Arachnologische Mitteilungen 56

Arachnologische Mitteilungen / Arachnology Letters 56: 48-54 Karlsruhe, September 2018 Taxonomical history Westring (1851) first described Troxochrus scabriculus (sub Erigone scabricula ) based on male and female specimens from Sweden. A decade later, Pickard-Cambridge (1860) described Troxochrus scabriculus sub Walckenaera aggeris from southern England and provided the following information with regard to the record date and locality (on page 174): “Adult males and females of this species were discovered by myself in ab- undance, during the summer of 1859, at the roots of grass and underneath rubbish on dry bank-sides, near Church Town, Southport, Lancashire”. Later, Pickard-Cambridge (1871) described a further new species, sub Walckenaera cirrifrons , based on a single male specimen, which clearly came from the same material in which he originally found T. scabriculus a decade earlier: “An adult male of this spider was captured, in company with W. aggeris (Camb.), at Southport, Lancashire, at the roots of grass &c., in June 1859.” It is important to note that (i) T. scabriculus and T. cirrifrons came from the same material sampled at the roots of grass in the summer of 1859 near Church Town, Southport, Lancashire; and that (ii) the specimens of T. scabriculus were present in abundant numbers, while only one male specimen of T. cirrifrons was identified in the same samples. Simon (1884: 645) established the genus Troxochrus and was the first to suspect Troxochrus scabriculus of being dimor- phic in the males, consisting of the typical form scabriculus and the second form cirrifrons . Simon stated that: “La forme cirrifrons se trouve toujours mêlée au type, mais elle est par- tout plus rare” [The form cirrifrons is always mixed with the type, but it is everywhere rarer]. More than a quarter of a century later, Pickard-Cam- bridge (1911) reopened the case of T. scabriculus/cirrifrons and attempted to negate the statement of Simon (1884) that T. cirrifrons is a dimorphic male form of T. scabriculus . Although Pickard-Cambridge (1911) acknowledged that “the two spe- cies remarkably differ in the male sex”, he disagreed with the conclusion of Simon (1884), because “Simon relies chiefly, for the identity of scabriculus and cirrifrons , on the two forms being always found together (i.e., at the same time and place); but this I have by no means myself proved to be the fact”. In the same work, Pickard-Cambridge (1911) described the female of T. cirrifrons which he believed to be different from the T. scabriculus female by drawing reference to illus- trations of the epigynes ( T. scabriculus , Plate A, Fig. 18 and T. cirrifrons Plate A, Fig. 19). Curiously, Pickard-Cambridge (1911) in his description to Plate A, placed a question mark in the figure captions before both species names, perhaps indi- cating uncertainty about any differences between the females. Nevertheless, Pickard-Cambridge (1911) managed to con- clude that “on the whole T. cirrifrons still seems to me to be a distinct species from T. scabriculus ”. Oddly, Simon (1926), in a work which was completed by Lucien Berland and Jean-Louis Fage two years after Simon’s death in 1924, recanted the original opinion of Simon (1884). Thus, in the identification key for the genus Troxochrus , T. scabriculus and T. cirrifrons were treated as different species (Simon 1926: 369). Nevertheless in our opinion, the drawings of the epigynes in Simon (1926) ( T. scabriculus , Fig. 652, T. cirrifrons , Fig. 655) are as inconclusive as those in Pickard- Cambridge (1911). Although T. scabriculus and T. cirrifrons were henceforth recognized as different species in World Spider Catalogs (see Roewer 1942, Platnick 1989), many arachnologists continued to infer that T. cirrifrons is perhaps a subspecies of the typical form T. scabriculus (e.g. Bristowe 1939: 75), or that it is a va- riety (e.g. Wiehle 1960: 466, Locket & Millidge 1953: 264), or indeed a dimorphic form (Thaler 1986: 496) or at least a sibling species (Aakra et al. 2016).With regard to the females, Wiehle (1960: 466) stated that female specimens which were found with the two male forms cannot be distinguished from each other, not even with detailed vulva preparation. Conse- quently, in one of his following works,Wiehle (1961: 183) di- A case of dimorphic males in Troxochrus scabriculus (Araneae: Linyphiidae), with notes on synonymy Norbert Milasowszky & Martin Hepner doi: 10.30963/aramit5609 Abstract. Troxochrus cirrifrons (O. Pickard-Cambridge, 1871) is a junior synonym of Troxochrus scabriculus (Westring, 1851). Moreover, Troxochrus scabriculus is a species with dimorphic males, the nominate form is referred to as T. scabriculus forma scabriculus , and the sec- ond morph as T. scabriculus forma cirrifrons . No significant differences are present in the male palps or any sexual characters of these two forms. Likewise, the accompanying females of different populations exhibit no significant differences in general appearance or genitalia. We provide data on the taxonomic history, national checklists, habitat and distribution, as well as phenology to support the synonymy and to verify male dimorphism in Troxochrus scabriculus . Keywords: Austria, dimorphism, linyphiid spider, Vienna Zusammenfassung. Ein Fall von dimorphen Männchen bei Troxochrus scabriculus (Araneae: Linyphiidae), mit Anmerkungen zur Synonymie. Troxochrus cirrifrons (O. Pickard-Cambridge, 1871) ist ein jüngeres Synonym von Troxochrus scabriculus (Westring, 1851). Zudem handelt es sich bei T. scabriculus um eine Species, bei der es zwei männliche Morphen gibt, die Nominatform T. scabriculus forma scabriculus , und die zweite Form Troxochrus scabriculus forma cirrifrons . Es gibt keine erkennbaren Unterschiede in den männlichen Pal- pen zwischen diesen beiden Formen, und auch die Weibchen aus denselben bzw. aus verschiedenen Population weisen keine erkenn- baren Unterschiede im allgemeinen Erscheinungsbild oder in den Genitalien auf. Die Synonymie und der Dimorphismus der Männchen von Troxochrus scabriculus wird durch Daten zur taxonomischen Erfassungsgeschichte und in nationalen Checklisten, zum Habitat und zur Verbreitung sowie zur Phänologie untermauert. Norbert MILASOWSZKY, Martin HEPNER, Department of Integrative Zoology, Univer- sity of Vienna; E-mail: norbert.milasowszky@univie.ac.at, martin.hepner@univie.ac.at submitted 28.5.2018, accepted 28.11.2018, online 6.12.2018