Celaenorrhinus galenus biseriata ( Butler 1888 )

COCK, MATTHEW J. W. & CONGDON, T. COLIN E., 2011, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera) principally from Kenya. Part 3. Pyrginae: Celaenorrhinini, Zootaxa 3033 (1), pp. 1-67 : 28-32

Celaenorrhinus galenus biseriata ( Butler 1888) ( Figures 27–30 )

Van Someren (1939) found it fairly plentiful in the semi-clearings of the larger forests of the Chyulu Hills and Sevastopulo (1974) records it as common in both the Makardara Forest and the Marere Forest of the Shimba Hills. Even where it is found, I would regard it as occasional, rather than common, although the caterpillars are usually quite easy to find. Specimens from Meru Forest, which often forms a link between the Highland and Coast faunas, are all C. galenus opalinus , although perhaps larger than average for that subspecies .

Adult behaviour

Van Someren (1939) says that they are partial to patches of sunlight in the forest and settle on undergrowth, and that they are easier to catch in the late afternoon as they are less active at that time.

Food plants

I have reared subspecies biseriata from plants identified at that time as Hypoestes sp. (MJWC 075) at Kibwezi Forest (4 collections) and Hypoestes sp. ? verticillaris pink flowered form (MJWC 070) (3 collections) and H. verticillaris (2 collections) in the Shimba Hills. These are all treated as H. forskaolii today. In general the plants used by C. galenus biseriata seem to grow in more open situations than those used by C. galenus opalinus . Sevastopulo (1974, unpublished) reared this subspecies on Justicia sp. at Kwale; his illustrations of caterpillar and pupa match mine. This is probably the origin of Larsen’s (1991) record of Justicia sp. as the food plant of C. galenus , unattributed to subspecies.

Ovum

The ovum is white and weakly ribbed, but no specimens were available for detailed study. Ova are laid singly on the under surface of leaves in the middle of the lamina.

Leaf shelters

Stage 1 oval one-cut shelters are formed in the mid-lamina, hinged on a minor vein, e.g. 7 x 5 mm (89/108C), similar to those of C. galenus biseriata ( Figures 22.2 and 23 ). Stage 2 shelters may be oval one-cut shelters in the leaf lamina, e.g. 20 x 11 mm (89/108A), or may be two-cut shelters from the edge of the lamina, e.g. a triangular shelter 14 x 8 mm hinged on a main vein for an 8 mm caterpillar (89/108C), and a semi-oval shelter 16 x 9 mm hinged on a main vein for an n–2 instar caterpillar (89/101). The only stage 3 shelter found was a simple leaf fold from the edge of the lamina.

Caterpillar

Brief descriptions were prepared of the last three caterpillar instars of individual 89/101, collected on H. forskaolii in the Shimba Hills, 13 Dec 1981. Instar n–2 was 9 mm long and rested on the lid of its stage 2, two-cut shelter. The head was noted to resemble that of C. galenus opalinus , and the body was dark dull khaki green, with a narrow white dorsolateral line. It moulted three days later to the penultimate instar, which was 10 mm long when newly moulted. Head deeply and broadly indent at vertex; close to parallel sided; uniform dark reddish brown, except for a slightly darker line down centre of face. T1 white anteriorly, grey posteriorly. Body dull dark green with red tint; A8–A9 the red colouring is stronger; narrow, sharply defined white dorsolateral line T2–A7, becoming diffuse on A8; pale line along trachea; ventrally pale; legs concolorous; spiracles pale except that of A8 yellowish. Four days later, the caterpillar had grown to 15 mm, and it moulted to the final instar four days after that on 26 Dec 1981.

Two days after moulting to the final instar it measured 20 mm. At this point, I had run out of the original food plant and offered the caterpillar Hypoestes sp. (probably forskaolii ) from Kibwezi Forest, H. aristata and Justicia flava . The next day it did eat some of the H. aristata , but then appeared ill, regurgitating liquid and lying on its back. However, the next day, to my surprise, it settled down to feeding on H. aristata and continued development normally. By 4 Jan 1990, it measured 23 mm and looked relatively plump. Head almost quadrate, but deeply and broadly indent at vertex ( Figure 29.2 ); rugose; dark brown, except apices light brown with a weak streak of the same colour extending to half way down face. T1 as body. Body translucent dull white-green, apart from T1–A2 yellow green; body covered with white speckles except along dorsal line; narrow white dorsolateral line T2–A8; diffuse white ventrolateral line; legs concolorous; spiracles brown inconspicuous. By 9 Jan, larvae of Apanteles sp. were visible through the cuticle and these emerged from the body on 15 Jan, killing the caterpillar host ( Figure 30.1 ), which then measured 24 mm.

Head capsules of preserved remains were examined and measured: instar 2: uniform light brown, weak reticulated ridges, 0.8 x 0.8 mm (n=2); instar 3: head light brown with darker reticulated ridges, apex and steak down face smoother and ridges paler, apex posteriorly more rugose, 1.4 x 1.4 mm (n=6); instar 4: similar to instar 3, 2.1 x 2.1 mm (n=7); instar 5: brown with dark rather regular reticulated ridges, apex and streak on face smoother with pillars are very similar to those of C. galenus opalinus , but the head of that subspecies tends to be lighter brown, with the apices paler and the streak running down the face broader, although all these characters are variable. The full grown caterpillar of biseriata is larger ( Figure 29.3 28 mm), and this is reflected in the average size of the final head capsule: 3.1 x 3.1 mm for biseriata and 2.63 x 2.69 for opalinus.

Pupa

The pupa was not distinguished from that of C. galenus opalinus . Pupa durations noted were 11, 14 and 15 days.

Natural enemies

The caterpillars are commonly attacked by two Apanteles (s.l.) spp. From collections at the coast, I successfully reared adult C. galenus biseriata twice, and Apanteles three times, whereas from Kibwezi Forest I reared adult C. galenus biseriata four times and Apanteles twice ( Table 2). Apanteles sp. reared at the coast formed cocoons under the dead caterpillar in neatly arranged rows at right angles to the caterpillar embedded in silk flocculence ( Figure 30.1 ), whereas those reared at Kibwezi Forest formed their cocoons in slightly irregular rows on each side of the dead caterpillar, with the cocoons at right angles to the body embedded in a loose silk flocculence – similar to those observed to attack C. galenus opalinus . I anticipate that two different species of Apanteles are involved, one restricted to the coast, and the other to inland regions. Both species parasitize the early instars and emerge from the mature final instar caterpillar ( Table 2).

In addition to the Apanteles spp. , C. galenus biseriata is parasitized by a larval-pupal tachinid parasitoid. A penultimate instar caterpillar collected on Hypoestes sp. (probably forskaolii ) at Kibwezi Forest on 7 Mar 1991, pupated 29 Mar. By 4 Apr the pupa had turned pale brown ( Figure 30.2 ) and a tachinid larva could be seen moving within. The larva emerged the next day, and formed a puparium which emerged 19 days later on 24 Apr. It has not been identified.

Figures

FIGURE 22. Ovum and early shelters of Celaenorrhinus galenus opalinus. 1, ovum collected on Justicia flava, Kadera God Forest, Kisii, 5 Aug 1990; photographed 10 Aug; solitary parasitoid emerged 14–18 Aug; 90/85B1. 2, stage 1 shelter on Hypoestes aristata, containing instar n–3 caterpillar, Ngong Forest, Nairobi, 17 Sep 1989; reared; 89/56. 3, stage 2 shelter on H. aristata, containing n–1 caterpillar, Karen, Nairobi, 29 Oct 1989; reared; 89/82A.

FIGURE 23. Diagram of stage 1 and stage 2 leaf shelters of Celaenorrhinus galenus opalinus on Hypoestes aristata, Karen, Nairobi, 12 Aug 1987, 87/7; approximately life size. Light grey is the under surface of the leaf turned over to form the shelter; mid grey is the leaf upper surface. 1, stage 1 one-cut shelter that contained an instar 2 caterpillar. 2, stage 1 one-cut shelter (empty) and stage 2 one-cut shelter that contained an instar 3 caterpillar. 3, stage 1 one-cut shelter (empty) and stage 2 two-cut shelter that contained an instar 3 caterpillar.

FIGURE 27. Male Celaenorrhinus galenus biseriata. Collected as n–2 caterpillar on Hypoestes sp. (probably forskaolii), Kibwezi Forest, 31 Dec 1989; emerged and photographed 9 Feb 1990; 89/108A.

FIGURE 28. Celaenorrhinus galenus biseriata food plants. 1, Hypoestes forskaolii (identified as H. verticillaris white flower form), Shimba Hills (transplanted to Nairobi) 91.10.9. 2, H. forskaolii (identified as H. sp.?verticillaris pink flower form), Marere waterworks, Shimba Hills, 13 Dec 1990.

FIGURE 29. Caterpillar of Celaenorrhinus galenus biseriata. 1, n–2 instar caterpillar cutting stage 2 shelter; collected as n–3 caterpillar on Hypoestes forskaolii, Shimba Hills, 30 Mar 1989; photographed 1 May 1989; parasitized by Apanteles (s.l.) sp. 2; 89/24B. 2, detail of final instar head, collected as n–2 caterpillar on H. forskaolii (MJWC 070), Shimba Hills, 13 Dec 1989; moulted to final instar 26 Dec; photographed 27 Dec, 20 mm; parasitized by Apanteles (s.l.) sp. 2 in final instar; 89/101. 3, final instar, dorsolateral view; collected as n–2 caterpillar on Hypoestes sp. (probably H. forskaolii), Kibwezi Forest, 31 Dec 1989; moulted to final instar 10 Jan 1990; photographed 22 Jan, 28 mm; pupated 28 Jan; male emerged 6–9 Feb; 89/108A. 4, detail of final instar head; as (3).

FIGURE 30. Parasitisation of Celaenorrhinus galenus biseriata. 1, final instar caterpillar, lateral view with cocoons of Apanteles (s.l.) sp. 2, collected as n–2 caterpillar on Hypoestes forskaolii (MJWC 070), Shimba Hills, 13 Dec 1989; moulted to final instar 26 Dec; parasitoid larvae emerged 15 Jan; photographed 16 Jan, 24 mm; 89/101. 2, pupa parasitized by a tachinid (cf. normal colouring in Figure 25); collected as n–1 caterpillar on Hypoestes sp. (probably forskaolii), Kibwezi Forest, 7 Mar 1991; pupated 29 Mar; photographed 4 Apr, 19 mm; parasitoid emerged and formed puparium 5 Apr; adult tachinid 24 Apr; 91/13.