Arthrolycosa Harger, 1874

Dunlop 1, Jason A., 2023, The first Palaeozoic spider (Arachnida: Araneae) from Germany, PalZ 2023, pp. 1-8 : 3

Genus Arthrolycosa Harger, 1874

Type species. Arthrolycosa antiqua Harger, 1874

Included species. A. wolterbeeki sp. nov.

Taxonomic remarks. Two arthrolycosid genera were recognised by Selden (2021). Arthrolycosa Harger, 1874 was redefined as having a carapace about as long as wide, with a distinct ridge behind the fovea (the depression in the centre of the carapace) and legs I and IV being longer than legs II and III. Protolycosa Roemer, 1865 was redefined on a carapace longer than wide and somewhat pointed anteriorly with a recurved posterior margin. The fovea may or may not be a deep pit, and leg I is characteristically shorter than the other legs. According to Selden (2021), both genera express rows of tubercles long the posterior margins of the opisthosoma (as does the Piesberg fossil), although earlier workers such as Petrunkevitch (1955) cited this as diagnostic for Protolycosa only. Using these criteria, the full proportions of the carapace in the Piesberg fossil are uncertain, but the preserved curvature suggests that it was probably rather short and certainly not longer than wide. Also, the carapace posterior margin is not noticeably recurved. The preserved appendages suggest that leg I was not shorter than the succeeding legs, and a IV> I> II> III leg formula (from longest to shortest) seems likely. For these reasons, the new fossil is most consistent with Arthrolycosa , confirming the provisional report of the presence of this genus at Piesberg by Leipner et al. (2021).