Priacma Leconte, 1874

Tan, Jingjing, Ren, Dong & Shih, Chungkun, 2006, First record of fossil Priacma (Coleoptera: Archostemata: Cupedidae) from the Jehol Biota of western Liaoning, China, Zootaxa 1326, pp. 55-68 : 56-57

Genus Priacma Leconte, 1874

Type species. Cupes serrata Leconte, 1861 , by monotypy; Recent.

Included species. In addition to the new species described below, six species were known before. P. serrata Leconte, 1861 is the only one extant species from North America. Others are all fossil species from the lower Cretaceous: P. corrupta Ponomarenko, 1986 from West Mongolia, P. longicapitis Ponomarenko, 1997 and P. oculata Ponomarenko, 1997 from South Mongolia, P. s t r i a t a Ponomarenko, 2000 from East Transbaikalia, and P. s a n z i i Sorinao and Delcls, 2006 from Spain.

Diagnosis (based on the original description of the type species and on the study of four new species). Head with two pairs of sub­acute tubercles; antennae filiform, somewhat moniliform, less than half as long as entire insect; mandibles strongly extending, bidentate or tridentate at apex; gula wide, somewhat rectangular, widening posteriorly; genae separated for entire length by gula. Pronotum nearly rectangular, angles sharp; prosternum without tarsal groove; prosternal process only shallowly extending behind coxae. Elytra with nine or ten almost complete rows of punctures, dorsal surface convex, longitudinal ridges bearing small tubercles.

Remarks. The newly described cupedids from the Yixian Formation belong to the tribe Priacmini of the family Cupedidae because of antennae less than half as long as entire insect, inter­antennal distance much greater than diameter of eyes and prosternal process only shallowly extending behind coxae. Priacmini includes two extinct genera ( Ponomarenko 1969): Cupidium Ponomarenko, 1968 (from the Late Jurassic of Kazakhastan), Priacmopsis Ponomarenko, 1966 (from the Early Cretaceous of Mongolia and Siberia), and one extant genus Priacma .

The new fossils can be placed in Priacma based on the pedicel obviously shorter than third antennomere and anterior angles of pronotum sharp and extending.