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Characteristics of the complicated palpal organs of male spiders are widely used in taxonomy. In species with a simple and unspecialized palpus, a gross observation is unusually satisfactory, but in species in which the palpal organ is complicated and specialized, many spider taxonomists expand the palpus in order to observe the structural details. Because the process of expansion has never been critically examined, there is little uniformity in figures and descriptions of new species. In many publications on spider taxonomy figures are of expanded palpi; in other publications, figure are of unexpanded palpi. The present study is based on 29 species of spiders with palpi of various degrees of complexity. Palpi were expanded by placing them for 6-8 hours in 10% KOH solution, and then quickly transferring them to distilled water. After expansion, the palpi were compared with unexpanded palpi from individuals collected at the same locality and time. It was concluded that the process of expansion is most useful in species having a complicated palpapl organ, but conditions, such as a reduction of the hematodochae, sometimes result in limited usefulness of the process even though the palpus is complex. In species having palpi of an intermediate degree of complexity, the experimenter must use his own judgment about the process being worthwhile. In species with primitive or simplified palpi, the process is rarely useful.



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Department Name

UNM Biology Department

First Committee Member (Chair)

Clarence Clayton Hoff

Second Committee Member

John W. Beakley

Third Committee Member

William Wayne Johnson

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Biology Commons