Description of the agonistic behaviors of Loxosceles laeta, L. hirsuta and L. intermedia (Araneae: Sicariidae)

Abstract

The evolutionary groups of species of Loxosceles Heinecken & Lowe, 1835, besides having morphological characters in common, may also show similar behaviors. The present study describes the agonistic behavior of males of members of the spadicea group - Loxosceles intermedia Mello-Leitão, 1934 and L hirsuta Mello-Leitão, 1931 - and the laeta-group - L laeta (Nicolet, 1849) - that occur in the state of Paraná. In experiments with paired males, an intruder male was placed in the web of a resident male web, and the motor patterns displayed were described and quantified. Males of all three species showed confrontation, defense and combat behaviors. The combat was ritualized and related to peculiarities of each species, while sharing the signaling of strength and size. The motor patterns shown during agonistic behavior were similar to those used in sexual behavior. The motor patterns of L. intermedia and L. hirsuta were more similar to each other and different from L laeta, suggesting a relationship to the evolutionary group radiation.