Fossil butterflies, calibration points and the molecular clock (Lepidoptera: Papilionoidea) Jong, Rienk De Zootaxa 2017 4270 1 1 63 [151,258,873,899] Insecta Nymphalidae Lethe Animalia Lepidoptera 31 32 Arthropoda species montana    USA,  Montana, Canyon Ferry Reservoir; Rupelian, early Oligocene.  Depository: holotype, Museumof Rockies,  Montana State University, Bozeman(part and counterpart, MOR No. MV-152). Published figures: CoBabe et al. (2002, Fig. 4c), Miller et al. (2012: Figs 1–5. The fossil consists of a well preserved part and counterpart of a forewing. In their diagnosis the authors state that “… the unbranched forewing radial veins … indicate thet this fossil is … not a member of the Hesperioidea.” Rather, this should read “the branched forewing radial veins”, but the conclusion is correct. Moreover, the absence from the cubital spur and vein 3A eliminates Papilionidaefrom consideration. The authors also eliminate Pieridae, since M1 branches off the cell, although branching of M1 off R3 is widespread in Pieridaebut not universal. The remark that Riodinidaeor Lycaenidaecan be eliminated because the “… veins are not simple in that they do not arise from the base or from the radius or cubitus proper …”, is not clear to me. The authors arrive at the conclusion that the fossil belongs to the Nymphalidae, and since the forewing cell is closed, the subcostal vein is thickened at its base and there is a prominent ocellus in M1-M2, assignment to the Satyrinaeseems obvious. The only problem is, that the basal part of the wing with the swelling of the subcostal vein, as represented in their reconstruction in Fig. 5, is absent from the fossil ( Fig. 1) and from the interpretation of the fossil in Fig. 2. See also the discussion under  Lethe(?) corbierion the absence of a basal swelling in  Lethe. There is no convincing evidence for treating  Lethe montanadifferently than  Lethe(?) corbierias far as its use as calibration point concerns. They are approximately the same age. See also under Biogeographic considerations. 1503739255 [199,969,980,1005] United States of America Montana 31 32 1 Montana 1503739241 MOR Museum State University Rockies 31 32 1 Montana holotype