The world's fastest spider tops 3.5 metres per second

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  Evolutionary biomechanics of maximum running speed in spiders (Araneae)    Abstract Background Maximum running speed is a central performance trait, linking morphology, physiology and behaviour to fitness. It is shaped by physical capacity and ecological selection but may also be constrained by ancestry. To examine how these forces interact across macroevolutionary timescales, we conducted an allometric study in a hyper-diverse arthropod taxon—spiders (Araneae). Results Drawing on running performance data for 258 species from 64 of the 139 extant spider families, we integrated phylogenetic comparative methods and biomechanical modelling to disentangle the effects of body size, ancestry, leg morphology, ecological guild and preferred locomotor orientation. Maximum running speed varied substantially, both across body mass and among species of similar body mass. By accounting for body mass with a recent biomechanical model, we show that size-specific performance carries ...

A new species of Harpactocrates Simon, 1914 (Araneae: Dysderidae) from Cantabria, Spain

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A new species of Harpactocrates Simon, 1914 (Araneae: Dysderidae) from Cantabria, Spain

Abstract 

A new species of Harpactocrates Simon, 1914 is described from Cantabria, northern Spain as Harpactocrates trenti sp. n. The species is closely related to H. ravastellus Simon, 1914, but can readily be distinguished by the more globular tegulum and a longer, hook-shaped embolus. Female specimens also show a characteristic configuration of the valve folds, visible through the cuticle as two anteriorly diverging lines. Detailed morphological descriptions, images of genital structures, and distribution data are provided. The discovery of H. trenti sp. n. increases the known Iberian representatives of the genus to nine species and highlights the need for further sampling in poorly surveyed regions, where additional undescribed taxa may occur.

Narro-Martín, A. J. (2026). A new species of Harpactocrates Simon, 1914 (Araneae: Dysderidae) from Cantabria, Spain. Arachnology 20(5): 693-698.