Body size has always been the focus of several ecological studies because of its undeniable influence on other life history traits. Traditional representations of body size in arthropods typically rely on linear measures such as total body length or the length of specific body parts that can be used to represent body size. These measures offer simplicity compared to more complex alternatives (for example., dry mass), and as with scorpions, technical challenges remain for arthropods with complex body structures. In these animals, accurate measurements often require extensive manipulation, such as stretching body parts. Given the difficulties associated with direct measurements of scorpion total length and carapace length (two common indicators of body size within the group), this study phylogenetically determined the juvenile size length of scorpions. We evaluate the ability of seven simple linear measures in predicting measures of . framework. Prediction equations derived from a phylogenetic mixed linear model fitted based on a Bayesian framework were implemented into a custom R function that can be applied to size prediction for a wide range of scorpions. Overall, accurate prediction of total length and carapace length can be achieved using any of the studied traits as a single predictor. However, the most accurate prediction of total length was obtained using the length of posterior chromosome segment V, and the best prediction of carapace length was obtained using Telson length. Adding a second predictor did not significantly affect the quality of size predictions. This indicates that there is no need to increase the complexity of the model by incorporating additional predictors to achieve accurate size estimation. We discuss the technical advantages and limitations associated with each linear measurement. In conclusion, this study expands the repertoire of methods available to accurately estimate body size in scorpions, especially when body size information is only available indirectly through allometric relationships.
Förster SÍA. 2025. Scorpion body size prediction: a phylogenetic comparative examination of linear measurements of individual body parts. PeerJ 13:e18621 https://doi.org/10.7717/peerj.18621
