M. V. Mokrousov
On the synonymy of two digger wasps (Hymenoptera: Sphecidae, Crabronidae) from the Oriental and Palaearctic regions.
Number: 328, Pages: 35 - 36
New synonymy is proposed for Chalybion (Hemichalybion) sumatranum (Kohl, 1884) = Sceliphron clypeatum Pham, 2016, syn. n. and for Holotachysphex mochii (de Beaumont, 1947) = Holotachysphex prosopigastroides (Gussakovskij, 1952), syn. n.