PATTERN AND DURATION OF COPULATION IN WOLF SPIDERS (ARANEAE, LYCOSIDAE)

The temporal patterns of insertion of male palps, expansion of the hematodocha and duration of copulation are reported for 10 species of Schizocosa Chamberlin 1904, three species of Rabidosa Roewer 1955, one species of Gladicosa Brady 1986, one species of Hogna Simon 1885, two species of Isohogna Roewer 1960, one species of Trochosa C.L. Koch 1848, one species of Geolycosa Montgomery 1904, two species of Arctosn C.L. Koch 1848, three species of Alopecosa Simon 1885 and six species of Pardosa C.L. Koch 1847. In all species of Schizocosa examined so far, males showed a pattern composed of a series of insertions with one palp followed by a switch to the opposite side and a separate series of insertions with the other palp. During each insertion there was a single expansion of the hematodocha. These copulations generally lasted from 1-4 hours. Males of Gladicosa bellamyi (Gertsch & Wallace 1937) and Hogna georgicola (Walckenaer 1837) likewise showed a series of insertions on one side followed by insertions on the other side, with a single expansion of the hematodocha with each insertion. Males of Arctosa littoralis (Hentz 1844), A. sanctaerosae Gertsch & Wallace 1935 and Geolycosa rogersi Wallace 1942 each copulated by alternating palps with a single insertion and single expansion of the hematodocha. The alternating pattern of insertions was also seen in Rabidosa rabida (Walckenaer 1837), R. hentzi (Banks 1904) and R. punctulata (Hentz 1844). lsohogna lenta (Hentz 1844) (a single individual) alternated between multiple expansions of the hematodocha during one insertion and alternating sides with a single insertion and expansion per side. A second member of Isohogna showed a single insertion on one side with multiple expansions of the hematodocha. Comparisons with published descriptions of copulatory pattern suggest that Schizocosa and Trochosa Koch 1848 may form a monophyletic clade in the "Trochosa group" of the Lycosinae. The copulations that involved multiple insertions of the male's palp on one side with a single expansion per insertion were long copulations (1-4 hours). This may provide for multiple opportunities of in copula courtship. Arctosa copulations were very short (18-46 sec), while the Geolycosa copulations were relatively short (5-7 min). Thus, the copulations of the burrowing spiders were much shorter than the nonburrowing spiders. Copulatory behavior in spiders has long fascinated arachnologists (Clerck 1757 in Kaston 1936; Montgomery 1903, 1909; Bristowe 1926; Gerhardt & Kaestner 1937; Savory 1928; other references in Bonnet 1945; Robinson 1982) partly because there is an impressive array of copulatory positions and patterns. Also, in spiders, the potential for sexual cannibalism exists (Arnqvist 1992; reviewed in Elgar 1992), strongly reinforcing the need for clear communication both before and during copulation. Although there have been numerous studies on copulatory behavior in a variety of spiders, relatively few have focused on the patterns of insertion of the male palp during copulation in the Lycosidae (Engelhart 1964; Rovner 1973, 1974; Costa & Sotelo 1994). We here present the patterns of palpal insertion, hematodochal expansion and duration of copulation seen in numerous lycosid species. We also present the first attempt to look at these behaviors in spiders in a phylogenetic context. 4Present address: Dept. of Biology, Rhodes College, 2000 N. Parkway, Memphis, Tennessee 381 12 USA In 'piders (Lycosidae)7 the 5Present address: Dept. of Biological Science, M.L. mounts the female so that they face opposite 6., Univ. of Cincinnati, Cincinnati, Ohio 45221 directions, and the ventral surface of the anUSA terior portion of the male's prosoma is against STRATTON ET AL.---COPULATORY PATTERN IN WOLF SPIDERS 187 the dorsal surface of the female's abdomen. The relative positions of males and females in copula were described by Gerhardt & Kaestner (1937) who categorized five different copulatory positions for spiders. The position described for wolf spiders (above) is also seen in pisaurid genera Thalassius Simon 1885 (Sierwald 1988), Dolomedes Latreille 1804 (Arnqvist 1992), and Pisaurina Simon 1898 (Bruce & Carico 1988) and Agelenidae (Fraser 1986; Gering 1953; Foelix 1982), as well as most "advanced" wandering spiders, including Philodromidae, Clubionidae and Salticidae (Foelix 1982). The Pisaurina shows the same position, but with both spiders hanging from ; silken thread during cbpulation. Once mounted, the lycosid male touches the anterior end of the female's abdomen, causing her to rotate the abdomen. He then scrapes the side of the female's abdomen with his palp, and most times the palp engages with the epigynum apparently by the median apophysis of the palp catching on the epigynal hood (unpubl. data, based on examination of high magnification videorecording from the ventral aspect of Schizocosa sp. nr. crassipes [Walckenaer 18371). The right palp engages with the right side of the epigynum; the left palp engages the left side. Once engaged, the male expands the hematodocha which causes the embolus to coil into the female's copulatory duct and at some point, sperm is transferred. The timing of sperm transfer in groups with multiple insertions or with multiple hematodochal inflations has never been determined for any species. We call the physical act of the coupling of the male palp with the female epigynum an "insertion". The hematodocha may expand one or more times during a single insertion. If the male spider inserts the same palp multiple times before switching sides, a "series" of insertions or "multiple insertions" occurs (Rovner 1974). Behavior has provided useful characters in the phylogenetic studies of the Lycosoidea clade. Carico (1986, 1993) looked at method of egg sac transport, structure of egg sac seam, method of maternal care, silking of female during copulation, the structure of the web retreat, reattachment of the egg sac, as well as the structure of the nursery web. Merrett (1988) used several behavioral traits in placing Ancyclometes bogotensis (Keyserling 1876) in the Pisauridae. Griswold (1993) used two behavioral characters (nursery web and method of egg sac transport) in his phylogenetic analysis of Lycosoidea. Copulatory pattern has not yet been used in phylogenetic contructions as it has been reported only for a few species outside of the Lycosidae. In 1973, Rovner suggested that Gertsch & Wallace's (1937) placement of Schizocosa avida (Walckenaer 1837) into the genus Schizocosa was supported by the copulatory pattern demonstrated by that species (Rovner 1973). Rovner noted that the pattern of palpal insertions in Rabidosa rabida was qualitatively distinct from the patterns demonstrated by Schizocosa, particularly S. saltatrix (Hentz 1844) observed by Rovner (1972) and S. bilineata (Emerton 1885) and S. ocreata (Hentz 1844) observed by Montgomery (1903). This was the first time copulatory behavior was used to investigate taxonomic placement in Schizocosa. Costa & Sotelo (1994) provided a brief review of copulatory patterns in wolf spiders and suggested that generally there are few differences in copulatory patterns among closely related species, but the differences become more notable at higher taxonomic levels. We here report on the patterns of palpal insertion, hematodochal expansion, and copulation duration that we have observed in 10 species of Schizocosa. For many of these, we have observed copulatory behavior in several populations from a wide geographic range. We also report on the copulatory pattern seen in eight other North American lycosid species representing five genera. Additional data are provided for Pardosa, Hogna, Geolycosa (Dondale & Redner unpubl. data), for Sosippus Simon 1888 (Rovner unpubl. data) and for Alopecosa and Hygrolycosa Dahl 1908 (Kronestedt 1979, unpubl. data) and are discussed in the context of our observations. While this is still a relatively small proportion of the 2200 species of wolf spiders that exist worldwide (Coddington & Levi 1991), the patterns observed so far warrant some discussion. We also hope this report may stimulate other researchers to examine more species of lycosids for patterns in copulatory behavior.