Dixeia orbona vidua (Butler, 1900)

Liseki, Steven D. & Vane-Wright, Richard I., 2014, Butterflies (Lepidoptera: Papilionoidea) of Mount Kilimanjaro: family Pieridae, subfamily Pierinae, Journal of Natural History 48 (25 - 26), pp. 1543-1583 : 1571

Dixeia orbona vidua (Butler, 1900)

Larsen 1996: pl. 9, figs 90 i,ii. d’ Abrera 1997: 105 (4 figs). SI: Figure 32a–h.

Forewing length: male 21–30.5 mm (mean (n = 6) 26.58 mm, SD = 3.150); female 21– 28 mm (mean (n = 7) 24.11 mm, SD = 1.953).

Records. Bukoba, Rukwa basin and Northern Highlands; found in open woodland and open montane forest, to 2000 m ( Kielland 1990, p.64). Cordeiro (1990) recorded this taxon from Lake Manyara National Park. Although Kielland did not give specific records for Kilimanjaro, and the butterfly was not encountered in the forest zone by Liseki (2009), it is included here as a member of the lower slopes fauna based on a female in BMNH from W. Kilimanjaro, 4500–5000 ft, collected in 1937 by B. Cooper, and a pair from Kilimanjaro collected by F.J. Jackson. In addition, OUMNH has a male from Taveta, and a female from Kilimanjaro, both ex Rogers. Beyond Tanzania this subspecies occurs in Sudan, Ethiopia, DRC (east Kivu), Uganda and Kenya. More widely, the species occurs across much of central Africa, from Senegal to Ethiopia and south to Zambia ( Ackery et al. 1995, p.212).

Males are white, with or without a black forewing apex and margin; females are mostly fairly similar, more or less lightly maculated, and generally with a greyishyellow cast. Larsen (1996, p.143) states that “The smaller D. orbona is very similar [to D. pigea ] and the two may be impossible to tell apart”. Talbot (1943b, p.106) originally indicated that female pigea (“fw. 26–32 mm ”) were larger than female orbona (“fore-wing 21–25 mm ”). However, our limited data indicate a substantial overlap in size. Form “nigricans” (SI: Figure 32g,h), first described from Taveta by Aurivillius (1910c: 47), is dusky and this, together with the existence of a number of rare morphs (e.g. the bright orange form noted by Larsen 1996, p.143), indicates that the female of this species is polymorphic as well as variable, including at least two yellow morphs. Talbot (1943b, p.106) gave a key to 11 named female forms for this species.