Gorgyra johnstoni Butler, 1894

Cock, Matthew J. W. & Congdon, Colin E., 2013, Observations on the Biology of Afrotropical Hesperiidae (Lepidoptera). Part 5. Hesperiinae incertae sedis: Dicotyledon Feeders, Zootaxa 3724 (1), pp. 1-85 : 12-14

Gorgyra johnstoni Butler, 1894

This species was described from Zambia, and is recorded from Mozambique and Zimbabwe to Zambia and Shaba ( DR Congo) north to the Kenya coast ( Ackery et al. 1995). In Kenya, it is restricted to the coastal area, where Sevastopulo (1974) records it as rare in Makardara and Marere Forests, Shimba Hills. The habitat in Tanzania is described as woodland, riverine forests and forest margins, from 400–1800m ( Kielland 1990). MJWC reared this species from the Shimba Hills, Kenya.

Adult behaviour

Although MJWC twice found caterpillars, he has not seen adults in the wild, yet it is relatively frequent in old collections (T.B. Larsen pers. comm. 2012). The adults ( Figure 11 ) seem to prefer partially shaded food plants for oviposition, along forest or scrub tracks.

Food plants

Sevastopulo (1974, 1975, unpublished) found the food plant of G. diva to be Rourea orientalis (= Byrsocarpus orientalis ) ( Connaraceae ), in the Shimba Hills. MJWC examined the food plant ( Figure 1 ) in the Shimba Hills and collected caterpillars of what he assumed at the time to be G. diva , but actually proved to be G. johnstoni .

Leaf shelters

The first shelter is a small flap (5–7 x 3–5mm) cut from the edge of the leaf lamina and folded upwards. The second shelter is formed from the basal half of a leaf, by cutting a notch from each margin to the mid rib at the centre of the leaf, and a small notch at the base of the leaf adjacent to, and parallel to the mid rib (see Figure 12 ); then folding the flap from each side upwards to meet over the mid rib, making a shelter 10–16mm long and 7–8mm wide. Some caterpillars make a second shelter similar to the first, but larger (e.g. 10 x 5mm). The third shelter is made by drawing together several leaves. Pupation may be in the third shelter, or in a single leaf shelter formed by folding it in half along the mid rib.

Ovum

A hatched ovum, probably of this species, was noted on a leaf undersurface, at the margin; it was similar to that of G. bibulus but smaller; white, rugose, finely reticulate, 0.67 x 0.35mm diameter x height.

Caterpillar

The caterpillar is green, with yellow speckles and a darker dorsal line ( Figures 12 and 13 ). Instar n-2 the black head measured 0.96 x 0.98mm wide x high (n=2). In the penultimate instar, the rounded oval head is dark brown with scattered light setae, 1.47 x 1.65mm wide x high (n=2); T1 concolorous; anal plate translucent brown ( Figure 12 ). In the final instar the head is reddish brown, with short, pale, scattered setae, stalked with a round plate on top, 2.35 x 2.35mm ( Figure 13 ); the anal plate is brown and the dorsal plate on T1 is not evident. A specimen with a dark brown head ( Figure 14 ) was probably this species, but was parasitised.

Pupa

The pupa ( Figure 15 ; 89/100B) is supported by a silk girdle; it is lightly dusted with white waxy powder, apart from the dorsal surface of the head which has a dense layer on it. The inside of the pupal shelter is also covered with the powder. 14mm; four days after formation (and three days after Figure 15 was taken) the abdomen, appendages and wing cases were translucent yellowish; thorax and head light brown; eyes protuberant; two small blunt frontal projections at an angle of about 45°; thorax, anterior and posterior parts of eye, apex of frontal projections with erect pale setae; spiracle T1 brown, slightly protuberant and fairly conspicuous. Pupation took 13 days.

Natural enemies

The medium grown caterpillars are commonly attacked by a gregarious eulophid, which forms 2–4 naked black pupae in the leaf shelter. The final instar is also parasitised by an Apanteles (s.l.) sp. ( Braconidae ), a gregarious species whose larvae spin a tight mass of flocullence in the leaf shelter within which they pupate for 16 days.

Figures

FIGURE 1. Rourea orientalis, a food plant of Gorgyra diva and G. johnstoni, Shimba Hills, 13 Apr 1990.

FIGURE 11. Adult female Gorgyra johnstoni, collected as caterpillar 13 Dec 1989 on Rourea orientalis, Shimba Hills, Kenya; adult 1 Jan 1990; 89/100B.

FIGURE 12. Penultimate instar caterpillar of Gorgyra johnstoni collected 13 Dec 1989 on Rourea orientalis, Shimba Hills, Kenya; moulted to penultimate instar 14 Dec; photographed 20 Dec, moulted to final instar 23 Dec; 15mm, 89/100C.

FIGURE 13. Final instar caterpillars of Gorgyra johnstoni, collected on Rourea orientalis, Shimba Hills, Kenya, 13 Dec 1989. 1, detail of head, anterodorsolateral view, photographed 14 Dec; pupated 19 Dec; 17mm; 89/100B; 2, detail of head, dorsolateral view, moulted to final instar 23 Dec; photographed 27 Dec; preserved in ethanol; 18mm; 89/100C; 3, as #2, dorsolateral view whole caterpillar.

FIGURE 14. Final instar caterpillar of Gorgyra sp., probably G. johnstoni, collected on Rourea orientalis, Shimba Hills, Kenya, collected 12 Apr 1990, photographed 17 Apr; parasitized 25 Apr; 18mm; 90/42.. 1, dorsolateral view; 2, detail of head, anterolateral view.

FIGURE 15. Pupa of Gorgyra johnstoni, collected 13 Dec 1989 on Rourea orientalis, Shimba Hills, Kenya; pupated 19 Dec 1989; photographed 20 Dec; adult 1 Jan 1990; 14mm; 89/100B.