1♀ (Figs 1–3), Saudi Arabia: Riyadh, Al Amariah, Majra [Mazra’ah], Al-Gasim [farm], 2.viii.2011 [2 August 2011], I. Naser; 1♂ (Figs 4–6), Saudi Arabia: Riyadh, Honeybee Queen Breeding Station, Ministry of Agriculture, Namar, 9.x.2012 [9 October 2012], M.A. Hannan. The female is deposited in the King Saud University Museum of Arthropods, Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Kingdom of Saudi Arabia, while the male is deposited in the Division of Entomology, Snow Entomological Collections, University of Kansas Natural History Museum, Lawrence, Kansas, USA.

The new material does not differ in any significant manner from the diagnosis and description of the species as provided by Engel (2009). Unfortunately, the sole Saudi male is not preserved in the best condition, with some distortion of the antennae and much of the body matted resulting from the mode of collection and subsequent preparation (Figs 4–6). Nonetheless, it was suitable for dissection and the terminalia are presented here for the first time (Figs 7–10) and for comparison with those structures depicted for other species (e.g., Engel 2006, 2007, 2010; Straka and Engel 2012; Engel and Packer 2013).

Presently there are only three species of Chiasmognathus recorded from the Arabian Peninsula: Chiasmognathus aurantiacus Engel from the United Arab Emirates, Chiasmognathus himyarensis Engel from southwestern Yemen, and Chiasmognathus nearchus from Oman, the United Arab Emirates, and now central Saudi Arabia. A key to these species was provided by Engel (2009). The new records presented herein push the distribution of Chiasmognathus nearchus and the genus as a whole westerly into the central desert region of Saudi Arabia. This is not surprising given the broader distribution of the group as well as that of its hosts. Species of Nomioides Schenck and Ceylalictus Strand are both present throughout the peninsula (Pesenko and Pauly 2009) and there is therefore every reason to suspect that with continued intensive sampling additional records will be forthcoming. Moreover, given that there are at least 20 species of Nomioidini present in the region it is possible that new species of Chiasmognathus may be recovered. Given the more varied habitats to the southwest, it is possible that endemic species of the genus may be found in the mountainous regions such as the Asir and Sarawat ranges south from Makkah (Mecca) and Taif, or in the low elevation plain of the Tihamah bordering the Red Sea. Unfortunately, at present none of the Saudi specimens have been collected in a context from which a positive host association can be made. Given that aggregations of Nomioides rotundiceps are in the area, as well as other nomioidine species, it is possible that this is the host of the Saudi populations of Chiasmognathus nearchus just as is the case for those in the United Arab Emirates (Engel 2009).