part of sclerite episternum preepisternum FBbt:00004555 fly_anatomy.ontology Anterior and major portion of the thoracic episternum. Accordingly to McAlpine (1981) the term mesothoracic preepisternum is used incorrectly (as by Snodgrass, 1935) and it should be referred to as katepisternum. In addition the mesothoracic katepisternum is frequently, but incorrectly called the sternopleuron (as in Steiner, 1976). Although in Diptera the mesosternum is greatly reduced and internalized, it is not fused with the katepisternum, and thus the latter should not be called sternopleuron. However, it seems that most publications still use the term sternopleuron (or sternopleurite) to refer to the katepisternum or preepisternum - https://orcid.org/0000-0001-5948-3092.