1981] 
Edwards — Phidippus mystaceus 
201 
tibia facing a cymbial plectrum, the reverse of the condition in P. 
mystaceus. The file system of P. mystaceus appears to consist of 2 
types of adjacent file fields which blend into one another. Within the 
concavity is a fan-shaped file, while along the distal edge of the 
concavity is a linearly-arranged file similar to lycosid files. Neither 
file is as well-defined as the lycosid files. The individual ridges of P. 
mystaceus ’ files are rounded, whereas those of lycosids have distinct 
edges; however, in P. mystaceus, both types of file are overlaid with 
numerous short ridges of variable length (Fig. 2). 
Fig. 1. Distal tip of palpus of male P. mystaceus showing ring of macrosetae (M) 
encircling whorled chemotactile setae (W). On extreme left are scale-like setae (S) 
which form part of a white and/or yellow spot which probably contributes to the 
overall visual stimulus of a courting male (100X). Note the greater number of 
macrosetae on the ectal edge (E); see text for explanation. The curved macrosetae 
(extreme right) at the tip of the cymbium first contact the substrate and may facilitate 
the backwards sliding motion of the palpi by reducing friction with the substrate. 
