Structure and function of the large pronotal horn of the sand-living anthicid beetle Mecynotarsus tenuipes
Article first published online: 16 MAY 2012
© 2012 The Entomological Society of Japan
Volume 15, Issue 3, pages 274–279, July 2012
How to Cite
HASHIMOTO, K. and HAYASHI, F. (2012), Structure and function of the large pronotal horn of the sand-living anthicid beetle Mecynotarsus tenuipes. Entomological Science, 15: 274–279. doi: 10.1111/j.1479-8298.2012.00517.x
- Issue published online: 9 JUL 2012
- Article first published online: 16 MAY 2012
- Received 9 December 2011; accepted 10 January 2012.
- digging behavior;
- digging cost;
- functional morphology
Large insect horns function as antipredator armaments, digging implements and intraspecific combat weapons. The sand-living anthicid beetle Mecynotarsus tenuipes possesses a large horn on the pronotum. Allometric relationships between body size and horn size did not show either a slope of more than 1 or sexual dimorphism, suggesting another function of the horn other than sexual selection via combat. Behavioral observation of individuals using a microvideo camera indicated that the horn is used to dig and move forward in loose sand. Only the horned M. tenuipes could dig into sand, in contrast to the hornless anthicid beetles Stricticollis valgipes and Clavicollis fugiens, which could not dig. When moving in sand, M. tenuipes joins its pronotal horn and head to form a conical shape, with which it pierces into the sand. Then, it opens its horn and head outward to create a space in the sand for forward motion. Although it can dig deeply into sand by repeating these behaviors sequentially, digging speed tends to slow with depth, probably because the weight of the substrate increases.