Semalea pulvina Plötz, 1879

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 : 215-219

Semalea pulvina Plötz, 1879

Semalea pulvina was described from Aburi, Ghana ( Plötz 1879), and is found from West Africa east to western Kenya and South to Zimbabwe and Mozambique ( Larsen 1991, Ackery et al. 1995, Larsen 2005). The southern populations Mozambique, Malawi, Zimbabwe, Zambia, and Shaba ( DR Congo) have a much lighter ground colour and T.B. Larsen (pers. comm. 2015) intended to describe them as a separate subspecies. The male of this species has distinctive secondary sexual characteristics, most notably a large, dark brand over the cell and costa UPH, matched by a forward directed hair tuft on dorsum UNF.

Kakamega Forest is the Kenyan stronghold of this species, although MJWC has a single male from Meru Forest, and Neave (1904) records a single male from Ugaia, South of Kisumu. MJWC has seen adult males once in Kakamega Forest, when they came readily to flowers. Females ( Figure 17 ) settle on low vegetation in clearings. Although neither sex is frequently seen, caterpillars are easy to find on their food plant in Kakamega Forest: Aframomum zambesiacum zambesiacum . Adults are said to be active early in the morning only, disappearing before midday ( Dickson & Kroon 1978).

Food plants. Dickson & Kroon (1978) give the food plant as wild ginger, Siphonochilus aethiopicus (= Kaempferia aethiopica ) ( Zingiberaceae ) in southern Africa. This record is repeated (as Kaempferia aethiopica ) by Kielland (1990) and (as Kaempferia ) by Larsen (1991) and Ackery et al. (1995). Pringle et al. (1994) and Heath et al. (2002) refer to the same food plant in the new combination S. aethiopicus , and Heath et al. (2002) add Aframomum sp. ( Zingiberaceae ), probably based on TCEC’s rearing. Larsen (2005) lists all three genera: ‘ Aframomum , Siphonochilus ( Zambia) and Kaempferia ’, and Vande weghe (2010) lists the same three genera.

The food plant in Kakamega Forest, western Kenya, is Aframomum zambesiacum zambesiacum , a large species which grows beside the roads and tracks over much of the area. The fruiting body is only present rarely; it is a large red body at the base of the stalks ( Figure 18 ); MJWC saw the fruiting body once, but no flowers. TCEC reared this species from Aframomum sp. at Tukuyu (south-western Tanzania), Lulanda (forest at 1500–1700m, near Mufindi, Iringa, Tanzania), Rondo (south-eastern Tanzania) and Hillwood (north-western Zambia). Where the ranges of S. arela and S. pulvina overlap, TCEC has found them on the same plants, even on the same leaf.

Ovum. TCEC recorded the ovum from the Rondo Plateau ( Figure 19 ). It is orange-brown, dome-shaped, with a strong basal flange, 13 wall-like ribs stopping short of the micropyle, and horizontal microsculpture between the ribs.

Leaf shelters. These are similar to those of S. arela described above, except this species tends to fold the shelters upwards more often. The largest shelters may be formed from the basal half of a leaf with one half folded under or over along the mid-rib, and the distal portion eaten. TCEC found that S. pulvina normally cuts a flap, whereas S. arela normally rolls a leaf without making a cut. If this behaviour is followed by feeding basal and or distal to the shelter, it will appear as though the shelter construction involved a cut. As noted under S. arela , more systematic observations of shelter construction in these species would be helpful. As for S. arela , the shelters often trap water after rain, without adversely affecting the caterpillars.

Caterpillar. The final instar caterpillar of individual MJWC 89/37B (which subsequently died) measured 24mm (Figure 20.2–3); head 2.2 x 2.7mm wide x high (n= 10), oval, indent at vertex; brown, with a lighter brown stripe on the epicranium each side of epicranial suture and on outer edge of adfrontals and the clypeus, laterally to stemmata; rugose, shiny. T1 with a very narrow, inconspicuous brown band on pronotum, otherwise concolorous with body. Body translucent dull dark green, the subcutaneous trachea visible through the cuticle; a brown dorsolateral stripe, continuous T1–A1, narrower A1–A4, starting to break up A5–A8, upturned on A8; a ventrolateral flange to body; spiracles pale, may be quite conspicuous, linked by visible trachea; all legs concolorous. The instar lasts 14–17 days, and the body turns brown before pupation (Figure 20.4). Caterpillars from Zambia (Figure 20.5) would be placed in a separate, southern subspecies by T.B. Larsen (above); they were similar to those of what would be the nominate subspecies, but the brown of the head may have more of a red tone.

The penultimate instar caterpillar MJWC 89/37D is similar (Figure 20.1) but the head is 1.6 x 1.8mm wide x high (n=4) uniformly brown apart from a diffuse area at apex and the clypeus and lower frons being light brown; the dorsolateral line is less pronounced. The fourth instar lasts about 12 days. In instar n-2, the light brown head measured 1.1 x 1.2mm wide x high (n=2).

The final instar caterpillar and pupa of Xanthodisca vibius (Hewitson) which feeds on the same food plant are very similar, and differences are discussed under that species.

Pupa. The pupa ( Figure 21 ) is similar to that of S. arela , but lacks the frontal projection, and the proboscis extends 2–3 segments beyond the wing cases. The pupa is attached at the cremaster to a solid bar of silk, across the wall of the shelter, and there is a weak silk girdle. A Kenyan pupa (MJWC 90/37A, Figure 21.1) probably formed a week previously had the head and appendages dull brown; abdomen light chestnut brown; spiracle T1 light chestnut, similar in structure to that of S. arela , the central hole 0.3mm in diameter and the variably brown border about 0.5mm wide; a small dark patch around spiracles A4–A6. Pupae are variably speckled, some having almost no speckles, others heavily speckled. Some pupae have irregular dark spots subdorsally above the T1 spiracle, and dorsolaterally on the anterior margin of T3 and A1 (similar to Xanthodisca vibius discussed below). The pupal stage lasts about 17 days (range 9-21). A Zambian pupa (Figure 21.2–3) is similar but the border of the T1 spiracle is brown, and the abdomen has a darker lateral line, which appears to be due to the colouring of the dorsolateral line of the caterpillar persisting in a recently formed pupa. No white waxy powder.

Figures

FIGURE 17. Adult female of Semalea pulvina, collected as final instar caterpillar on Aframomum zambesiacum zambesiacum, Kakamega Forest, Kenya, 6 Apr 1990; adult emerged and photographed 25 Apr 1990; MJWC 90 / 37 A.

FIGURE 18. Developing fruiting bodies of Aframomum zambesiacum zambesiacum, Kakamega Forest, Kenya, 1 Jul 1990.

FIGURE 19. Ovum of Semalea pulvina, collected on Aframomum sp., Rondo Plateau, south-east Tanzania, 3 Apr 1998 [TCEC].

FIGURE 21. Pupae of Semalea pulvina. 1, dorsolateral view, collected as final instar on Aframomum zambesiacum zambesiacum 6 Apr 1990, Kakamega Forest, Kenya; pupated 9 – 16 Apr; photographed 17 Apr; adult female 25 Apr; 20 mm; MJWC 90 / 37 A. 2 – 3, collected on Aframomum sp., Hillwood, north-western Zambia; photographed 11 May 2000 [TCEC]; 2, dorsal view; 3, dorsolateral view.