Introduction

Papilio dardanus (Brown), the Mocker Swallowtail, is widespread across sub-Saharan Africa, and about 13 geographical races have been described. This is a brief summary of the main races and morphs described for Papilio dardanus by Clarke & Sheppard (1959, 1960a, 1960b, 1962) and Ford (1936). The genetics of Papilio dardanus have been studied extensively by Sir Cyril Clarke and the late Philip Sheppard by forming hybrids between races. They found that the mimetic patterns were controlled by closely linked genes at a single locus and that they had a distinct order of dominance. The dominance is almost always complete, preventing intermediate forms from arising. There are, however, modifier genes on other chromosomes which perfect the mimicry. These are not present in the monomorphic races meriones and humbloti, and therefore hybrids between these races and mainland polymorphic races results in imperfect mimetic patterns (Clarke & Sheppard 1963) The morphs are represented by a single allele notation, and these are listed together with the description of each morph. Further information and colour photographs of some of the morphs are available on the Web site:

http://www.linacre.ox.ac.uk/research/dardanus_genetics/ (This site requires Internet Explorer Version 4 or above).

The Races

Race Humbloti

Race humbloti is restricted to the island of Grande Comore in the volcanic Comoro Island group. It is monomorphic, the females being tailed and resembling the males. Both sexes have quite heavy black markings, with a single, very thick black border to the hindwings and pure black tails. The females have much larger black 'epaulette' markings on the forewings than the males.

The butterflies live on the lower slopes of the volcanoes on Grande Comore, and are becoming increasingly scarce as the natural forest is turned to agriculture. This makes individuals particularly hard to get hold of, and it has also proved very hard to breed in this country.

There is much debate as to whether this race represents the primitive condition for the species (Trimen, 1869 and subsequently Poulton, 1924; Ford, 1936; Clarke & Sheppard, 1963; Turner, 1963; O'Donald & Barrett, 1973; Clarke et al., 1985), or whether the monomorphic state is derived (van Bemmelen, 1922; Bernardi, 1963; Vane-Wright & Smith, 1991). It is interesting that two of the butterflies which act as models for the species on the mainland, Danaus chrysippus and Amauris niavius, are plentiful on the island (pers. obs.). However, it may be that the adults are not under enough predation pressure to lead to mimicry, as the bird fauna is rather restricted and their main predators are likely to be other insects, and lizards.

Race Meriones

The race meriones is found on the island of Madagascar. It is rather similar to race humbloti, with monomorphic females resembling the males. The black markings are not as heavy as in humbloti, however, especially on the hindwings, where they differentiate into the thicker inner markings and the thin outer black line seen in the mainland races. The tails are also orange towards the tip as on the mainland. The females can be distinguished from the males by the presence of black 'epaulettes' on the forewings.

Individuals from this race are much easier to obtain from breeders than those from humbloti, and are therefore often used in inter-race crosses in order to determine whether or not modifiers are present in the monomorphic races associated with a mimetic ancestor for the race.

Race Dardanus

This is the most widespread race, its range extending from Sierra Leone to Angola in West Africa, and then east to Uganda and Lake Victoria in Tanzania, where it merges with race meseres.

The females are almost exclusively form hippocoon in the western part of its range, which closely resembles the form hippocoonides in the other races, mimicking Amauris niavius niavius. In the eastern part of its range, the females show increasing proportions of other morphs. In order of decreasing gene dominance, these are:

Race Cenea

This race is found in South Africa northwards to Delagoa Bay, and merges into race dardanus to the north east and race tibullus to the north west.

The females show six morphs. In order of descending gene dominance, the morphs are:

Race Tibullus

This race is found on the east African coast, from Delagoa Bay until somewhere around Mombasa, and on the island of Pemba off the coast of Tanzania. It merges with the form meseres to the west, form cenea to the south, and form polytrophus to the north.

The race is not documented as well as the others, but forms that are known to exist in it include:

On the island of Pemba, Cook et al. (1994) report that the forms cenea, salaami, leighi and natalica are not present, and it may be that these forms are only present where the race tibullus meets the adjoining races in which they are present.

Race Meseres

This race, found in Uganda, and Tanzania east of Lake Victoria, is also known as 'the transitional race', as it forms an intermediate between the race polytrophus to the north and east, race dardanus to the west, and race tibullus to the south (and a little east).

The females show six morphs, some of which are imperfect mimetic forms. Where this is the case, the prefix 'proto' has been used. In order of descending gene dominance, the morphs are:

Race Polytrophus

The race polytrophus is found in the mountains of Tanzania and Kenya east of Lake Victoria, meeting race meseres on the south west and race tibullus on the south east, and race antinorii to the north. It is an unusual race, as the mimicry of the females is often imperfect. This could be because its montane habitat in this region separates it from the model species.

The females show seven morphs. In descending order of genetic dominance, these are:

Race Ochracea

The race ochracea is found on the top of Mount Marsabit in northern Kenya. The females show two morphs only:

Race Flavicornis

Race flavicornis inhabits the top of Mount Kulal, also in Northern Kenya. It resembles race ochracea except that the tips of the antennae of both sexes are a striking red. The female forms are as in race ochracea.

Race Antinorii

This race inhabits the region north of Kenya, formerly Abyssinia, meeting race polytrophus to the south. It is an unusual race in that the females all possess tails like the males even though some of them are mimics of tailless species. The race is difficult to obtain, and has only been studied a little.

The females are all tailed, but show several different morphs:

The tails are controlled by a single major gene with modifiers, tailless (T) being semidominant to tailed (t). The locus is independent of wing pattern.

The morphs

Males

The males of Papilio dardanus are similar throughout the range of the species, although the extent of the black markings varies. In race humbloti, the black border to the hindwings is solid and the tails are also completely black. The females in races humbloti and meriones, and the yellow form in race antinorii resemble the males (gene H^y).

Trimeni

This morph resembles a tail-less male and is found in race tibullus on the east African coast.

Hippocoonides /Hippocoon

This widespread black and white morph mimics Amauris niavius. Hippocoon (which has more obvious rays on the hindwings than hippocoonides) is found in race dardanus in West Africa, and mimics Amauris niavius niavius, and the very similar hippocoonides mimics Amauris niavius dominicanus, and is found in races cenea, tibullus, meseres, polytrophus, ochracea, and flavicornis (where it has red tips to the antennae). It is genetically the bottom recessive (gene h).

Niavoides

This is the tailed form of hippocoonides, found in the northern race antinorii, where it roughly mimics Amauris niavius.

Natalica

This is a non-mimetic form which resembles hippocoonides except that the white areas are all buff. It is found in race cenea, and a tailed version exists in race antinorii. (gene H^na).

Cenea

This is a mimic of Amauris echeria echeria and Amauris albimaculata, and is found in races cenea, dardanus, polytrophus, and probably tibullus. A tailed form is found in race antinorii. (gene H^c).

Protocenea

This is an incomplete version of cenea, where fluorescent yellow pigment (Papiliochrome II) is present to some extent. It is found in races polytrophus and meseres.

Ochracea

This larger form of cenea, with more heavily spotted hindwings and all the whites replaced by buff, is a mimic of Amauris echeria septentrionalis, and is found in races ochracea and flavicornis (where it has red-tipped antennae). (gene H^o).

Trophonius (White lamborni)

This form mimics Danaus chrysippus, and is found in races cenea, polytrophus and tibullus, and as form trophonissa (with more obvious rays on the hindwings) in race dardanus. It is dominant to other forms (gene H^T).

Prototrophonius (Yellow Lamborni)

This is the incomplete mimetic form, in which the white areas on the forewings are replaced with fluorescent yellow. It is found in races polytrophus, tibullus and meseres.

Ruspinae

This is the tailed form of trophonius found in race antinorii.

Leighi

This is a non-mimetic form with light orange markings on the forewing and buff on the hindwing. It occurs in races cenea and meseres. (Gene H^L).

Planemoides

This morph rather resembles leighi, but with slightly more orange on the forewings, and the buff hindwing colour replaced with white. It is a mimic of Bematistes poggei, and is found in races dardanus and meseres. (Gene H^Pl).

Swynnertoni

This is an incompletely developed form of planemoides in which the bases of the hindwings are buff and the black bar on the forewings is just about complete. It is a heterozygote between planemoides and cenea (genotype H^PlH^c).

Niobe

This entirely bright orange morph mimics Bermatistes tellus. It occurs in race dardanus. (Gene H^Ni).

Salaami

This is a non-mimetic form very like niobe, but in which the orange on the forewings is slightly lighter than that on the hindwings. It is found in race cenea as a heterozygote of trophonius and leighi (genotype H^TH^L). A form called protosalaami, in which the black bar across the forewings is less distinct, is found in race polytrophus, and occasionally in meseres.

Dorippoides

This is a form of salaami in which the black bar across the forewings is completely absent, making the forewings almost entirely orange. It is formed in race polytrophus by interbreeding between race antinorii and form poultoni of race polytrophus.

Poultoni

This is also very similar to niobe, but the hindwings are slightly less rayed and the body is grey or fawn with black dots rather than orange. It has two forms - pale and bright - although the relationship between these forms in uncertain. It occurs in race polytrophus (genes H^pp or H^bp).

References

Bernardi, G. 1963. Quelques aspects zoogéographiques du mimétisme chez les Lépidpidoptères. Proceedings, 16^th International Congress of Zoology, Washington 4, 161-166.

Clarke, C.A. & Sheppard, P.M. 1959. The genetics of Papilio dardanus, Brown. I race cenea from South Africa. Genetics 44: 1347-1358.

Clarke, C.A. & Sheppard, P.M. 1960a. The genetics of Papilio dardanus, Brown. II races dardanus, polytrophus, meseres and tibullus. Genetics 45: 439-457.

Clarke, C.A. & Sheppard, P.M. 1960b. The genetics of Papilio dardanus, Brown. III race antinorii from Abyssinia and race meriones from Madagascar. Genetics 45: 683-698.

Clarke, C.A. & Sheppard, P.M. 1962. The genetics of Papilio dardanus, Brown. IV data on race ochracea, race flavicornis, and further information on races polytrophus and dardanus. Genetics 47: 909-920.

Clarke, C.A. & Sheppard, P.M. 1963. Interactions between major genes and polygenes in the determination of mimetic patterns of Papilio dardanus. Evolution 17, 404-413.

Cook, S.E., Vernon, J.G., Bateson, M., Guilford, T. 1994. Mate choice in the polymorphic African swallowtail butterfly, Papilio dardanus - male-like females may avoid sexual harassment. Animal Behaviour 47 (2), 389-397.

Ford, E.B. 1936. The genetics of Papilio dardanus Brown (Lep.). Transactions of the Royal Entomological Society of London 85, 435-466.

O'Donald, P. & Barrett, J.A. 1973. Evolution of dominance in polymorphic Batesian mimicry. Theoretical Population Biology 4, 173-192.

Poulton, E.B. 1924. Papilio dardanus. The most interesting butterfly in the world. Journal of the East African and Ugandan Natural History Society 20, 4-22.

Trimen, R. 1869. On some remarkable mimetic analogies among African butterflies. Transactions of the Linnean Society of London 26, 497-522.

Turner, J.R.G. 1963. Geographical variation and evolution in the males of the butterfly Papilio dardanus Brown (Lepidoptera: Papilionidae). Transactions of the Royal EntomologicalSociety of London115, 239-259.

Van Bemmelen, J.F. 1922. The wing-design of mimetic butterflies. Proceedings, Section of Sciences, Koninklijke Nederlandse Akademie Wetensschappen 23, 877-886.

Vane-Wright, R.I. & Smith, C.R. 1991. Phylogenetic relationships of three African swallowtail butterflies, Papilio dardanus, P. phorcas, and P. constantinus: a cladistic analysis (Lepidoptera: Papilionidae). Systematic Entomology 16: 275-291.