<p><strong>New species of <em>Archisargus </em>from the Middle Jurassic Daohugou of Northeastern China (Diptera: Brachycera: Archisargidae)</strong></p>

Abstract

Archisargidae, an extinct family of the suborder Brachycera, are traditionally attributed to the infraorder Stratiomyomorpha (Oberprieler & Yeates, 2012). The type genus, Archisargus Rohdendorf, 1938, is a small group including only four species from two well-known localities, the Karatau Formation of Kazakhstan and the Jiulongshan Formation of China. Rohdendorf (1938) erected the genus based on the species Archisargus pulcher from the Karatau Formation of Kazakhstan, and assigned it to Stratiomyidae. Hennig (1954) questioned Rohdendorf’s assignment and pointed out that the characters of the Stratiomyidae were absent, but he didn’t propose an appropriate placement for this genus. Rohdendorf (1962) reconsidered the systematic position of the genus and established the new family Archisargidae based on the genus. In fact, the description of the Archisargus was not informative due to the incomplete preservation of the type specimen (only Sc and R were mentioned) (Rohdendorf, 1938). Mostovski (1997) re-described the type specimen of Archisargus pulcher, clarified the status of the genus, and described a second species, Archisargus maximus, which was also from Karatau, Kazakhstan. A decade later, Zhang et al. (2007) described two older species from the Middle Jurassic of Daohugou, China. The Daohugou locality is well-known for its diverse fossil insects, representing an important diversification center of insects during the Mesozoic Era (Ren et al., 2009; Wang et al., 2010, 2012; Gao et al., 2012; Gu et al., 2012; Meng et al., 2017; Ren et al., 2019). Herein, we describe a new species, Archisargus aequinervus sp. nov., from this locality. Additionally, a key to species of the genus is provided.