Morphology of the Novel Basimandibular Gland in the Ant Genus Strumigenys (Hymenoptera, Formicidae)

In 1999, Barry Bolton postulated the presence of a basimandibular gland in the mandibles in all species of the ant genus Strumigenys, solely based on scanning microscopy observations. We now confirm the presence of this putative gland in the proximal outer part of the mandibles of 22 investigated species by histological and ultrastructural examination, including 10 short- and 12 long-mandibulate species. All species have a basimandibular gland, that is formed by 15–25 µm thick epithelial cells and belongs to class-1 following the standard classification of insect exocrine glands. We consider it a novel gland because of its peculiar bowl-shape and special arrangement of the microvilli that are confined to large vacuolar spaces instead of reaching the cuticle. The gland is most pronounced in S. mutica, particularly in the queen. In addition to this gland, we also found scattered class-3 intramandibular gland cells in the mandibles. Queens of S. mutica are peculiar in having a cluster of these cells in the distal tip of their mandibles. As this species is a social parasite, further research is required to determine whether the development of these mandibular glands is related to its parasitic lifestyle.

Description of the Intramandibular Gland II in Polybia emaciata Lucas (Hymenoptera, Vespidae)

The intramandibular gland II in Polybia emaciata Lucas is described. This species is among the few that uses mud for nest construction, and their nests persist for a long time following abandonment. The intramandibular gland II has been found in single representatives of the genera Mischocyttarus, Apoica and Leipomeles, and this record is the second for the genus Polybia. Despite expectations derived from the nest characteristics of the species, gland dimensions such as cell diameter were well within the range observed for other species, with the cell number even comparatively small. Gland function remains to be investigated.