Prosopalpus styla Evans, 1937

Cock, Matthew J. W. & Congdon, T. Colin E., 2014, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 7. Hesperiinae incertae sedis: grass and bamboo feeders, Zootaxa 3872 (4), pp. 301-354 : 306-308

Prosopalpus styla Evans, 1937

Evans (1937) indicates that P. s t y l a, which occurs from Sierra Leone to Kenya is very similar to the type species of the genus: P. debilis (Plötz) (= P. duplex (Mabille) .

Gillies (1985) in Gambia observed: ‘Locally common resting in vegetation in high shade or low down among tall reeds along the river bank; sometimes flitting along the shady margins of rice fields and, in the early morning, sitting in open sites.’ Similarly, Larsen (2005) associated this species with ‘open swampland in both savannah and forest’. In our experience too, adults (Figure 3.1–2) are perhaps most frequently seen in areas of grass growing in standing water. There is (or was) one such patch in Kakamega Forest where the construction of the track partially damned a small stream, making a small shallow grass-covered pond (Figure 3.3); MJWC’s only three records of P. styla from Kenya are from this spot.

Food plants

TCEC has seen P. s t yl a oviposit on an unidentified grass ( Congdon & Collins 1998). MJWC noted several P. s t y l a in a water meadow between the forest and lake at IITA, Ibadan, Nigeria (20 Mar 1994), which led him to search the grass, Leersia hexandra , for hesperiid caterpillars. The two caterpillars found on this occasion (94/110) appeared to be of a Metisella sp. but this genus is submontane in Nigeria ( Larsen 2005) and would not occur at such a low altitude as Ibadan (200 m), so they are probably P. s t y l a. Their similarity to Metisella midas (Butler) , for example, will be apparent when we treat the Heteropterinae in a future contribution. Unfortunately neither caterpillar was reared through, so this food plant-caterpillar-adult association still awaits confirmation.

Leaf shelters

Caterpillar 94/110A appeared to be in the final instar and was found resting on the underside of a leaflet of L. hexandra , the surface of which was lightly silked, but not rolled, nor was there any sign of a shelter. In contrast caterpillar 94/110B appeared to be in the penultimate instar, about to moult, and was found in a shelter formed from the middle part of a leaf, rolled downwards. If these observations are representative, this is an unusual example where the final instar caterpillar does not form a shelter. If pupation is in the same situation, it seems likely that the pupa will be of the Baorini-type, as discussed in Cock & Congdon (2012), i.e. green with longitudinal lines and an elongate, pointed frontal spike.

Caterpillars

Caterpillar 94/110A ( Figure 4 ), which appeared to be in the final instar, measured 17mm. Head oval, widest near base; matt translucent dull green; stemmata black. Body dull yellow-green; dorsal line dark green, bordered by subdorsal whitish line; dorsolateral line pale yellow, with a dark green border dorsally and laterally; spiracles pale, inconspicuous; all legs concolorous.

Caterpillar 94/110B was in the previous instar preparing to moult and measured 13mm. Head translucent dull green; posterior margin narrowly black; dark brown line from apex laterally to stemmata; dark brown lines on epicranium from vertex, alongside epicranial suture and adfrontal suture to base of adfrontals. Pronotum black; narrow, wider laterally than dorsally. Body as final instar.

Imperata cylindrica (= I. South Africa Dickson & Kroon 1978, Clark (in Dickson arundinacea ) Pringle et al. 1994, Henning & Kroon 1978) et al. 1997

Cenchrus caudatus (= South Africa Pringle & Schlosz 1997 Pennisetum macrourum ) (Eastern Cape)

K. niveostriga Cenchrus caudatus (= South Africa Pringle & Schlosz 1997, Pringle & Schlosz schloszi (Pringle) Pennisetum macrourum ) (Western Cape) Woodhall 2005 1997 normal food plant

1 Some of these records are allocated to subspecies in the sources, but these are not treated separately here, apart from K. niveostriga .

Figures

FIGURE 4. Putative final instar caterpillar of Prosopalpus styla collected 20 Mar 1994 on Leersia hexandra, Ibadan, Nigeria; photographed 23 Mar; died; 19 mm; 94 / 110 A. 1, lateral / dorsolateral view; 2, detail of head, anterior view.