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Psyche 
[Vol. 88 
Conclusion 
The use of stridulation to produce sound by P. mystaceus appears 
to represent a third method of communication for salticids (a fourth 
method, if the tarsal percussion of Euophrys frontalis is a valid 
communicatory process). Despite the fact that females used for the 
present research failed to respond favorably to courtship by their 
sibling male, the behavioral and morphological evidence in the male 
of a functional role for sound production during courtship is 
substantial . 4 
Summary 
Males of Phidippus mystaceus have a stridulatory organ located 
on the tarsal and tibial segments of the palpi. This organ is 
employed by males in the potential or actual presence of adult 
females, and forms the most significant part of courtship by males. 
The mechanics of stridulation are somewhat similar to those of 
lycosids, and as with the lycosids, substrate vibrations may be the 
most important component of stridulation. Evolution of sound 
production by P. mystaceus is hypothesized to have occurred in 
conjunction with the evolution of cryptic coloration. Sound produc- 
tion is thought to extend the males’ communicatory distance, 
compensating for fewer visual identification opportunities due to 
the spiders’ cryptic coloration. 
Acknowledgments 
I would like to give special thanks to the following: Dr. Robert 
Paul for his help in sound recording and producing the audiospec- 
trogram; Dr. Jonathan Reiskind for the S. E. M. photomicrographs. 
Thanks are also due; Mr. John Thorne and Mr. Stan Blomely for 
4 Two antepenultimate P. mystaceus were collected by G. B. Edwards, 28 July 1979, 
Ocala National Forest, Marion Co., Florida, beating young scrub live oaks, and 
reared to maturity (October, 1979). Although these specimens were collected and 
reared after the research on the Oklahoma specimens was completed, and the 
courtship was neither filmed nor recorded, a courtship and mating was observed for 
this pair. Courtship appeared in all respects to be identical to that of the Oklahoma 
male, including type of sound, stance, and the rapid upward flicking of the tarsi and 
metatarsi at less than 1 cm distance from the female. Mating occurred in the female’s 
nest and lasted 87 minutes until the female left the nest. Upon separating, the male 
renewed courtship, initially showing a single lateral stepping sequence as in the 
Oklahoma male. The female avoided the male, and the pair was separated. 
