Nepheronia thalassina (Boisduval, 1836)

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 : 1560-1561

Nepheronia thalassina (Boisduval, 1836)

Kielland 1990: 266 (1 fig). Larsen 1996: pl. 5, figs 40 i,ii. d’ Abrera 1997: 71 (5 figs). SI: Figure 20e–j.

Forewing length: male 31–36 mm (mean (n = 5) 34.2 mm, SD = 1.564); female 32– 38 mm (mean (n = 9) 35.47 mm, SD = 1.517).

Records. From Mpanda to Ugandan border, Northern Highlands, Pare Mts, Usambara Mts, Uluguru Mts, Turiani, Nguu forests, Image Mt, Mwanihana forest, Ukaguru Mts, Kiono forest, Pugu hills, Dendene, Masagati and the Rondo plateau, from sea level up to 1700 m ( Kielland 1990, p.54). On Kilimanjaro it evidently does not penetrate into the forest reserve area, being confined to the lower slopes (records in BMNH from Moshi and New Moshi, and from Kilimanjaro at 4500–5000 ft). Outside Tanzania, found in forest and dense woodland across central Africa ( Ackery et al. 1995, p.181). There is debate as to whether this species is polytypic or not – here we follow Berger (1981, p.80) and Kielland (1990) in regarding it as monotypic (if divided into subspecies, then the Kilimanjaro population belongs to N. t. sinalata (Suffert, 1904) – treated by Berger 1981, as a form).

There are two forms of female N. thalassina in Tanzania: white (typical), and piebald (f. “sinalata”). Typical females tend to have some pinkish-grey at the forewing base, and yellowish at the base of the hindwing. Form “sinalata” may or may not have the colour at the base of the forewing; the hindwing is all yellow. Some females of both forms have a flush of yellow at the base of the forewing beneath. Elsewhere a few other female forms occur, such as “verulanus” in Cameroon. In life, males are notable for their pale blue ground colour, and both sexes have a nacreous sheen to the underside, which aids separation of female forms of this species from those of N. argia ( Larsen 1996, p.126)