Thaites ruminiana

Jong, Rienk De, 2017, Fossil butterflies, calibration points and the molecular clock (Lepidoptera: Papilionoidea), Zootaxa 4270 (1), pp. 1-63 : 37

ruminiana . Thaites ruminiana Scudder, 1875

Figs. 14–16

Papilionidae : Parnassiinae : Parnassiini .

France, Bouches-du-Rhône, Aix-en-Provence; late Oligocene–early Miocene.

Depository: PMUZ (holotype).

Published figures: Demoulin (1975: Fig. 2 ); Leestmans (1983: Figs 1–4 ); Murata (1998: Figs 12 –15); Scudder (1875: Pl. III Figs 1 , 3 , 6–10).

This specimen is only partly preserved; most of the venation and much of the pattern is discernible. Although Scudder usually is very accurate in his figures and descriptions, his figure of the left underside of the fossil (pl. III Fig. 9) must be incorrect in that it shows two subcostal veins in the forewing. In his reconstruction of the venation (Pl. III Fig. 1 ) the normal, single subcostal vein is depicted. The radial formula is: 1, 2+3, 4+5, with R2 and R3 separate close to the apex. Posterior margin of cell quadrifid, an apomorphy of Papilionidae . A cubital spur, another apomorphy of Papilioninae , is not apparent. Hindwing with single anal vein, an apomorphy of Papilionidae . Starting from the assumption that the radial formula 1, 2, 3+(4+5) belongs to the groundplan of the Papilionidae , the fossil cannot belong to the ancestry of any taxon in this family where the plesiomorphic condition has been retained. With slight variations, this is the case for all papilionid genera except for Parnassius and Hypermnestra . Therefore, only these genera can be considered as close relatives of Thaites ruminiana . Parnassius and Hypermnestra are thought to be sister groups by Hancock (1983), Omoto et al. (2004) and Nazari et al. (2007), the ancestor of which has lost R3 by fusion with R2; in some Parnassius species a further fusion seems to take place in a terminal anastomosis of R1 and R2. Thaites fits in quite well here, as sister group of both. According to Hancock (1983) Thaites is an offshoot of the ancestral line of Parnassiini , which is unlikely, as is his opinion that Archon belongs here, although it has retained the plesiomorphic radial vein arrangement. In the Parnassiini sensu Nazari et al. (2007) the tribe consists of Parnassius and Hypermnestra only, with which the fossil shares the apomorphic condition of the radial vein venation. Consequently, the fossil should be placed as sistergroup of Parnassiini sensu Nazari et al. (2007). However, Nazari et al. (2007) had included the fossil in their phylogenetic analysis of the morphology and molecular characters of extant species (see also under Doritites bosniaskii and Praepapilio colorado ). In the analysis it appeared as an offshoot of the Parnassiini lineage, before it split into Parnassius and Hypermnestra . For the calibration of the clock such a switch of a taxonomic assignment may be of little consequence, since it concerns a sister group, but yet it is preferable to have relationships explicitly stated. New information, such as more or other molecular data or additional taxa, may prompt another rearrangement of genera and then the date of the calibration point should be clear.

For the sake of historical completeness but without impact on the discussion above, the following information is provided. Principally because of similarities in wing pattern apparently based on symplesiomorphies, Scudder (1875) considered the fossil a close relative of Thais rumina (Linnaeus) , now allocated in the genus Zerynthia , hence the name. Stichel (1907) and Verity (1947) assigned the fossil to the tribe Zerynthiini , without much comment. Bricoux (1975) followed Verity (1952) in considering Thaites ruminiana as the ancestor of Zerynthia rumina , what is most unlikely because of the venation issues as explained above. Demoulin (1975) is of the opinion (based on venation) that the fossil is a precursor of Parnassius ; he does not mention Hypermnestra .

With two other papilionid fossils, this fossil was used for calibration by Condamine et al. (2012), see discussion under Praepapilio colorado .

Figures

FIGURE 1. Localities of fossil butterflies plotted ion a modern map. See Table 1 for further, complementary information.

FIGURE 2. Apomorphies, their placement on a tree, and the assignment of calibration points. See text for explanation.

FIGURES 3 – 4. Wing venation of (A) Pareronia Bingham, 1907 (Pieridae), and (B) Hasora Moore, 1881 (Hesperiidae). See text for explanation.

FIGURES 11 – 13. Ƒanessa pluto Heer, 1849. Figures copied from (1875), Plate II, figures 1, 17 and 7, respectively. (A), copied by Scudder from original description by Heer; (B) and (C), figures sent to Scudder by Mr. Brunner de Wattenwyl, made after the same object. Note differences in wing shape and other details. Figs 14 – 16. Thaites ruminiana Scudder, 1875. Figures copied from Scudder (1875), Plate III, figures 9, 1 and 3, respectively. (A), underside of fossil; (B), reconstruction of venation; (C), reconstruction of markings. In (A) two separate subcostal veins have been drawn in the forewing, an impossible configuration in Lepidoptera, and apparently a mistake, corrected in (B) and (C). Fig. 17. Cyllo sepulta Boisduval, 1841, wing venation after Scudder (1875). Fig. 18. Butterfly fossil recorded by Wangrin (1939), but shown to be a fraud by Ansorge (2015). Photo kindly provided by J. Ansorge, Horst, Germany (see text for explanation).