NEW article available today…
Wolff J., Seiter M. & S. Gorb (2015) Functional anatomy of the pretarsus in whip spiders (Arachnida, Amblypygi). Arthropod Structure & Development, .
Whip spiders (Amblypygi) are a small, cryptic order of arachnids mainly distributed in the tropics. Some basal lineages (families Charinidae and Charontidae) have large adhesive pads on the tips of their six walking legs. The present study describes the macro- and ultrastructure of these pads and investigates their contact mechanics and adhesive strength on smooth and rough substrates. Furthermore, the structure of the pretarsus and its kinematics are compared in Charon cf. grayi (with an adhesive pad) and Phrynus longipes (without an adhesive pad). The adhesive pad exhibits an elaborate structure with a unique combination of structural features of smooth and hairy foot pads including a long transversal contact zone performing lateral detachment, a thick internally-branched cuticle with longitudinal ribs and hexagonal surface microstructures with spatulate keels. The contact area of the pad on smooth glass is discontinuous due to the spatulate microstructures with a discontinuous detachment, which could be observed in vivo by high speed videography at a rate of up to 10000 fps. Adhesive strength was measured with vertical whole animal pull-off tests, obtaining mean values between 55 and 200 kPa. The occurrence of viscous lipid secretions between microstructures was occasionally observed, which, however, seems not to be a necessity for a good foothold. The results are discussed in relation to the whip spider’s ecology and evolution. Structure-function relationships of the adhesive pads are compared to those of insects and vertebrates.
New paper published in Zootaxa this week:
Seiter M., Wolff J. & C. Hörweg (2015) A new species of the South East Asian genus Sarax Simon, 1892 (Arachnida: Amblypygi: Charinidae) and synonymization of Sarax mediterraneus Delle Cave, 1986. Zootaxa, 4012(3): 542-552.
Abstract: A new species of the whip spider genus Sarax Simon, 1892 from Cebu Island in the Philippines is described: Sarax huberi sp. nov. With the description of this species, the diversity of the genus is increased to three species in the Philippines. Some additional data on their natural environment and their specific habitat are presented and compared with sibling species. The synonymization of Sarax mediterraneus Delle Cave, 1986 with Sarax buxtoni (Gravely, 1915) is carried out.