Genus Lithochrysa Carpenter 1935, stat. res. Lithochrysa Carpenter, 1935: 262, 265, 269, 270; Adams 1957: 72; Tjeder 1966: 247; Adams 1967: 231 (as a synonym of Paleochrysa [sic]); Willmann 1993: 242; Archibald & Makarkin 2017: 399. Type species. Palaeochrysa wickhami Cockerell, 1914, by original designation. Emended diagnosis. May be distinguished from other genera of Nothochrysinae by a combination of the following. Forewing: (1) im elongate [Cimbrochrysa, Danochrysa, Asiachrysa, Okanaganochrysa, Leptochrysa: broadly pentagonal; Stephenbrooksia: very long, narrow]; (2) 2m-cu located in proximal part of im [Cimbrochrysa, Asiachrysa: approximately in middle of im; Kimachrysa, Pimachrysa, Pamochrysa, Hypochrysa, Asthenochrysa: proximad im]; (3) two gradate series in radial space [Okanaganochrysa, Triplochrysa: three; Dictyochrysa, Adamsochrysa: four or more]; (4) inner gradate series of radial space arranged in smooth line [Palaeochrysa, Tribochrysa: arranged in strongly broken line]. Hind wing: (5) MA fused with RP proximally for long distance [Archaeochrysa, Stephenbrooksia, Leptochrysa: separate]. Species included. Five species: Lithochrysa borealis Archibald & Makarkin, 2017 from the early Eocene of Driftwood Canyon, British Columbia, Canada; and L. wickhami, L. ferruginea (Cockerell, 1909), stat. res., L. concinnula (Cockerell, 1909), and L. meyeri sp. nov., all from the late Eocene of Colorado, Florissant, USA. Occurrence. Eocene (Ypresian to Priabonian) of North America. Remarks. Adams (1967) synonymized Lithochrysa and Palaeochrysa. Archibald & Makarkin (2017), however, examined new photographs of their type species, L. wickhami (Cockerell, 1914) and P. stricta Scudder, 1890, and found them clearly distinguished: in both the fore- and hind wings of Lithochrysa, Psm is poorly developed, strongly zigzagged, and the crossveins of the inner gradate series are arranged in a smooth line, but in Palaeochrysa, Psm is well developed, very slightly zigzagged (especially in the hind wing), and the crossveins of the inner gradate series are arranged in strongly broken line.

Published as part of Makarkin, Vladimir N., Antell, Gwen S. & Archibald, S. Bruce, 2022, A revision of Chrysopidae (Neuroptera) from the late Eocene Florissant Formation Colorado, with description of new species, pp. 301-345 in Zootaxa 5133 (3) on page 320, DOI: 10.11646/zootaxa.5133.3.1, http://zenodo.org/record/6522449