Ultrastructure of attachment specializations of hexapods (Arthropoda): evolutionary patterns inferred from a revised ordinal phylogeny Author R. G. Beutel Author S. N. Gorb text J. Zool. Syst. Evol. Research 2001 39 177 207 journal article 10.1046/j.1439-0469.2001.00155.x 95b3d62f-8fcc-4088-873f-b33f4a63d3fc 2360323 20 Psocoptera The tarsus is two­ or three­segmented ( Weidner 1972 ). Euplantulae and arolium are lacking. A seta which is slightly extended distally (‘saugerartiger Pulvillus’; Weidner 1972 ) is present on the toothed or simple claws ( Fig. 3j ).