2026/06/03 by Wellen Cristina Alves Bezerra, Glauco Machado · 1 citation
Earth and Planetary Sciences · Biochemistry, Genetics and Molecular Biology · Agricultural and Biological Sciences · #Subterranean biodiversity and taxonomy #Spider Taxonomy and Behavior Studies #Animal Behavior and Reproduction
paper · doi:10.1016/j.anbehav.2026.123614
Male trimorphism occurs in few animal species and remains poorly understood, both in its proximate causes and ultimate adaptive significance. Here, we provide the first evidence of male trimorphism in a Neotropical harvestman. Using modern procedures for morph recognition, we show that Longiperna concolor , previously considered male-dimorphic, actually has three male morphs (alpha, beta and gamma). We also examine the allometric patterns of fourth-leg length, a trait used as a threat device in male–male contests. Our results show that alphas exhibit hypoallometry, betas exhibit hyperallometry and gammas exhibit isometry. Reanalysis of previously published behavioural data revealed that alphas are the primary harem holders and the most frequent contestants, but a subset of betas also holds harems and engages in territorial contests. In contrast, gammas were never observed defending harems or engaging in contests. We propose that a gene-by-environment interaction involving two developmental switchpoints is the most plausible mechanism underlying male trimorphism in this species. The morphs are associated with three mating tactics: alphas rely on resource defence, gammas on sneak copulations and betas likely adopt a flexible ‘jack-of-all-trades’ tactic. Future work should test whether exaggerated traits in hemimetabolous species favour male trimorphism and whether intermediate males show greater behavioural flexibility.