Remarkable micro-endemism and high congeneric richness: eight new cave-restricted species of Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from the Brazilian semi-arid

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  Remarkable micro-endemism and high congeneric richness: eight new cave-restricted species of Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from the Brazilian semi-arid Abstract Eight new species of pseudoscorpions belonging to the genus Pseudochthonius Balzan, 1892 are described from the semi-arid region of Brazil. Comprehensive morphological descriptions, diagnostic characters, detailed illustrations, and ecological remarks of the habitats are provided for Pseudochthonius celestialis sp. nov., P. caritas sp. nov., P. patientia sp. nov., P. temperantia sp. nov., P. diligentia sp. nov., P. castitas sp. nov., P. humilitas sp. nov., and P. benignitas sp. nov. In addition, we present a brief discussion of the potential factors underlying the remarkable congeneric species richness observed in this geographically restricted region, as well as the principal threats faced by these species. These findings underscore the importance of conserving caves in order to pr...

A comparison of adhesive performance among six cursorial spider species

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A comparison of adhesive performance among six cursorial spider species

Abstract

The ability to adhere to surfaces is particularly relevant for cursorial predatory arthropods like hunting spiders, which often traverse relatively complex environments characterized by large variation in substrate properties. Here, we evaluated the adhesive performance of six hunting spider species that are common in eastern temperate North America and lack specialized tarsi for climbing smooth or inclined surfaces [Lycosidae: Pardosa lapidicina Emerton, 1885 and Rabidosa rabida (Walckenaer, 1837); Oxyopidae: Oxyopes salticus Hentz, 1845; Pisauridae: Pisaurina mira (Walckenaer, 1837); Dolomedidae: Dolomedes triton (Walckenaer, 1837), and Dolomedes scriptus Hentz, 1845]. We tested adhesion performance as shear load resistance (g) on a glass plate, and as the angle of failure (°) when the plate was gradually inclined relative to horizontal. Average angle of failure and shear resistance differed among species, and shear resistance increased interspecifically with mass. Rabidosa rabida had the highest average angle of failure and shear resistance. Adhesive performance was not related to tarsal index (tarsal contact area per unit mass) for most species, but shear resistance declined with increasing tarsal index in Pardosa lapidicina and Rabidosa rabida. Collectively, these results suggest that, for spiders lacking specialized adhesive tarsi, adhesive performance is largely a function of basic physics, i.e., the interaction of mass and contact area with a substrate.

E. J. Schleff, M. W. Chmielewski, A. Y. Stark, S. P. Yanoviak "A comparison of adhesive performance among six cursorial spider species," The Journal of Arachnology, 53(3), 203-207, (8 June 2026) https://doi.org/10.1636/JoA-S-24-046