Charaxes saturnus

Where C. saturnus is sympatric with Charaxes epijasius[stat.rev.2005],[4] over an extensive zone of overlap, the two species hybridize regularly, producing highly variable transitional specimens(C. saturnus x C. epijasius). The distribution range of hybrid forms extends from Ethiopia to Western Kenya & Northern Tanzania.[4] The variable hybrid forms have historically been named as harrisoni,[7] saturnalis,[8] and pagenstecheri[3][4] Observation of hybrid forms in Tanzania, as an example, beyond the recognised range of C. epijasius, strongly indicates that the hybrid forms may exist as fertile hybrids, at a lower prevalence[9] than the relatively more stable phenotype of C. saturnus. More detailed phylogenetic research and breeding studies are required to elucidate further the relationships between the two species and their intermediate hybrid phenotypes, and the degree of fertility exhibited amongst their highly variable intermediate forms.

• C. saturnus saturnus, Butler, 1866.[2] (TL="Interior of Africa")

In the western areas of its range, it is more variable which has led to some earlier authors to suggest a western subspecies (e.g. Poulton, 1926, TL= N. Angola[3]). Recent detailed re-evaluation found no western locality-depended areas with consistent population phenotypes which could merit infraspecific definition, including in Angola.[10]

The Charaxini taxa harrisoni, saturnalis, and pagenstecheri are now thought to be at least partially fertile hybrid variable phenotypes of (C. saturnus x C. epijasius). This would suggest that evolutionary divergence to fully stable species separation between C. epijasius and C. saturnus is not complete. Further phylogenetic research is required to clarify the current position further.

Historical attempts to assemble a cluster of presumably related species into a "Charaxes jasius Group" have not been wholly convincing. More recent taxonomic revision,[4] corroborated by phylogenetic research, allow a more rational grouping congruent with cladistic relationships. Within a well-populated clade of 27 related species sharing a common ancestor approximately 16 mya during the Miocene,[11] 26 are now considered together as The jasius Group.[4] One of the two lineages forms a robust clade of seven species sharing a common ancestor approximately 2-3 mya, i.e. during the Pliocene,[11] and are considered as the jasius subgroup.[4]

The jasius Group (26 Species)

Clade 1: jasius subgroup (7 species):[4]

• Charaxes jasius
• Charaxes epijasius [stat.rev.2005][4]
• Charaxes legeri
• Charaxes saturnus [stat.rev.2005][4]
• Charaxes pelias
• Charaxes castor
• Charaxes hansali

Clade 2: contains the well-populated three additional subgroups (19 species) of the jasius Group, called the brutus, pollux, and eudoxus subgroups.[4] Further exploration of the phylogenetic relationships amongst existing Charaxes taxa is required to improve clarity.

The early stages from egg to pupa are described in detail by Dr. V. G. L. van Someren & Rev. K. St. A. Rogers[15]

After hatching, the larva eats the remaining eggshell, rests for 12hrs, and commences nocturnal habit of devouring leaves on the host plant, non-selective as to age and size of leaf. The larva spins a silken refuge on a selected leaf to rest during the day. The larva is initially yellowish-olive with a blackish-brown head bearing short tubercles. The body is finely papillated, and two pale tails arise from the anal segment. After the first moult, the larva is green, with a green face.

Larvae polyphagous on a wide range of hosts including Brachystegia , Hibiscus, Croton sp., Afzelia quanzensis, Bauhinia galpinii, Burkea africana, Schotia brachypetala, the red spike-thorn shrub and tree Gymnosporia senegalensis, Colophospermum mopane, Xanthocerces zambesiaca, Julbernardia globiflora, Xeroderris stuhlmannii, Guibourtia conjugata, Catha edulis.[14]