sternite
noun
ster·nite ˈstər-ˌnīt 
: the ventral part or shield of a somite of an arthropod
especially : the chitinous plate that forms the ventral surface of an abdominal or occasionally a thoracic segment of an insect
Word History
Etymology
International Scientific Vocabulary, from Greek sternon chest
First Known Use
1868, in the meaning defined above