Metisella medea medea Evans, 1937

Cock, Matthew J. W. & Congdon, T. Colin E., 2017, Observations on the Biology of Afrotropical Hesperiidae (Lepidoptera) with particular reference to Kenya. Part 11. Heteropterinae, Zootaxa 4226 (4), pp. 487-508 : 492-494

Metisella medea medea Evans, 1937

Evans (1937) described this species from Mt Kenya, and attributed to it a few additional specimens from Congo, Uganda and Tanzania. Evans also described a second subspecies, nyika Evans, from Kusungu, Mt. Malawi , but Larsen (2005) indicates this is a separate species. A disjunct population in Nigeria and / or Cameroon may represent a separate species or subspecies ( Larsen 2005). De Jong (1976) illustrates the male genitalia of the nominate subspecies.

Widespread in the highlands of Kenya, this is more of a mountain species than perhaps any other skipper in Kenya. MJWC has found it on the Escarpment side of the Aberdares on the lower side of the rain forest, and through most of the rain forest on the North-east side of Mt Kenya . He has not seen adults on the Ngong Hills, near Nairobi, but collected two caterpillars there close to the highest parts in October 1989 ( MJWC 89 /72). Kielland (1990) associates this species with ‘highland open habitats, montane forests and riversides from 1000 to 2700 m’ in Tanzania .

Adult behaviour. The adults seen in Kenya ( Figure 4 ) were found beside the road in open parts of the forest. They sunbathe resting on vegetation and come to flowers.

Food plants. Unfortunately, when MJWC collected the two caterpillars on Ngong Hills, two grasses, Helictotrichon elongatum and Ehrharta erecta (identified as var. abyssinica ), were mixed together. The food plant is at least one of these (probably E. erecta ) or perhaps both. In captivity the caterpillars accepted Cenchrus trachyphyllus (= Pennisetum trachyphyllum ) as well as an unidentified lawn grass (referred to locally as 'Karen grass'). Larsen (1991) reports the food plants as ‘various grasses’ and includes MJWC’s unconfirmed record from Ehrharta . Subsequently, he gives the food plants as ‘Poaceae’ ( Larsen 2005).

Leaf shelters. The fourth instar caterpillars made a leaf roll with the apical part of a leaf rolled downwards, and fed basally to this.

Caterpillar. The early instars are striped green with a black head. The head of the penultimate instar (Figure 5.1) measures 1.2 x 1.35mm wide x high (n=2); dark brown-black, very slightly paler on face over frons and adfrontals; shiny, weakly rugose on epicranium, smooth on adfrontals, frons and clypeus; scattered short, fine, dark setae; adfrontal suture scarcely evident; frontal suture marked by a row of small pits; adfrontal smoothly and lightly grooved at right angles to the sutures; frons with a row of vertical grooves across base and another across middle. Pronotum narrow, black. Body green with strong subdorsal and dorsolateral pale stripes and a weak lateral pale stripe.

The final instar caterpillar (Figure 5.2–4) was 16mm long when newly moulted and grew to at least 21mm; the head measured 1.6 x 2.0mm wide a high (n=2); matt, weakly rugose on epicranium, smooth on adfrontals and frons; scattered short, fine, pale setae. In individual 89/72 A (Figure 5.3) the head was dull green (the cuticle is translucent), with a broad black line from apex to stemmata, a narrow line extending posteriorly along basal stemmata. In contrast, the head of individual 89/72B ( Figure 5 , 2 , 4 ) was dark blackish brown with a broad dull green stripe from apex along narrowly dark epicranial suture, across adfrontals, frons and clypeus; a diffuse green posterolateral line in basal part of head and a large ventrolateral green patch over stemmata. Pronotum transparent green in individual 89/72 A, diffusely dark dorsolaterally with a lateral dark spot in individual 89/72B. Body dull green; two narrow, yellow-white subdorsal lines; thicker, white dorsolateral lines; narrow yellow-white lateral line becoming white posteriorly; scattered very short, very fine, pale setae; anal plate with longer, erect, pale setae, darker on posterior margin; legs pale brown; prolegs concolorous with body; spiracles pale inconspicuous. The final instar lasted 8–11 days.

Pupa. The pupa is 16mm long with a short blunt, slightly upturned frontal spike 1.6mm long, 1.0mm wide at base; proboscis sheath to end of wings only; cuticle transparent; slightly darker dorsal line from frontal spike to cremaster; pale yellow subdorsal line on thorax of 89/72 A but not 89/72B; pale dorsolateral line from T2 to A 8, which may be yellowish on thorax; one or two whitish lateral lines on abdomen; individual 89/72B also has an interrupted weak dark line from head above eyes, to small dark spiracle T1, to base of wings. The body contents show through as light green becoming pale yellow ( Figure 6 ) and then showing the adult colouring. The pupal stage lasts about 12 days.

Figures

FIGURE 2. Early stages of Metisella midas midas, collected on Leersia hexandra, Kyuna Estate, Nairobi. 1, Ovum, 15 Feb 1989; 89 / 86; 2, leaf shelter, 12 Nov 1989; 3, instar 4 caterpillar, collected 14 Oct 1989; photographed 16 Oct 1989; 7 mm; parasitized; 89 / 80 A; 4, head of instar 4 caterpillar, collected 20 Jan 1990; moulted to final instar approx. 1 Feb; photographed 5 Feb 1990; parasitoid emerged 11 Feb; 90 / 6 F, 5, final instar 5 caterpillar, dorsolateral view; collected 12 Mar 1989; photographed 12 Mar 1989; pupated 17 Mar; 20 mm; 89 / 9 A; 6, as # 5, detail of head, anterodorsolateral view.

FIGURE 4. Adult female Metisella medea medea, collected as caterpillar on unidentified grass, Ngong Hills, 1 Oct 1989; adult 22 - 23 Oct; photographed 23 Oct; 89 / 72 A. 1, showing partial view of upper side; 2, under side.

FIGURE 5. Caterpillars of Metisella medea medea, collected on grass, Ngong Hills, 1 Oct 1989. 1, penultimate instar caterpillar anterior region, dorsal view; photographed 2 Oct; moulted 8 Oct; 10 mm; 89 / 72 B; 2, final instar caterpillar anterior region, dorsolateral view; moulted to final instar 8 Oct; photographed 11 Oct; pupated 19 Oct; 21 mm; 89 / 72 B; 3, final instar caterpillar, dorsolateral view; moulted to final instar 2 Oct; photographed 2 Oct; pupated 10 Oct; 16 mm; 89 / 72 A; 4, prepupa, dorsal view; photographed 18 Oct; 16 mm; 89 / 72 B.

FIGURE 6. Pupa of Metisella medea medea, dorsal view; collected 1 Oct 1989 on grass, Ngong Hills; pupated 19 Oct; photographed 20 Oct; adult 31 Oct; 16 mm; 89 / 72 B.