Robuta

https://biostor.org/reference/232292 A new species of Heteranthidium from California (Hymenoptera : Megachilidae ) Published in Contributions in Science, in 1966, in volume 97, pages 1-8 a new from california species hymenoptera megachilidae https://journals.ku.edu/melittology/article/view/11760?articlesBySameAuthorPage=4 On the classification of North American Chelostoma (Hymenoptera: Megachilidae) | Journal of... on the north american classification chelostoma hymenoptera