The Taxonomic Significance of the Spider Trochanter1

Abstract

The following parts of the trochanter were named for this study: the circulus, a sclerotized ring; the setal carina, a thickened rim bearing a row of stout setae at the distal edge of the circulus; the cuneus, a ventral, wedge-shaped, glabrous and lightly sclerotized part of the circulus; the cuneal disk, a circular, swollen, membranous area of the cuneus which is characteristic of the family Pholcidae; and the limulus, the heavily sclerotized, raised border of the cuneus which is the "notched trochanter" of many authors. The distal border of the limulus differs in shape among spiders. In most of them (22 out of 39 families, and part of the genera of 7 others) it is rounded to broadly truncate. It is deeply notched in the Pisauridae, Lycosidae, and Heteropodidae; less so in the Oxyopidae, Zoropsidae, and Homalonychidae; and much less in the Zodariidae. The notch occurs in 1 or more genera of Linyphidae, Clubionidae, Thomisidae, Agelenidae, Argiopidae, and Dictynidae. Although Petrunkevitch, in writing of the Salticidae, referred to "notched trochanters," no limuli were found notched in this family. Notched limuli occur occasionally in the Agelenidae, on the fourth or the third and fourth pairs, but never on all 4 pairs. As the genus Barrisca Chamberlin and Ivie has all limuli deeply notched and the tarsal trichobothria irregularly placed, this necessitates its placement in the subfamily Rhoicininae of the Pisauridae. || ABSTRACT AUTHORS: Author