Morphology and ultrastructure of the mandibular gland in the ant Brachyponera sennaarensis (Hymenoptera, Formicidae)

Abstract

The 'samsum ant' Brachyponera sennaarensis is an invasive species in Saudi Arabia, where it forms a serious threat because of its painful sting. As part of a morphological survey of the exocrine system of this species, we studied the mandibular gland of males, queens and workers of this species. The gland of males is similar to the common anatomical appearance the mandibular gland has in ants in general, but is considerably different in queens and workers. In both female castes, the secretory cells are grouped in one single cluster, that is surrounded by a thick sheath of connective tissue. The duct cells, that transport the secretion towards the wrinkled reservoir, appear considerably folded. Both the sheath of connective tissue and the folded ducts are considered as a mechanical reinforcement of the gland, although the reason for such reinforcement remains unclear as we are not aware of any peculiar movements of the mandibles in queens and workers. At the ultrastructural level, the secretory cells in all castes are characterized by a well-developed smooth endoplasmic reticulum, which is indicative for the elaboration of a non-proteinaceous and hence possibly pheromonal secretion. The clear structural differences between males and the two female castes, which so far had not been found in other ant species, show that the mandibular gland in B. sennaarensis most likely has a different caste-dependent function.

The burden of bites and stings management: Experience of an academic hospital in the Kingdom of Saudi Arabia

“…Cases with history of recurrent anaphylaxis following black (samsum) ant stings in Saudi Arabia have been reported in the literature ( Al-Shahwan et al, 2006 ). Morphology and ultrastructure of the venom gland of queens and workers of the samsum ant Brachyponera sennaarensis , which is known for its very painful sting ( Billen and Al-Khalifa, 2018 ).…”

Morphology of the mandibular gland of the ant Paraponera clavata (Hymenoptera: Paraponerinae)

“…The morphology of the mandibular gland of P. clavata is similar to that of another species, the Ponerinae Dinoponera grandis (Perty), as to the location and shape of the reservoir (Hermann et al, ). However, the clustered arrangement of globular glandular cells of P. clavata differs from the ovoid cell clusters of the Formicinae Polyergus rufescens (Latreille) (Grasso et al, ) and species of Calomyrmex (Emery) (Brough, ); the Myrmicinae Atta sexdens (Forel) (Amaral & Machado‐Santelli, ) and Monomorium pharaonis (Linnaeus) (Boonen, Eelen, Børgesen, & Billen, ); and the Ponerinae Dinoponera gigantea (Perty) (Caetano et al, ), Pachycondyla striata (Smith) (Serrão et al, ), and Brachyponera sennaarensis (Mayr) (Billen & Al‐Khalifa, ).…”

“…This can either appear with tightly packed or loosely arranged microvilli that surround the central cuticular canal, of which the loosely arranged form has been interpreted as a temporary storage space at the cellular level (Billen & Schoeters, ; Billen, Ito, Maile, & Morgan, 1998, Boonen et al, ). Whereas the duct cells of mandibular glands in other species usually are mainly straight, they appear remarkably folded in queens and workers of Brachyponera sennaarensis (Billen & Al‐Khalifa, ).…”

Morphology and closing mechanism of the mandibular gland orifice in ants (Hymenoptera: Formicidae)

“…The paired mandibular glands are formed by a cluster of glandular cells that release their secretion into a reservoir, and a main duct that connects the reservoir with the exterior (e.g., Billen & Al‐Khalifa, 2018; Billen & Schoeters, 1994). This duct opens on the mandalus, a membranous field on the (proximal) dorsal mandibular base.…”