Patterns of Distribution and Diversity in European Mygalomorph Spiders

Patterns of distribution and diversity in European mygalomorph spiders Autor(en): Decae, Arthur E. Objekttyp: Article Zeitschrift: Contributions to Natural History : Scientific Papers from the Natural History Museum Bern Band (Jahr): - (2008) PDF erstellt am: 24.09.2021 Persistenter Link: http://doi.org/10.5169/seals-787057 Nutzungsbedingungen Die ETH-Bibliothek ist Anbieterin der digitalisierten Zeitschriften. Sie besitzt keine Urheberrechte an den Inhalten der Zeitschriften. Die Rechte liegen in der Regel bei den Herausgebern. Die auf der Plattform e-periodica veröffentlichten Dokumente stehen für nicht-kommerzielle Zwecke in Lehre und Forschung sowie für die private Nutzung frei zur Verfügung. Einzelne Dateien oder Ausdrucke aus diesem Angebot können zusammen mit diesen Nutzungsbedingungen und den korrekten Herkunftsbezeichnungen weitergegeben werden. Das Veröffentlichen von Bildern in Print- und Online-Publikationen ist nur mit vorheriger Genehmigung der Rechteinhaber erlaubt. Die systematische Speicherung von Teilen des elektronischen Angebots auf anderen Servern bedarf ebenfalls des schriftlichen Einverständnisses der Rechteinhaber. Haftungsausschluss Alle Angaben erfolgen ohne Gewähr für Vollständigkeit oder Richtigkeit. Es wird keine Haftung übernommen für Schäden durch die Verwendung von Informationen aus diesem Online-Angebot oder durch das Fehlen von Informationen. Dies gilt auch für Inhalte Dritter, die über dieses Angebot zugänglich sind. Ein Dienst der ETH-Bibliothek ETH Zürich, Rämistrasse 101, 8092 Zürich, Schweiz, www.library.ethz.ch http://www.e-periodica.ch European Arachnology 2008 (W. Nentwig, M. Entling & C. Kropf eds.), pp. 41-50. © Natural History Museum, Bern, 2010. ISSN 1660-9972 (Proceedings of the 24th European Congress ofArachnology, Bern, 25-29 August 2008). Patterns of distribution and diversity in European mygalomorph spiders ARTHUR E. DECAE Terrestrial Ecology Unit, Department ofBiology, University of Ghent, Ledeganckstraat 35, B-9000 Gent, Belgium. Natuurhistorisch Museum Rotterdam, Posthus 23452, 3001 KL Rotterdam, The Netherlands. Abstract A coherent picture of the distribution and diversity of the European mygalomorph spider fauna is presented for the first time. The picture is based on geographical and taxonom- ical information, mainly obtained in recent collection work. The patterns reveal that (1) the current distribution of the Atypidae is the result of a Holocene dispersal event; that (2) Nemesiidae and Cyrtaucheniidae are building-up their diversity in situ as an effect of repeated fragmentation and isolation of local populations during successive Pleistocene glaciations; that (3) Ctenizidae, with three locally restricted and geographically isolated genera, are most probably remnants of a former geography of the Mediterranean region; that (4) the Theraphosidae seem to show both evidence of dispersal in Chaetopelma and of speciation in situ in Ischnocolus; that (5) the Hexathelidae are either very old remnants or recent man aided introductions into the European mygalomorph fauna. INTRODUCTION sity assessments and conservation studies. Thanks to collection efforts of mainly young The here presented view on the European arachnologists from southern Europe, a mygalomorph fauna was developed from the coherent picture of the European mygalomorph results of these studies. To make the emerging fauna is now emerging. The European patterns visible, all available information mygalomorph spider fauna as discussed on geographical locations from which here includes species occurring in the identifiable mygalomorph spiders have been northernmost parts of Africa (Fig. 1). Until recently, reported, are mapped (Fig. 1). The resulting almost all the knowledge of European patterns of diversity and distribution reflect mygalomorphs was based on isolated taxo- important aspects of the evolutionary nomic work mainly conducted in the late history of the different mygalomorph families, 19th and early 20th centuries. The problem and contain basic information for developing was that nearly all this work was done as prospective research programs studying idiosyncratic descriptions of small haphazardly the ecology, behaviour and evolution of these collected samples, from which it was primitive spiders. very difficult to develop an overall view of the European mygalomorph fauna. Recently a number of larger and more systematically conducted collection programs have been carried out, mainly in relation to biodiver¬ 42 European Arachnology 2008 Fig. 2. Extent of permafrost at the end of the last ice age (hatched) and permafrost front (dashed line). After Hewitt (1999). Decae: Patterns ofdistribution and diversity in European mygalomorph spiders 43 Family Asia Europe Africa N. America S. America Australia Actinopodidae + + Antrodiaetidae + + Atypidae + + + + Barychelidae + + + + Ctenizidae + + + + + + Cyrtaucheniidae + + + + + + Dipluridae + + + + + Hexathelidae + + + + + Idiopidae + + + + Mecicobothriidae + + Microstigmatidae + + Migidae + + + Nemesiidae + + + + + + Paratropidae + Theraphosidae + + + + + + 10 6 11 8 13 10 Table 1. Occurrence of different mygalomorph spider families per continent showing the comparative poverty of the European mygalomorph fauna. MATERIAL AND METHODS review and general discussion see Hewitt, Data on the distribution and diversity of 1999). European mygalomorph spiders were collected in an extensive survey of the extant RESULTS literature, museum collections and large With only six of the presently recognized private and institutional collections from fifteen families (Table 1), the European regions all over the area of interest. More mygalomorph fauna is relatively poor. The than five hundred specimens, including mygalomorph distribution, when viewed at the representatives of all Western Palearctic genera, family level appears as a pattern of curved were morphologically studied with the aid lines running in an east-west direction that of a Ceti-Medo 2 binocular microscope in are separated with respect to their northern order to assess the European mygalomorph latitudes (Fig. 3). From this perspective diversity and to produce a determination mygalomorph families seem to have repopu- key for European mygalomorph species now lated Europe from the south over a broad in preparation. These data were amassed in front after the melting of the last permafrost a Microsoft Access Data Base and analyzed of the younger Dryas some 11.500 years ago. for distribution and diversity with the aid of Focusing on the genus and species levels, DIVA-GIS geographical computer program however, the situation is more complex and (Hijmans et al. 2005). The resulting distribution more informative. maps were reviewed in reference to current knowledge of the Pleistocene history of Atypidae (Fig. 4) Europe (Fig. 2) and the repopulation of the The Atypidae, probably thanks to their central and northern parts of the continent capacity to balloon, have the broadest extent in after the last glaciation (for a comprehensive Europe being distributed all over the con- 44 European Arachnology 2008 Fig. 3. Broadly east-west running curved dashed lines indicate the northern limits of the distribu tions of the six mygalomorph spider families occurring in Europe. Atypus S affinis A muraiis <& piceus Fig. 4. Distribution of the genus Atypus in Europe (as based on the currently included data points). Dashed line indicates latest permafrost front (see Fig 2). Block arrows indicate supposed Holocene dispersal routes of three Atypus species into formerly frozen territory. Decae: Patterns ofdistribution and diversity in European mygalomorph spiders 4 5 tinent with exception of the most northern peated close coexistence of cork- and wafer- parts. Their distribution reaches far into the door strategies in many Nemesia populations latest permafrost coverage of the continent (Moggridge 1873, Decae 1996). and can therefore best be explained as the result of a relatively recent Holocene dispersal Cyrtaucheniidae (Fig. 6) event. This hypothesis gains further support Although more restricted to the south-west, from the low diversity observed within the European Cyrtaucheniidae appear to the Atypidae with just one genus, Atypus have a somewhat similar evolutionary Latreille, 1804, and three species broadly history as the Nemesiidae. Here also we see distributed in eastern, central and western restricted species ranges and high species ranges. It has been suggested that the Atypus diversity (Platnick 2008). However, too little species have survived the last ice-age in is currently known about cyrtaucheniid three isolated southern refuge populations taxonomy, occurrence and behaviour to draw in the Iberian Peninsula, the Southern further conclusions about survival capacity, Balkans and a region near the Caspian Sea ecological or behavioral versatility or to suggest respectively (e.g. Schwendinger 1990). prospective research programs for this group. Nemesiidae (Fig. 5) The Nemesiidae do not occur north of the Ctenizidae (Fig. 7) Alpine mountain ranges. Apparently they The focus of diversity in the European did not colonize the former permafrost Ctenizidae is on the genus, rather than on the species regions of central and northern Europe as Atypus level. This might indicate an older did. Also in contrast to the Atypidae the evolutionary history, not so much influenced by European Nemesiidae are very diverse with Pleistocene glaciations, as by tectonic events three genera and over sixty species known that shaped the present day geography of

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