Evidence for a thoracic crop in the workers of some Neotropical Pheidole species (Formicidae: Myrmicinae).

The ability of ant colonies to transport, store, and distribute food resources through trophallaxis is a key advantage of social life. Nonetheless, how the structure of the digestive system has adapted across the ant phylogeny to facilitate these abilities is still not well understood. The crop and proventriculus, structures in the ant foregut (stomodeum), have received most attention for their roles in trophallaxis. However, potential roles of the esophagus have not been as well studied. Here, we report for the first time the presence of an auxiliary thoracic crop in Pheidole aberrans and Pheidole deima using X-ray micro-computed tomography and 3D segmentation. Additionally, we describe morphological modifications involving the endo- and exoskeleton that are associated with the presence of the thoracic crop. Our results indicate that the presence of a thoracic crop in major workers suggests their potential role as repletes or live food reservoirs, expanding the possibilities of tasks assumed by these individuals in the colony. Our contribution emphasizes the utility of combining data from external and internal morphology to better understand functional and behavioral mechanisms.

A species-level association in Pheidole Westwood (Hymenoptera: Formicidae) ants with a parasitoid wasp of the genus Orasema Cameron (Hymenoptera: Eucharitidae) in Brazil

Abstract Eucharitid wasps are exclusive parasitoids of ants and certain groups of eucharitids have specific associations with their hosts. This type of specificity is widely documented in more inclusive groups (subfamilies and/or genus-groups). However, we do not know if this specificity occurs in less inclusive groups (such as species or populations) or if it is more strongly influenced by local and/or regional environmental constraints. We provide a new association record between Pheidole gibba Mayr, 1887 and Orasema chunpi Burks, Heraty & Dominguez, 2018, while expanding their known distribution to the Brazilian state of Bahia.