The second North American fossil horntail wood-wasp (Hymenoptera: Siricidae) from the early Eocene Green River Formation Author Archibald, S. Bruce Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V 5 A 1 S 6, Canada; and Museum of Comparative Zoology, 26 Oxford Street, Cambridge, Massachusetts, 02138, United States of America; and Royal British Columbia Museum, 65 Belleville Street, Victoria, British Columbia, V 8 W 9 W 2, Canada. Author Aase, Arvid Fossil Butte National Monument, 864 Chicken Creek Road, Kemmerer, WY 83101, Wyoming, USA. Author Nel, André Institut de Systématique, Évolution, Biodiversité (ISYEB) Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, CP 50, 57 rue Cuvier 75005 Paris, France. text Zootaxa 2021 2021-07-13 4999 4 325 334 journal article 5336 10.11646/zootaxa.4999.4.2 6e1e8064-37e6-486f-b4fa-de0170edfb5d 1175-5326 5119186 4DD55A91-8739-4AC5-9208-36B7DF7AF22F Eoteredon lacoi sp. nov. ( Figs 3 , 4 ) Material. Holotype FOBU13582 (part and counterpart of a nearly complete female) ( Fig. 3 ). Housed in the collections of Fossil Butte National Monument , Kemmerer , Wyoming . Etymology. The specific epithet is formed from the surname of Greg Laco, who donated the holotype to Fossil Butte National Monument, recognizing his contribution. Diagnosis . As for the genus. Type locality and horizon . The type and only specimen was found in the 18-inch Layer of the Fossil Butte Member of the Green River Formation in Fossil Basin , approximately six meters below the K-spar Tuff dated at 51.98 ± 0.35 Ma. The Smith Hollow type locality is 11 miles west of downtown Kemmerer , Wyoming , USA . Description . Female, preserved in ventral aspect, except head in frontal aspect. Head poorly preserved, 4.5 mm long, 3.5 mm wide, with compound eyes, mandibles poorly visible; ocelli, antenna, antennal sockets not discernible; thorax 8.7 mm long, 5.5 mm wide; only parts of metathoracic legs preserved, poorly: femur 2.2 mm long and 1.0 mm wide, 3.5 as broad as metatibia; metatibia ca. 3.8 mm long as preserved, 0.3 mm wide; fragments of metabasitarsomere possibly present. Forewing 17.5 mm long, 5.0 mm wide, with apex poorly preserved; 2r–m present, joins cell 2M; cell 1Rs2 clearly longer than wide; cell 1R1 rather broad, only 2.8 times as long as broad; cell 2R1 about 0.7 times as long as cell 3R1; 2r-rs joins stigma in its distal half; stigma gradually attenuated evenly distal to junction with 2r-rs; Cu1 absent; 1cu–a joining Cu midway between 1m –cu, M; Sc faint, present in basal third of wing; 2A extending along posterior edge of wing about 0.5 times cell 1A length; 3A possibly distorted (see text). Hind wing ca. 11.3 mm long; anal cell presumed open (see below); hamuli not discernible; 1r–m clearly shorter than M; 1r–m at basal third of cell 1M; M markedly curved; abdomen 16.3 mm long, 7.0 mm wide, tergites not discernible (preserved in ventral aspect); distinct but incomplete ovipositor, preserved portion 8.8 mm long, extending 2.2 mm from abdomen; annuli not discernible.