Arachnologische Mitteilungen 56

Dimorphic males in Troxochrus scabriculus 53 Conclusion It is evident that the synonymy of T . scabriculus / cirrifrons is not a taxonomically problematic case to resolve. Since both males and females from populations with co-occurring male forms are identical in their genital morphology, it is highly plausible that the different male morphs must represent two forms of the same species. It is also apparent that Troxochrus scabriculus (Westring 1851) is the typical form, while the later described form cirrifrons is a second male morph that must be designated Troxochrus scabriculus forma cirrifrons (O. Pickard- Cambridge, 1871). Based on further evidence from distribu- tion maps, habitat preferences, phenology and appearance in populations (see above), it is obvious that Simon (1884) made the correct judgement from the very start. Although breeding experiments would be desirable to cla- rify the status of the two forms of the male spider, as once recommended, we consider the taxonomic case of the dimor- phic males in T. scabriculus to be closed and quote the famous fictional figure Sherlock Holmes: “We must fall back upon the old axiom that when all other contingencies fail, whate- ver remains, however improbable, must be the truth” (Doyle 1908). Acknowledgements We wish to thank Dr Dr John Plant for checking the English and for his constructive comments on the manuscript. We are especially grateful to Pierre Oger for allowing us to use his photographs of the male palps from his website (see Oger 2018 in the References). References Aakra K, Morka GH, Antonsen A, Farlund M, Wrånes RE, Frø- landshagen R, Løvbrekke H, Furuseth P, Fjellberg A, Lemke M, Pfliegler WP, Andersen S, Olsen KM, Aadland B & Berggren K 2016 Spiders new to Norway (Arachnida, Araneae) with ecolo- gical, taxonomical and faunistic comments. – Norwegian Journal of Entomology 63: 6-43 Blagoev G, Deltshev C, Lazarov S & Naumova, M 2018The spiders (Araneae) of Bulgaria. Version: August 2018. National Museum of Natural History, Bulgarian Academy of Sciences. – Internet: http://www.nmnhs.com/spiders-bulgaria (25.11.2018) Bosmans R 2009 Een herziene soortenlijst van de Belgische spinnen (Araneae). – Nieuwsbrief van de Belgische Arachnologische Vereniging 24: 33-58 Bosmans R&Oger P 2018On two cases of male dimorphism in dwarf spiders (Araneae: Linyphiidae). – Arachnologische Mitteilungen 55: 52-56 – doi: 10.30963/aramit5509 Bosmans R & Van Keer K 2017 Een herziene soortenlijst van de Belgische spinnen (Araneae). – Nieuwsbrief van de Belgische arachnologische Vereniging 32: 39-69 BristoweWS 1939The comity of spiders 1. – Ray Society 126: 1-288 Broen B von&MoritzM1965 Spinnen (Araneae) undWeberknechte (Opiliones) aus Barberfallen von einer tertiären Rohbodenkippe im Braunkohlenrevier Böhlen. – Abhandlungen und Berichte des Naturkundemuseums Görlitz 40(6): 1-15 Broen B von 1977 Zur Kenntnis der Spinnenfauna des Berliner Raums. I. Spinnen eines xerothermen Kulturbiotops (Araneae). – Deutsche Entomologische Zeitschrift N.F. 24: 411-417 – doi: 10.1002/mmnd.19770240415 Dekkers-Scheutjens A 2010 Spinnen (Araneae) van het Natuurreser- vaat “De Kaaistoep” [The spiders (Araneae) of the nature reserve “De Kaaistoep”]. – Nieuwsbrief SPINED 28: 8-21 Deltshev C 2004 Spiders (Araneae) from Sandanski-Petrich Valley (SW Bulgaria). –Mitteilungen aus dem Museum für Natur- kunde in Berlin, Zoologische Reihe 80: 71-76 – doi: 10.1002/ mmnz.20040800106 Doyle AC 1908The Adventure of the Bruce-Partington Plans. –The Strand Magazine (December 1908) (no pagination) Entling W, Schmidt MH, Bacher S, Brandl R & Nentwig W 2007 Niche properties of Central European spiders: shading, moisture and the evolution of the habitat niche. – Global Ecology and Biogeography 16: 440-448 – doi: 10.1111/j.1466- 8238.2006.00305.x Esser T 1997 Artenvielfalt in der modernen Agrarlandschaft: Der Feldrain rekultivierter Anbauflächen als Lebensraum für Spinnen (Arachnida, Araneae) und Asseln (Isopoda, Oniscoiidea). – Acta Biologica Benrodis, Supplement 6: 1-131 Harvey PR, Nellist DA &Teller MG (eds) 2002 Provisional atlas of British spiders (Arachnida,Araneae),Volume 1.Biological Records Centre, Huntingdon. 214 pp. Heimer S 1976 Interessante Spinnen aus der Umgebung von Alten- burg (Araneae. Linyphiidae et Micryphantidae). – Faunistische Abhandlungen aus dem Museum für Tierkunde in Dresden 6: 125-128 Helsdingen PJ van & IJland S (2008). Spinnen van de Reijerscamp (Araneae) [The spiders of Reijerscamp (Araneae)]. – Nieuwsbrief SPINED 24: 13-24 Helsdingen PJ van 1999 Catalogus van de Nederlandse spinnen (Araneae). – Nederlandse Faunistische Mededelingen 10: 1-191 Helsdingen PJ van 2016 Catalogus van de Nederlandse spinnen. Versie 2016.1. – Internet http://www.eis-nederland.nl/Portals/4/ Werkgroepen/Spinnen/Spinnencatalogus%202016.1.pdf Larsen P & Bøggild O 1970 Faunistic notes on Danish spiders (Ara- neae). I. – Entomologiske Meddelelser 38: 303-347 Lecigne S 2016 Atlas préliminaire des araignées Araneae du Nord et du Pas-de-Calais. – Le Héron 48(for 2015): 1-236 Locket GH&Millidge AF 1953 British spiders.Vol. II. Ray Society, London. 449 pp. Maelfait J-P, Baert L, Janssen M & Alderweireldt M 1998 A Red list for the spiders of Flanders. – Bulletin de l'Institut Royal des Sciences Naturelles de Belgique Entomologie 68: 131-142 Mikhailov KG 1996 A checklist of the spiders of Russia and other ter- ritories of the former USSR. – Arthropoda Selecta 5(1/2): 75-137 Mikhailov KG 1997 Catalogue of the spiders of the territories of the former Soviet Union (Arachnida,Aranei). Zoological Museum of the Moscow State University, Moscow. 416 pp. Mikhailov KG 2013 The spiders (Arachnida: Aranei) of Russia and adjacent countries: a non-annotated checklist.Arthropoda Selecta, Supplement 3, KMK Scientific Press Ltd., Moscow. 262 pp. Mikhailov KG&Trushina EE 2013 On the spider fauna (Arachnida: Aranei) of the Mordovian State Reserve, Russia: preliminary results. – Arthropoda Selecta 22: 189-196 Milasowszky N & Hepner M 2017 Die Spinnenfauna (Arachnida, Araneae) verwilderter Ziergrünflächen auf der Dachterrasse des Biozentrums Althanstraße (Wien, Alsergrund). – Acta ZooBot Austria 154: 145-164 Müller H-G 1984 Zur Variabilität der Kopfformen bei Zwergspin- nenmännchen. Über Diplocephalus latifrons „fallaciosus“ (Bertkau 1883) und Troxochrus scabriculus „cirrifrons“ (Cambridge 1871) (Arachnida: Araneida: Linyphiidae).– Entomologische Zeitschrift 94: 347–350 Müller F & Schenkel E 1895 Verzeichnis der Spinnen von Basel und Umgegend. – Verhandlungen der Naturforschenden Gesellschaft in Basel 10: 691-824 Oger P 2018 Les araignées de Belgique et de France. – Internet: https://arachno.piwigo.com (25.11.2018) Otrembnik U 1978 Untersuchungen zur Spinnenfauna der Altrhein- landschaft um Grietherbusch/Niederrhein. – Abhandlungen aus dem Landesmuseum für Naturkunde zu Münster in Westfalen 40(1): 1-56 Pickard-Cambridge O 1860 Descriptions of two British spiders new to science. – Annals and Magazine of Natural History (3) 5: 171- 174 – doi: 10.1080/00222936008697198 Pickard-Cambridge O 1871 Descriptions of some British spiders new to science, with a notice of others, of which some are now