Scanning electron microscope and light microscope studies show that each side of the Hyptiotes cavatus female genitalia has a spherical gland and a copulatory bursa which terminates in a long, looped sperm duct. Both components have adjacent openings into the vagina. The lack of secretory tissue associated with sperm ducts suggests that accessory glands function in sperm activation or another aspect of fertilization. A broad, median vaginal invagination with no direct connection to other components nor any associated secretory tissue appears during mating to accommodate the unusually long median apophysis spur of the male's pedipalpus. Separate bursal and sperm duct openings categorize this species as entelegyne, but the proximity of these openings suggests that Hyptiotes typifies an early transitional state in spider female genitalia. Because of anatomical complexity, internal features of the female genital apparatus of Hyptiotes Walckenaer, 1937 have been contested (Muma & Gertsch, 1964; Opell, 1979; Wiehle, 1927). Although the problem stems largely from unresolved details, its solution bears on the larger issues of the evolution of spider genitalia and their use in phylogeny and classification. Primitive (haplogyne) genitalia consist of single or paired blind spermathecae that connect to the vagina near its opening, whereas advanced (entelegyne) genitalia feature a unidirectional system with the opening of each commonly paired copulatory bursa leading to a seminal receptacle (spermatheca) which empties via a fertilization duct into the vagina (Baum, 1972; Brignoli, 1975; Cooke, 1970; Kraus, 1978). In haplogynes, the male intromittent organ (embolus of the pedipalpus) is inserted into the vagina; in entelegynes, it enters one of the secondary or displaced openings on the posterior or ventral surface of the female genital region. Although haplogyne and entelegyne conditions have been used to separate 1 I thank C. Bradford Calloway for help with histological techniques. National Science Foundation Grant DEB-8011713 supported scanning electron microscope use. TRANS. AM. MICROSC. Soc., 102(2): 97-104. 1983. ? Copyright, 1983, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.141 on Sun, 11 Dec 2016 04:30:54 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC. major spider taxa (Gerhardt & Kastner, 1938; Kaestner, 1968; Kaston, 1948; Simon, 1892; Wiehle, 1953), such schemes have not received complete acceptance (Bonnet, 1959; Bristowe, 1938; Lehtinen, 1967; Levi, 1982; Petrunkevitch, 1933). Some workers have considered the possibility of an intermediate or semientelegyne condition (Brignoli, 1975, 1978; Wiehle, 1967), and others view the entelegyne condition as potentially convergent (Opell, 1979; Platnick, 1975; Shear, 1978). The Uloboridae show that a single, universally recognized family can embrace members with both haplogyne and entelegyne female genitalia and that these grades of organization, however useful in understanding spider evolution, are less useful in higher classification than was traditionally thought. Although most of its members are clearly entelegyne, the family's most primitive genera, Tangaroa Lehtinen, 1967 and Waitkera Opell, 1979, have haplogyne female genitalia (Opell, 1979, 1983). Unless one considers their genitalia reduced or Uloboridae as the sister group of all other entelegyne spider families, at least one case of entelegyne convergence