Semalea arela Mabille, 1891

Cock, Matthew J. W., Congdon, T. Colin E. & Collins, Steve C., 2016, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 9. Hesperiinae incertae sedis: Zingiberales feeders, genera of unknown biology and an overview of the Hesperiinae incertae sedis, Zootaxa 4066 (3), pp. 201-247 : 211-214

Semalea arela Mabille, 1891

This species ( Figure 13 ) was described from Gabon ( Mabille 1891), and occurs from Senegal to Uganda and south to Zambia, and in coastal forests from Kenya to Mozambique ( Evans 1937, Ackery et al. 1995, Larsen 2005). The male has a brand on either side of the origin of vein 2 of the forewing. In Kenya, MJWC has found this species only in the Makadara Forest, Shimba Hills, where its food plant Aframomum orientale grows. However, it is known more widely from the Kenya coast and inland from Meru ( Larsen 1991), but does not seem to be known from the western forests. Although the adults are scarce in MJWC’s experience—perhaps because he has not visited the site in the first half of the morning when Larsen (1991) reports that the adults fly—the caterpillars are not difficult to find. In Tanzania, it is found wherever Aframomum spp. grow from 400 to 2000m (TCEC observations, Kielland 1990).

Food plants. Sevastopulo (unpublished) reared this species from an un-named species of Zingiberaceae in the Makadara Forest in the Shimba Hills, which he subsequently listed as Aframomum sp. ( Sevastopulo 1974) and Zingiber ( Sevastopulo 1975) . This is almost certainly the source of repeated records of Zingiber ( Kielland 1990, Larsen 1991, Ackery et al. 1995) or both Aframomum and Zingiber ( Heath et al. 2002, Vande weghe 2010). MJWC’s observations from the same locality are doubtless from the same population and food plant some 30 years later. The only food plant MJWC found there was Aframomum orientale which has individual mauve flowers at the base of the stems, and grows along the tracks, and around the edge of clearings in the Makadara Forest near the summit of the Shimba Hills. Almost certainly it is the same species which Sevastopulo recorded as Zingiber sp. and Aframomum sp. In captivity caterpillars accepted leaves of an ornamental Hedychium sp. with white flowers at the end of the leaf-frond (probably H. coronarium , native to Asia).

TCEC has reared this species from unspecified Aframomum sp(p). in Tanzania, Malawi and Mozambique. In Cote d’Ivoire, Vuattoux (1999) reared this species from Aframomum alboviolaceum (as A. latifolium ) and A. cereum (as A. sceptrum ). Larsen (2005) repeats these records and writes that ‘Condamin (mss) reports that Real bred it also from grasses ( Pennisetum , Setaria and Panicum ): I strongly doubt that a species could adapt to both grasses and Zingiberaceae .’ We agree with Larsen, and recommend that these records from grasses should not be accepted.

Ovum. MJWC believes that the ovum is as shown in Figure 14 , although he was not able to rear this specimen. It was laid on the under surface of a 215mm long leaf, 3mm from the edge, and 75mm from the tip. The ovum is 1.2mm in diameter, quite flattened, trapezoid in cross section, due to a flat top and ten flat faces around the perimeter, separated by distinct ridges which are thickened towards the apex. The ovum hatched after 5 days and the neonate caterpillar appeared to be a typical Hesperiinae .

Leaf shelters. MJWC observed that the young caterpillar cuts two notches from the edge of the leaf, and folds the resultant flap under, whereas larger caterpillars may cut a single large notch and fold a triangular flap under, normally using the distal part of the leaf, or roll the leaf from the edge without making a cut. TCEC found this last form to be typical, but whether this represents individual or geographical variation, we don’t know; systematic observations should be made. The shelters often trap water for extended periods after rain, but the caterpillars seem to suffer no ill effects.

Caterpillar. The newly hatched caterpillar (from the ovum in Figure 14 ) was pale with a black head, 0.5 x 0.5mm wide x high. As the caterpillar grows, subsequent instars until the penultimate instar (Figure 15.1) are translucent green, the head dark, instar n-3 0.8 x 0.9mm (n=1), instar n-2 1.25 x 1.5mm (n=1), instar n-1 1.8 x 2.2mm (n=5) wide x high. In the final instar (Figure 15.2–4), the head is a narrow oval, 2.55 x 3.4mm wide x high (n=5), indent at vertex, dark brown-black, shiny rugose; T1 concolorous with body; body translucent green, appearing yellow-green due to yellow dots over A1–A10; subcutaneous trachea and malpighian tubules visible through cuticle; spiracles pale, inconspicuous; all legs concolorous; anal plate semi-circular with a raised rim. The caterpillars from Kenya (Figure 15.1–3) and north-western Zambia (Figure 15.4) showed no significant differences.

Pupa. MJWC did not find the pupa in the field, but in captivity it was formed in the final leaf shelter. We have not explicitly documented whether there is a silk girdle, but S. pulvina (below) makes one, so there S. arela probably does too. We found no significant difference between the pupae from Kenya (Figure 16.3–6) and Zambia (Figure 16.1–2). A female pupa from Kenya, MJWC 89/25A (Figure 16.3–6) measured 22mm long; generally light brown with darker speckles; short flat-ended frontal projection; head very rugose; T1 spiracle surrounded, except anteriorly by a raised, smooth, brown lip, bordered exteriorly by a row of beading; other spiracles brown; proboscis sheath reaches tip of abdomen; dorsally on abdomen a pair of transverse lines, one each side of dorsum in mid segment; transverse row of indistinct spots posterior to these; large dark spots on A2 and A3 against wings; dorsolateral spot on A4–A6; final abdominal segment has a pale, raised, rugose dorsolateral ridge surrounding a smooth dorsal area. No white waxy powder. All six pupae that MJWC reared from three different collections took exactly 16 days to complete pupal development under Nairobi conditions.

Figures

FIGURE 13. Adult male Semalea arela at rest; reared from final instar caterpillar collected 18 Dec 1989, on Aframomum orientale, Makadara Forest, Shimba Hills, Kenya; adult emerged and photographed 11 Jan 1990; MJWC 89 / 102.

FIGURE 14. Putative hatched ovum of Semalea arela, collected on Aframomum orientale, Makadara Forest, Shimba Hills, Kenya, 30 Mar 1989; hatched and photographed 4 Apr; MJWC 89 / 25 I.