Differences in pedipalp form and size affect courtship behavior in Tityus species

 

Differences in male morphology within the same species have been observed in many species. In a recent paper, Lais Pordeus and Andre Lira show that differences in the male pedipalp chela in Tityus pusillus Lourenço, 2013 (Buthidae) are associated with differences in reproductive behavior. Males with "robust" pedipalp chela performed a higher number of reproductive attempts and female manipulations than than males with "gracile" chela.

Interestingly, the reproductive success of the males in the two groups was quite similar.

Abstract:
This study investigates male pedipalp chela dimorphism and its association with reproductive behaviour in the litter-dwelling scorpion, Tityus pusillus. Using geometric morphometrics, two distinct male morphotypes were identified based on pedipalp chela shape: robust and gracile. These morphotypes were associated with measurable variation in courtship behaviour aspects. Males with robust chelae performed a higher number of reproductive attempts and female manipulations than gracile-chela males, although these differences were not statistically significant. Notably, robust-chela males completed courtship significantly faster than gracile-chelae males (8.03 ± 5.14 minutes vs. 18.40 ± 13.84 minutes), measured as the time until mating successful conclusion. Both morphotypes exhibited similar reproductive success rates (37% and 31%, respectively). These results indicate that robust and gracile differ in courtship dynamics, particularly in courtship duration and patterns of female handling. Variation in female resistance during courtship may help explain why male reproductive behaviours vary. This study documents male chela dimorphism in T. pusillus and reports its correlation with variation in courtship behaviour.

Reference:
Pordeus LM, Lira AFA. Dimorphism in male pedipalps affects the reproductive behaviour in the litter-dwelling scorpion Tityus pusillus Pocock, 1893 (Scorpiones: Buthidae). Invertebrate Reproduction & Development. 2026;Published online 17 Feb 2026. [Subscription required for full text]