Caenides dacena Hewitson, 1876

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 : 226-227

Caenides dacena Hewitson, 1876

Hewitson (1876) described this species from Gaboon, i.e. Gabon and it is found from Sierra Leone to Uganda, South Sudan and north-west Tanzania ( Evans 1937, Ackery et al. 1995, Congdon & Collins 1998). As noted above, this species does not belong in Caenides , and will require a new genus ( Larsen & Collins 2011, 2014).

In his key to Caenides, Evans (1937) treats C. dacena has having neither a hindwing hair tuft nor a forewing brand. However, the material reared by MJWC from Cameroon has a distinct forewing brand in space 2, starting below vein 3 half way between the origin of vein 3 and the spot in space 3, running adjacent to vein 3 and then adjacent to the cell, before turning away from the cell to meet vein two, with a short broad extension below vein 2 in space 1b. SCC examined material in ABRI collected from Côte d’Ivoire to Uganda, and found that two-thirds of males had a brand visible using a hand lens, although this was most obvious when the wings were at a slight angle to the viewer, i.e. with wings depressed or slightly sprung. It may be that the brand is not always present, that it is only obvious in newly emerged specimens, or could more than one species be involved?

Food plants. Vuattoux (1999) reared this species four times in Côte d’Ivoire from Costus afer (Costaceae) . This record is repeated by Vande weghe (2010). MJWC reared a specimen from the Costus sp. shown in Figure 28 , near Douala, Cameroon ( MJWC 90/206). In discussion with Martin Cheek (Royal Botanic Gardens, Kew), we concluded that this photograph represents either C. afer or C. lucanusianus , although the latter has also been treated as a synonym of C. afer and/or C. maculatus (Tropicos 2014) . In captivity, two caterpillars in the final instar completed feeding when offered leaves of Hedychium sp. and Aframomum sp. but the resultant adults were significantly smaller than others reared through on Costus .

Leaf shelters. The one-cut shelters of the penultimate and final instar caterpillars are made with a cut from the edge of the leaf lamina to close to the midrib, and the distal part of the leaf is then folded upwards.

Caterpillar. The penultimate instar caterpillar had a uniformly black or very dark brown head; rugose; 2.5 x 2.9mm wide x high (n=2). The final instar caterpillar ( Figure 29 ) measured 38mm, five days before pupation. Head 3.6 x 4.4mm wide x high (n=4); indented at vertex; shiny, rugose; very dark brown, except for indistinct dark brown markings: a line down the centre of the frons, a line parallel and close to epicranial suture and a weaker line down face below the apex, which is not always present. These head markings are easily overlooked in life. Their distribution is reminiscent of those of Hypoleucis ophiusa ( Figure 26 ). Pronotum brown. Body transparent greenbrown; darker dorsal line; rest of body with pale fat bodies showing through cuticle; anal plate dark with pale margin; spiracles light brown, not conspicuous; all legs concolorous. The body becomes brown ventrally at the end of the final instar; the wax glands are restricted to the anterior ventral margin of A1 according to MJWC’s notes, but it would be worth confirming this unusual distribution.

Pupa. The pupa is formed in the final leaf shelter. It was not described, but it was photographed ( Figure 30 ). The proboscis extends to at least the base of the cremaster, sometimes to the tip. There is a pale brown C-shaped raised rim around the posterior side of the T1 spiracle, measuring 0.7mm across dorsoventrally, and variably 0.4– 0.6mm across the rim; this rim surrounds a dark brown conical pit. This feature is also present in C. dacela (Cock et al. 2014, Figure 55). The pupal stage lasted 25–29 days.

Figures

FIGURE 26. Caterpillars of Hypoleucis ophiusa ophiusa, collected on Costus sp., Forêt du Yapo, Côte d’Ivoire, 3 Jun 1989; MJWC 89 / 213 B. 1, penultimate instar, detail of head in anterodorsal view; moulted and photographed 14 Jun; 15 mm; 2, final instar, detail of head in anterodorsolateral view; moulted and photographed 14 Jun; 21 mm; 3, final instar, dorsolateral view, as # 2.

FIGURE 28. Costus afer or C. lucanusianus, the food plant of Caenides dacena, Douala, Cameroon, 16 Jun 1990, MJWC 90 / 206.

FIGURE 29. Final instar caterpillar of Caenides dacena collected on Costus sp. near Douala, Cameroon, 16 Jun 1990; 38 mm; MJWC 90 / 206 A. 1, head anterolateral view; 2, dorsolateral view.

FIGURE 30. Pupa of Caenides dacena, lateral view; collected on Costus sp. near Douala, Cameroon, 16 Jun 1990; pupated and photographed 15 Jul; MJWC 90 / 206 D; 22 mm.