Histological evidence of a glandular tubercle at the abdominal tergite in three species of katydids (Orthoptera: Tettigoniidae)

Three species of Hyperophora Brunner von Wattenwyl have a tubercle on the second abdominal tergite with different external appearance among species. We predicted that the tubercles are a glandular structure for their morphology and anatomical position. In H. major Brunner von Wattenwyl and H. brasiliensis Brunner von Wattenwyl the tubercle is low and broad, whereas in H. minor Brunner von Wattenwyl it is high. In all species the tubercle does not have an external opening, but it has many chemosensory sensilla, evidenced by long setae with an internal cavity with a membrane-like content. The cuticular surface of the tubercle has many pores with ∼1-2 μm in diameter scattered among the sensilla. On the inner surface of the tubercular region occur epidermal gland cells, evidenced by a mass of large globular cells with an irregular and well-developed nucleus with predominance of decondensed chromatin and a large nucleolus. The cytoplasm of these cells is rich in small clear vacuoles, and has an end apparatus, a feature of epidermal gland cells of class III. Each gland cell has a conducting canal that opens into a cuticular pore. These results support the hypothesis that the tubercles are indeed of glandular nature.