Bulletin of Insectology 79: 77-88, doi: 10.3897/bull.insectology.187568
Shared allometric trajectories but contrasting sexual size dimorphism in Osmoderma barnabita and Rosalia alpina from the Eastern Carpathians, Romania
Marian D. Mirea‡§, Iulia V. Miu‡, Lavinia C. Pindaru§‡, Steluta Manolache‡, Laurentiu Rozylowicz‡‡ University of Bucharest, Center for Environmental Research, Bucharest, Romania§ Doctoral School in Geography Simion Mehedinti - Nature and Sustainable Development, University of Bucharest, Bucharest, Romania
Corresponding author: Marian D. Mirea ( dumitru-marian.mirea@geo.unibuc.ro ) Academic editor: Serena Magagnoli © Marian D. Mirea, Iulia V. Miu, Lavinia C. Pindaru, Steluta Manolache, Laurentiu Rozylowicz. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Citation:
Mirea MD, Miu IV, Pindaru LC, Manolache S, Rozylowicz L (2026) Shared allometric trajectories but contrasting sexual size dimorphism in Osmoderma barnabita and Rosalia alpina from the Eastern Carpathians, Romania. Bulletin of Insectology 79: 77-88. https://doi.org/10.3897/bull.insectology.187568 |  |
Abstract
Sexual size dimorphism and morphometric variation provide valuable insights into population ecology, habitat quality, and evolutionary processes in insects. However, morphometric data for saproxylic beetles remain limited across much of Europe, particularly in the Carpathian Mountains of Romania, which host some of the largest contiguous forest ecosystems and are a major biodiversity hotspot for these species, despite their high conservation importance. We investigated sexual size dimorphism patterns and allometric relationships in two protected saproxylic beetles, Osmoderma barnabita Motschulsky, 1845 (Scarabaeidae) and Rosalia alpina Linnaeus, 1758 (Cerambycidae), from the Putna-Vrancea Natural Park, Romania. Between 2022 and 2025, we captured 776 Osmoderma barnabita and 268 Rosalia alpina individuals using pheromone-baited traps and measured body length, body width, and fresh mass. Osmoderma barnabita exhibited weak male-biased sexual size dimorphism, with males slightly larger in body length (+3.4%) and body mass (+5.0%), while body width showed no significant difference between sexes. In contrast, Rosalia alpina displayed female-biased sexual size dimorphism across all traits, with the strongest dimorphism in body mass (+13.2%). Standardized Major Axis regression showed positive allometry of body width relative to body length in both species, indicating increased robustness with size. Body mass scaled isometrically with body length, with no sex-specific differences in allometric slopes, suggesting that sexual size dimorphism reflects uniform size shifts along shared developmental trajectories. Linear Discriminant Analysis achieved only moderate classification accuracy (63.5% for Osmoderma barnabita; 65.3% for Rosalia alpina), reflecting substantial morphological overlap between sexes. These findings establish baseline morphometric data essential for long-term population monitoring and conservation planning in the Eastern Carpathian forests.
Keywords
Baseline data, morphometrics, pheromone trapping, saproxylic beetles, trait scaling