permanently and is currently close to zero (Fig. 1). Obviously, taxonomists today are aware of the genetic, morphological and ecological dynamics in modern species concepts. The World Spider Catalog (2019) currently contains about 48200 valid species, including 1.2 % subspecies. The most active creator of infraspecific names was Embrik Strand with 102 subspecies still valid in 2019, mainly described within two decades (Fig. 1). There are 947 valid species de- scribed by Strand (Tab. 1) (World Spider Catalog 2019) and, by 1926, Strand had also changed nearly 1700 valid spider names because he considered them to be incorrect. Here, we present and discuss the reasons why he did so, the taxonomic validity of his infraspecific names, and the conclusions that may be drawn from this. The arachnologist Embrik Strand Embrik Strand (1876–1947) was a Norwegian arachnolo- gist and studied at the University of Kristiania (now Oslo) where he worked at the university’s museum as a curator from 1901 to 1903. He moved over to Germany in 1903, where he continued studying at the University of Mar- burg. In 1905 he worked for a short time with Staatliches Museum für Naturkunde Stuttgart, the museum in Tübin- gen and the Senckenberg Museum in Frankfurt. In 1907 he moved to Berlin and worked as an assistant at the Museum für Naturkunde of the Humboldt University, followed by his move to the University of Riga in 1923 where he became a professor of zoology. The World Spider Catalog (2019) lists 111 publications by Strand dating from 1899 to 1942, all but two with him as single author and most of them (98) between 1900 and 1917. His extreme productivity was not restricted to arachnology and by 1918, after only 20 years of scientific work, he had already published 1200 articles or books (Wiki- pedia 2019). In the first 20 years of the last century, Strand was con- sidered THE authority in Germany for the identification of spiders from all over the world and he published accordingly. This was also the time when the German museums received large spider collections from the former German colonies in Africa and Asia. Most of them probably passed Strand’s desk and many species were described as new. The infraspecific concept of Strand Strand regarded almost any deviation from the original de- scription as a notable difference sufficient enough to justify/ warrant a separate name. Concepts such as genetic variation, mutation or ecological adaptation were unknown to him. Therefore, each deviation from the nominate species caused him to describe or give a name to the respective specimen(s) as something different, often as a subspecies – regardless of Zusammenfassung. Taxonomische Redundanz bei Spinnen: die infraspezifischen Spinnentaxa von Embrik Strand (Arachnida: Araneae). Strand betrachtete jede Abweichung eines Individuums von der ursprünglichen Beschreibung in Farbe, Körpergröße und -form, Augenanordnung oder Beinbestachelung als ausreichend, um ein eigenes Taxon zu beschreiben. Konsequenterweise etablierte er 165 infraspezifische Taxa wie Unterarten, Varietäten, Formen und Aberrationen, von denen 102 noch heute Gültigkeit haben. Diese Vorgehensweise zeigt eher äußere Ähnlichkeiten als evolutionäre Bezüge auf und soll mit der vorliegenden Arbeit im Licht moderner taxonomischer Prinzipien revidiert werden. Wir erklären 39 Unterarten zu neuen Synonymen der jeweiligen Nominatform, bestätigen 10 zuvor übersehene Synonyme von Unterarten mit der Nominatform, und 26 Taxa sind nomina dubia (einige nach Juvenilen beschrieben oder das Typenmaterial ist zerstört). In 24 Fällen empfehlen wir vertiefte taxonomische Studien der Unterarten bzw. Arten (subspecies und species inquirenda) und 3 Taxa werden zu Arten erhoben (stat. nov.). Fig. 1: Number of spider subspecies described as new taxon per 10 year intervals according to the World Spider Catalog (2019) which are still valid today. Infraspecific taxa described by Strand are given in black, all others in grey 180 160 140 120 100 80 60 40 20 0 Number of spider subspecies described per 10 years 1770 1790 1810 1830 1850 1870 1890 1910 1930 1950 1970 1990 2010