Fossil butterflies, calibration points and the molecular clock (Lepidoptera: Papilionoidea) Author Jong, Rienk De text Zootaxa 2017 4270 1 1 63 journal article 32975 10.5281/zenodo.583183 6c479acc-8b18-4f0b-a6e5-85bcd6d7b6b7 1175-5326 583183 2D00AFF5-4FE2-4EC1-A328-C8670CFB8D6D crataegi . Aporia crataegi fossilis Kernbach, 1967 Pieridae . Germany , Hesse , Brandenburg , Willershausen; Plazencian, late Pliocene. Depository: GPUG (one specimen, 596-12[13589]). Published figures: Branscheid (1968: Figs 1 , 2 ) ; Branscheid (1969: Figs 2–5 ) ; Kernbach (1967: Fig. 12 ) . Numerous figures of the extant species in identification guides for European butterflies. Kernbach (1967) recorded one forewing and two hindwings from the clay of Willershausen as belonging to this extant Palaearctic species. The fossils are not described apart from the observation that the dark stripe between veins 1A+2A and CuA 2 in the hindwing is visible, and that the specimens were apparently larger in the Pliocene. In the accompanying photo of the hindwing the venation is rather similar to that of A. crataegi (Linnaeus) , except for Sc+R1 being much less strongly curved and the cell being distinctly shorter than in the recent species. Actually it is not clear what is typical about the Aporia hindwing venation, a similar venation also being found in the widespread recent genus Pieris and some other pierid genera. Also the stripe mentioned, which actually indicates the lost CuP, is not restricted to Aporia . Kernbach described the fossil as Aporia crataegi fossilis , rather prematurely since it is not even certain that the fossil is conspecific with the extant species. Apparently, the forewing, mentioned but not described by Kernbach (1967) was reported by Branscheid (1968) . It shows the pierid apomorphy of M1 branching off the common stem of R4 and R5 (R3 is considered being lost by various authors). Sc is reconstructed as ending on the costa just beyond the end of the cell, but this may be a misinterpretation, even in fresh Aporia specimens it may be difficult to see where exactly Sc ends on the costa, this vein at its distal end running close to R1. Since the wing is incomplete, the general shape cannot be made out and its identification as belonging to Aporia is not without doubt. Further wings from the same locality were described by Branscheid (1969) as most probably belonging to Aporia , although he was not sure about the (number of) species, since he found marked differences in size. For calibration purposes these fossils are hardly of interest. Not only are they rather young, but since they cannot reliably be identified even to the subfamily level, we could only use them as calibration point at the root of the Pieridae . (For a recent study of the phylogeny, see Wahlberg et al . 2014 , in which the late Pliocene appears far too recent for a divergence time.) In view of the extreme scarcity of butterfly fossils it is remarkable that so many specimens of a single genus or maybe even species have been found in the same locality. A possible explanation could be gregarious behavior on wet spots involving so called mud puddling that can be observed in many butterflies, including Aporia crataegi and many other Pieridae .