The digestive system of the Arumatia dubia (Phasmatodea: Diapheromeridae): a morpho-histology characterization

Stick insects are herbivorous animals found in tropical, subtropical or temperate regions worldwide. Their digestive system is typically tubular, divided into regions with subregions that can vary among species. Arumatia dubia (Phasmatodea: Diapheromeridae) is a species that has undergone several taxonomic changes based on recent studies of external morphology, but morpho-histological analyses of internal organs, such as the digestive system, can contribute with identification to these and other Phasmatodea species. This study aimed to describe the digestive system of third instar A. dubia nymphs, using histochemical techniques and scanning electron microscopy. The digestive system of A. dubia consists of three regions and their subregions: foregut (esophagus and crop), midgut (anterior and posterior), and hindgut (ileum and rectum). The foregut has a simple epithelium covered by the tunica intima, and externally, surrounded by muscle fibers. The midgut features columnar cells with a brush border and regenerative cells. Malpighian tubules originate in the ileum (hindgut) and have an excretory function. This study provides detailed morpho-histological data on third instar A. dubia gut, contributing important information about the morphology and histology of the digestive system of this species.