A groove on the mesopleuron, extending ventrally from a pit under the base of the forewings and, when complete, reaching the anteroventral margin of the metathorax.
written by: Goulet, H., and J. T. Huber. 1993. Hymenoptera of the World: An Identification Guide to Families. Research Branch, Agriculture Canada Publication 1894/E., Ottawa, ON 668 pp.