- Fossil butterflies, calibration points and the molecular clock (Lepidoptera: Papilionoidea)
- Prodryas persephone
persephone . Prodryas persephoneScudder, 1878
USA , Colorado , Teller County , Florissant; late Priabonian, late Eocene.
Depository: MCZH (holotype, no. 394).
Published figure: Emmel et al . (1992 : Fig. 1 /5, and at back of color plate III); Murata (1998: Figs 46–49) ; Scudder (1889: Pl. LII Figs. 1 –10) .
After the original decription ( Scudder 1878 ), the author described and figured this specimen extensively in 1889. A well preserved, medium-sized (length of forewing 24.5 mm ) and strongly built insect. The forewing, radial formula is 1, 2+(3+(4+5)), udc originates between R1 and R2 (slightly closer to R1); M1 and M2 originate close together near upper cell corner; cell open. In the hindwing Rs originates far basad; cell open; tail at M3, from here to tornus termen crenulate. The open cell in forewing and hindwing is an apomorphy found in many Nymphalinae and separately derived in some members of other nymphalid subfamilies. Emmel et al . (1992) assigned the fossil to this subfamily, but in the absence of additional apomorphies, we cannot be sure about the subfamily.
On the basis of overall similarity with extant genera, earlier authors have discussed its identification. According to Forbes (1932) and Brown (1978) the fossil is very close to the modern genus Hypanartia . This genus occurs, with eight species, in Central and South America ( DeVries 1987 ). This author thought this fossil was a close relative of the African genus Antanartia (see also Brown & Heineman 1972 ), but Wahlberg et al . (2009) place Hypanartia as sister to Vanessa , and Antanartia as sister to Aglais , Polygonia , Nymphalis and Kaniska . One species of Hypanartia may occasionally stray into the southern USA ( Scott 1986 ). Wahlberg et al . (2005a , 2009 ) and Heikkilä et al . (2011) followed Forbes and Brown in additionn to personal information from Willmot that the fossil is very close to Hypanartia and used the fossil as calibration point for the split between Vanessa and Hypanartia . This is an undesirable situation, since any information on characters, let alone apomorphies, is missing. Brown's (1978: 8) remark: "Careful examination of Scudder's type has led to the realization that it is little different, if any, from the modern genus Hypanartia ." sounds reassuring, but does not convey much information on the presence of apomorphic characters. It is reminiscent of the case of Vanessa amerindica (see above), which is considered a member of the genus Vanessa because of the presence of a produced forewing apex with a lobe at M1- M2, a character that does not seem to be restricted to this genus.
It must be remarked that the double spot between M2 and M3, clearly indicated in Scudder’s figures, is unlike any feature found in recent butterflies. If there is a spot in this space, it is always single, and if there is a spot between M1 and M2, it is close to the spot between M2 and M3 and not placed further basad. It seems possible that the division of the spot between M2 and M 3 in the fossil is an artefact.
- Prodryas persephone