Mylothris jacksoni Sharpe, 1891

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 : 1573-1574

[ Mylothris jacksoni Sharpe, 1891 ]

Kielland 1990: 266 (3 figs). Larsen 1996: pl. 10 fig. 103i. D’ Abrera 1997: 109 (5 figs). SI: Figure 35a–d.

Occurs in submontane forest, apparently at slightly lower altitudes than the closely related M. sagala ( Larsen 1996) . Kielland (1990), however, gave 1900–2600 m for jacksoni and 700–2700 m for sagala (for Kenya, Larsen op. cit., indicates that sagala ascends to at least 3200 m). Adults of M. jacksoni (an abundantly distinct species in its life history: Colin Congdon, pers. comm.) are said to differ from those of M. sagala in the following respects: smaller; forewing upperside black border usually extending all around the wing, and forewing apex more acute and distal margin less rounded ( Kielland 1990, p.66). According to Larsen (1996, p.149) the dark markings of sagala are “less glossy and less deep than in M. jacksoni .” Examination of the genitalia of a single male M. jacksoni from northern Tanzania compared with four males of M. sagala from the West Usambara Mts suggests a slight difference in valve shape.

Kielland (1990) considered that two subspecies of jacksoni occur in northern Tanzania: nominate jacksoni from the Loliondo Hills ( Kenya border), and M. jacksoni neumanni Sharpe, 1896 , from Mt Longido and the Meto Hills. Ackery et al. (1995, p.220; perhaps following Rogers 1913, p.98) treated neumanni (type locality: region of Mt Kenya) as a synonym of nominate jacksoni (type locality: Kavirondo, eastern Lake Victoria, Kenya). Larsen (1996, p.149, pl. 10, fig. 102i), however, treated neumanni as the representative of M. sagala in Kenya’ s central highlands. Beyond Tanzania and Kenya, M. jacksoni is considered to occur in Nigeria, Equatorial Guinea (Bioko), Cameroon, Sudan, Ethiopia, DRC, Uganda, Rwanda and Burundi.

As Larsen (1996) noted, M. jacksoni and M. sagala – which were first distinguished at species level in the modern literature by Berger (1981) – are very variable and similar to each other. Larsen’ s treatment of neumanni, as noted above, suggests a possible problem in consistent separation. Liseki (2009) recorded both species from Mount Kilimanjaro. The forewing shape difference reported by Kielland (1990) seems difficult to apply consistently, and the extent of the forewing black border is variable in Kilimanjaro material. An additional character that appears to separate most sagala from jacksoni is the black spot at the tip of vein Rs on the hindwing underside, which is often enlarged in the former (SI: Figure 35f,h) but apparently not or only very slightly in the latter (SI: Figure 35b,d). All SDL’ s available material from Kilimanjaro has this spot more or less enlarged compared with the posterior marginal spots. We now consider that identification of SDL’ s Kilimanjaro material as M. jacksoni was an error due to unfamiliarity with the range of variation of M. sagala (see also below). However, in our view, the whole question of the identity and separation of these two species should be re-investigated.