The genus Ampittia and Africa

The type species of the genus Ampittia Moore is from the Oriental Region: Hesperia maro Fabricius by original designation [currently considered a junior synonym of Ampittia dioscorides Fabricius]. Aurivillius (1925) described a new Tanzanian species as Ampittia parva, noting the strong upperside similarity with A. maro. However, he also included several Malagasy species in Ampittia —where they do not belong—which were removed by Evans (1937) to his new, very different, endemic Malagasy genera Hovala (Heteropterinae) and Fulda (Hesperiinae). Evans maintained A. parva as one of only two Afrotropical species in Ampittia, adding A. capenas (Hewitson), till then usually placed in the genus Kedestes Watson.

Ampittia is one of ten genera in the well-characterized tribe Aeromachini Tutt, often referred to as the Halpe - group, a sister-group to all other Hesperiinae and almost exclusively found in the forest zone of the Oriental Region (Warren et al. 2008; 2009). Forest genera of Afrotropical and Oriental Hesperiidae are not usually shared and we wondered whether African species were genuinely congeneric with the Oriental—or for that matter with each other. Both African species have a strong superficial resemblance to one or more Oriental members of the genus Ampittia as shown in figure 1. The similarities are striking but not necessarily significant since the colour patterns are not that special in their layout.

However, the Aeromachini all have rather special male genitalia. There are two rounded uncus lobes that are completely fused with the tegumen so that it cannot be moved independently. The uncus/tegumen structure has what might be described as a matt “sandpapery” texture, whereas in most Hesperiinae it is completely smooth and glossy. The two lateral branches constituting the gnathos have the same texture and density. The dorsal “roof” of the structure is broad, flat, and inflexible, impossible to mount for a lateral view under the microscope. The African species match these characters (figure 2A).

Members of the Aeromachini having male forewing brands nearly always have a most unusual feature in the hindwing venation—the “tuning-fork” (Watson 1893) or “hairpin” (Evans 1937). This refers to the characteristic way in which the veins 5 and 6 originate by being U-shaped at the base (shown in red in figure 2B). It is absent in those species that lack a brand. The male of A. capenas, which has the irregular “ Halpe -brand” (varying from almost fully developed to absent) also has this “tuning-fork”. The venation is normal in A. parva, as was to be expected since it lacks any trace of a brand.

Davidson et al. (1895) illustrated in colour the pupa of Ampittia maro (= dioscorides) showing that it had a pair of curved horns on the head of the pupa, not present in other genera of the Aeromachini. Kishen Das kindly sent pictures of the pupae of one Aeromachus and two Halpe that he bred in South India which are like Ampittia except for the absence of horns. Congdon recently bred A. capenas and found it to have similar horns (somewhat different horns are found also in members of the Pyrginae such as the black group of Celaenorrhinus (Cock & Congdon 2011b). He subsequently also bred A. kilombero (described as new below) that also has frontal horns (figure 3). A full description of the early stages of the two African species will be given in a future paper by Cock and Congdon (in press); both feed on soft grasses (Poaceae). Frontal horns are almost unknown within the Afrotropical Hesperiinae but are also found in Tsitana uitenhaga Evans in the form of small, upturned processes (Dickson & Kroon 1978: plate 22); these may not be exactly homologous since they are not lateral.

In the light of these shared special features—and somewhat to our surprise—we accept that the three African species are indeed congeneric with the Oriental Ampittia as well as with each other as the only members of the tribe Aeromachini in Africa.