A Presumptive Pheromone-Emitting Structure in Wolf Spiders (Araneae, Lycosidae)

The occurrence of pheromones in lycosid spiders has long been indicated on behavioural grounds. (For a review on chemical communication in spiders, see Tietjen and Rovner 1982.) There are bioassay evidences for (1) contact sex pheromones deposited on the substrate by females (Bristowe and Locket, 1926; Rovner, 1968; Hegdekar and Dondale, 1969; Richter et al., 1971; Dijkstra, 1976; Robert and Krafft, 1981), (2) contact sex pheromones associated with draglines laid by females (Kaston, 1936; Engelhardt, 1964; Richter et al., 1971; Dondale and Hegdekar, 1973; Tietjen, 1977, 1979b; Tietjen and Rovner, 1980; Robert and Krafft, 1981), (3) contact sex pheromones associated with female integument (Kaston, 1936), and (4) airborne sex pheromones given off by females (Tietjen, 1979a). Candidates for contact pheromone perception are chemosensitive hairs occurring on legs and palps. The number of these hairs is considerably increased in adult males in comparison to immatures and adult females (Tietjen and Rovner, 1980, 1982), and in certain lycosid genera this increase is rather drastic (Kronestedt, 1979a). No site of production and release of pheromones in wolf spiders has so far been found (Tietjen and Rovner, 1982). The present note focuses on a type of structure which is presumably involved in the release of pheromones in this spider family. Studies on courtship behaviour in various lycosid species have been undertaken for supplementing morphological data in taxonomic contexts as well as for finding connections between adult male secondary sex characters and species-specific behavioural elements. Among the species studied, the adult male of Alopecosa cuneata (Clerck) has a unique character in its first tibiae being tumid