Anatomical and histological descriptions of the alimentary system, salivary gland, and Malpighian tubules of Legnotus limbosus, the bordered shieldbug (Geoffroy, 1785) (Heteroptera: Cydnidae)-light and electron microscopic studies.

Abstract

We reported the histological and anatomical analyses of Legnotus limbosus's alimentary and excretory system using stereomicroscope, light and electron microscopy. As a result of the obtained data, the digestive tract of L. limbosus has three main parts: fore, mid, and hindgut. The salivary gland and gastric caeca are structures that assist digestion. The salivary gland is a pair consisting of the principal and accessory salivary glands. The foregut has the pharynx and esophagus. The pharynx structure is located immediately after the mouth and continues with the esophagus as a thin, long canal. The esophagus connects to the ventriculus 1 (V1). The midgut consists of three parts: V1, V2, and V3. The V1 and V2 have a single layer of cylindrical epithelium. However, the proximal and distal parts of V3 have cylindrical epithelium, while the lateral part exhibits a cuboidal form. The ileum and rectum make up the hindgut. The first has a cylindrical epithelium; the second has a squamous epithelium. The two pairs of Malpighian tubules, which are attached to the midgut-hindgut junction, are responsible for excretion and osmoregulation. Crystals with a deltoid shape are seen in the lumen of the Malpighian tubule and the rectum. This study is the first on the digestive and excretory system morphology of the Cydnidae family and will make significant contributions to studies on this subject in the Heteroptera, including this family.