A novel intramandibular gland in the ant Brachyponera sennaarensis

Abstract

One of the diagnostic characters of the ponerine ant genus Brachyponera is the presence of a mandibular pit near the insertion of the mandible. This paper describes the morphology and ultrastructure of a novel intramandibular gland in B. sennaarensis, that is associated with this pit. The gland appears as a conspicuous epithelium that lines the invaginated cuticle of the pit, and that extends distally into the upper and lower outer wall of the mandible. This novel ‘mandibular pit gland’ occurs in both workers and queens, but is absent in males. At the ultrastructural level, the cytoplasm of the cylindrical secretory cells is dominated by a well-developed smooth endoplasmic reticulum. Apical microvilli and clear transcuticular channels allow secretion to reach the mandibular surface. Although the function of this novel gland is not yet known, the cytoplasmic organization is in line with the production of a pheromonal secretion.