Spialia kituina Karsch, 1896

Cock, Matthew J. W., 2016, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera) with particular reference to Kenya. Part 10. Pyrginae, Carcharodini, Zootaxa 4173 (4), pp. 301-350 : 305-307

Spialia kituina Karsch, 1896

De Jong (1978) placed S. kituina in his asterodia group, along with S. asterodia and S. agylla . G.C. Clark (in Dickson & Kroon 1978) illustrated a detailed life history of A. asterodia , and Henning et al. (1997) illustrates a caterpillar and pupa of S. agylla .

The type locality for S. kituina is Kitui, 180km east of Nairobi , Kenya ( Karsch 1896, De Jong 1978), not Zanzibar as given by Evans (1937). Pyrgus bettoni Butler, 1898 described from Maungu, southeast of Voi on the Mombasa Road , Kenya is a synonym of S. kituina . This species is quite widespread in dry forests of eastern Kenya extending into the Rift Valley (Magadi Road), while De Jong (1978) also gives a record for Logichokio in northwest Kenya. It is one of the few entirely endemic Kenyan skippers, although its presence in neighbouring countries is not unlikely.

Normally this is a rare species ( Larsen 1991), e.g. Sevastopulo (1974) records it as uncommon on the outskirts of Makardara and Marere Forests, Shimba Hills. It tends to be found in small groups of two or three, although once I found it common in Kibwezi Forest (29 Apr 1990).

Adult behaviour. Flight is low and rapid interspersed with resting on low vegetation and feeding at low flowers. I have seen a male use a dried grass inflorescence about 50 cm tall as a perch to defend a territory, returning for short periods to his perch.

Food plants. Van Someren (1974) gives Sida spp. as the food plants in East Africa, in which he is followed by Larsen (1991). I found the caterpillars on a patch of Hermannia exappendiculata at the edge of Jadini Forest behind Diani Beach ( MJWC 90 /109). The following account is based on this material. Similar caterpillars which I was unable to rear were twice found on the same food plant at Kibwezi Forest .

Ovum. The ovum ( Figure 2 ) is laid on the abaxial surface of a young leaf, near the margin, or on the terminal, small young leaves. It may be that they are only laid on the youngest leaves, and those I have observed near the margin on the leaf abaxial surface were originally laid there but the leaf has expanded and opened subsequently. Although I believe it correctly identified, the ovum illustrated could be that of S. zebra (Butler) , which also fed upon H. exappendiculata in the same area. However, I have associated a slightly different ovum with S. zebra ( Figure 27 ), which is more globular, with more continuous lateral ridges. The ovum treated as S. kituina here (MJWC 90/109) is 0.62mm in diameter, and has a series of irregular ridge-like protuberances in rows around the circumference, about 20 slightly above the base, a row of 18 above this, then of 14 and finally a circle of six around the micropyle. In some cases the ridges in successive rows run into each other, but often not.

Leaf shelters. The leaf shelters are made by folding a leaf in half upwards and binding the edges together. Usually the whole leaf is used, but one shelter using the distal portion only was found. Older caterpillars seem to move onto younger leaves with successive shelters.

Caterpillar. There appears to be five instars. In the final instar ( Figure 3 ), the caterpillar head measures 2.1 x 1.9mm wide x high (n=3); dark brown, rugose, shiny; long, erect, pale, simple setae of about 0.35mm; similar, but dark setae on apices and less densely laterally; face from vertex to base of frons and almost to lateral edge with short, pale, recumbent, aciculate setae, except for a bare patch on each epicranium about one-quarter of the width of the face; these aciculate setae capture and hold white waxy powder at pupation. Pronotum concolorous with body, or paler; a very narrow slightly undulating dark line towards the posterior margin; about 20 long, pale, erect, simple setae. Body yellow-green, dorsal line and two lateral lines darker, scattered yellow-white dots; body covered with short, erect setae, bifurcate just before apex; anal plate with simple setae around margin; legs concolorous; spiracles inconspicuous. The caterpillar is superficially similar to others of the genus, but the uniform concolorous colouring of T1 (brown in the penultimate instar), is distinctive, lacking the contrasting white spots found in other species that I have reared.

In the penultimate instar, the head ( Figure 4 ) measures 1.45 x 1.5mm wide x high (n=2). A 10.5mm caterpillar in the penultimate instar (MJWC 90/109) had the head brown, with long, pale, erect, simple setae, together with darker ones on apices and laterally; short, pale, recumbent, aciculate setae across face, except for a variable bare patch on each epicranium. Pronotum uniformly brown, except darker on posterior margin. Body dull yellow-green, dorsal line darker, dorsolateral and lateral lines lighter; scattered yellow dots and long, pale, erect setae, bifurcate just before apex.

The preceding two instars are similar. The head of the Ln-2 caterpillar measures 1.1 x 1.1mm (n=2), while that of the Ln-3 instar measures 0.8 x 0.8mm (n=1). Given that the ovum is externally only 0.62mm in diameter (above), there is probably only one earlier instar. The head of the Ln-2 caterpillar is brown rather than dark brown, and there are no dark setae and no area bare of aciculate setae on the face. The head of the Ln-3 caterpillar has rather uniform short, erect, pale setae. The smallest caterpillars feed upon the leaf upper surface and skeletonise it.

Pupa. Pupa MJWC 90/109 A (Figure 5.2) was 11mm long, 3mm at widest; head, thorax and dorsal abdomen dark; appendages and abdomen ventrally translucent; lightly covered with white waxy powder; spiracle T1 0.76mm wide (dorso-ventrally), 0.4mm long (antero-posteriorly), dark and protruding, the posterior margin is a black fluted vertical wall of 0.20mm, and the anterior portion slopes down to the surface of the pupa; a row of four wax-free patches dorsally on A 1–3 giving a tessellated appearance; proboscis to end of wing sheaths; cremaster narrow; pupa covered with short, slender, pale, setae except on appendages; no brown plaques discernable. The pupal stage lasts 12–14 days.

Natural enemies. Two caterpillars collected at Kibwezi (MJWC 89/29) were parasitized by a solitary larval endoparasitoid Microgasterinae , the larvae of which emerged from fifth instar host caterpillars to spin a 5mm long white cocoon in a very loose flocculence of white silk in the leaf shelter (Figure 5.1). The adult emerged after 11 days.

Figures

FIGURE 2. Three views of an ovum of Spialia kituina, collected on Hermannia exappendiculata, Diana Beach, 12 Dec 1990; MJWC 90 / 109. 1, dorsal view; 2, dorsolateral view; 3, lateral view.

FIGURE 3. Final instar caterpillar of Spialia kituina, collected on Hermannia exappendiculata, Diana Beach, 12 Dec 1990; moulted to final instar approximately 16 Dec; pupated 11 Jan 1991; MJWC 90 / 109 A. 1, dorsolateral view; photographed 20 Dec; 13 mm. 2, lateral view; photographed 27 Dec. 3, detail of head, anterolateral view; as # 2.

FIGURE 4. Penultimate instar caterpillar of Spialia kituina, collected on Hermannia exappendiculata, Diana Beach, 12 Dec 1990; photographed 13 Dec; moulted to final instar approximately 16 Dec; 11 mm; MJWC 90 / 109 A. 1, dorsolateral view. 2, head and thorax, dorsal view.

FIGURE 27. Probably ovum of Spialia zebra bifida, collected on Hermannia sp., Kibwezi Forest, 7 Mar 1991; died; collected in association with caterpillars of S. zebra, but S. kituina also feeds on this host at this locality; MJWC 91 / 11. 1, dorsolateral view when relatively fresh; photographed 18 Mar; 2, dorsal view when dead; the caterpillar appears to have eaten part of the dorsal shell leaving the ridges and the black head is partially visible; photographed 28 Mar.