Ceratrichia semlikensis Joicey & Talbot, 1921

Cock, Matthew J. W. & Congdon, T. Colin E., 2014, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 7. Hesperiinae incertae sedis: grass and bamboo feeders, Zootaxa 3872 (4), pp. 301-354 : 313-315

Ceratrichia semlikensis Joicey & Talbot, 1921

Joicey & Talbot (1921) described ssp. semlikensis from Semliki Valley, Eastern DR Congo, as a subspecies of the West African C. flava Hewitson. Recently, Collins et al. (2004) raised it to a full species, as C. flava and C. semlikensis overlap in the Central African Republic, and there are differences in the male genitalia. Ceratrichia semlikensis is now known to be found in western Kenya, Uganda, central and eastern DR Congo, Central African Republic, north-western Tanzania and north-western Zambia ( Evans 1937, Ackery et al. 1995, Kielland 1990, Heath et al. 2002, Collins et al. 2004). MJWC is familiar with it from Kakamega Forest, western Kenya, where it is common, and normally seen on every visit.

Adult behaviour

The adults fly along shady paths and in slightly open forest, pausing frequently to rest on vegetation. They pause in clearings and along the edge of open tracks and roads to sun themselves and feed at flowers ( Figure 9 ). Flight continues late into the afternoon.

Food plants

The food plant MJWC found in Kakamega Forest, Kenya, is a fine-leaved, sprawling grass, Isachne mauritiana , which forms an open ground cover beside paths in the forest.

Ovum

On 21 Sep 1991, MJWC observed a female at 16.00h showing oviposition behaviour beside the track up the hill from where the D267 crosses Ikuywa Stream, Kakamega Forest. She fluttered around low growth of Isachne mauritiana partially screened by overhanging growth. She alighted on a grass blade, made a short, slow flight to another, and alighted again, doing this about five times. She then settled on a small dead twig on the ground and curled her abdomen around under the twig and appeared to oviposit. The sequence of short flights and landing on grass blades was repeated, and she settled on a dead bit of plant material and appeared to oviposit again; once again the cycle was repeated and she appeared to lay an ovum on a dead leaf, before flying off a short distance and resting on a leaf. MJWC then photographed and caught the female, and later extracted two ova from her abdomen; one of these was posed on the dead twig to take the photograph shown here (Figure 10.1). The ovum is red, weakly striated, dome-shaped, slightly taller than wide, with a flange around the base.

MJWC collected all three bits of debris on which she had appeared to oviposit, but when they were checked, there were no ova on them. It is possible that the female did lay an ovum each time, but instead of sticking them to the dead debris she let them drop to the ground. This seems unlikely inasmuch as when MJWC found caterpillars a few minutes later (91/62), one of them was associated with the base of an ovum on the same leaf. We hope someone will get a chance to make more observations and clear this mystery up.

Leaf shelters

Armed with the clue of the probable food plant which led the female to show oviposition behaviour as described above, MJWC immediately searched the area and located caterpillars of what proved to be C. semlikensis on I. mauritiana growing on the other side of the track, almost completely shaded by the shrub layer. The shelters were made by rolling the basal portion of a leaf, the distal part of which had been eaten. As noted above, the penultimate instar caterpillar shelter (91/62B) was made from a leaf which also had the base of an eclosed ovum on it, which is likely to be the ovum from which that caterpillar hatched.

Caterpillar

The final instar caterpillar (91/62A) measured 12mm when collected (Figure 10.3), and pupated 12 days later; head 1.95 x 2.2 mm wide x high (n=4), widest in ventral half, tapering to apex, indent at vertex; shiny, rugose; ground colour green-brown, covered with dark indent dots except centrally on face; stemmata in black patch, with yellow area anterior to this; body pale yellow-green; narrow darker dorsal line; broader, but more diffuse lateral line; the lines more clearly defined on T2–3; spiracles pale inconspicuous. The mature caterpillar develops wax glands all over the ventral surface from A1 to A8, extending between the prolegs, but not lateral to them.

The penultimate instar caterpillar (91/62B) was similar; head 1.5 x 1.6 mm wide x high (n=2), light shiny brown, frons dark brown (Figure 10.2); posterior margin of head narrowly dark. The same n-2 instar premoult caterpillar measured 7 mm; head 1.1 x 1.2mm wide x high (n=1); head uniform light brown; otherwise similar to the penultimate instar.

Pupa

In captivity, pupation occurred on the base of the rearing container, at the angle with the vertical wall. The outer ‘defence’ was a row of five or six stout strands of silk across the angle between bottom and wall, although in the field these strands would have shortened and drawn together the material to which they were attached, perhaps making a more secure shelter. Within this, and linked to several of the central outer strands, was an open network of stout strands, with some loose white waxy powder. The pupa was very light brown, with a blunt, almost square head, and indented slightly between the head and neck. It did not have a wax coating, and the proboscis sheath projected 2mm beyond the tip of the cremaster. Because the caterpillars ignored the available leaves when preparing for pupation, we speculate they may leave the food plant to pupate amongst litter on the ground. The pupal period lasted about 16 days.

Figures

FIGURE 9. Adults of Ceratrichia semlikensis, Kakamega Forest, Kenya. 1, at rest, 22 Sep 1991; 2, male sunbathing, 17 Jun 1991; 3, female sunbathing, 1 Jul 1990.