Pteroteinon caenira Hewitson, 1867

Cock, Matthew J. W., Congdon, Colin E. & Collins, Steve C., 2014, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 6. Hesperiinae incertae sedis: palm feeders, Zootaxa 3831 (1), pp. 1-61 : 44-46

Pteroteinon caenira Hewitson, 1867 (in Hewitson 1867 –1871)

This species forms a part of a small group of closely related species, the others being P. ceucaenira (Druce) and the recently described P. concaenira Belcastro & Larsen ( Larsen 2005) and P. komo Vande weghe from Gabon (Vande weghe 2009). The first three species have clear genitalia differences (T.B. Larsen pers. comm. 2013) but the genitalia of P. komo have not been documented yet. Pteroteinon caenira (Hewitson) ( Figure 43 ) is found from Sierra Leone, though West Africa to Central African Republic, DR Congo, western Uganda and northern Zambia ( Larsen 2005). Previous reports of P. ceucaenira in Tanzania (e.g. Congdon & Collins 1998) are incorrect, the specimens actually being a new subspecies of concaenira or caenira , or even a distinct species (T.B. Larsen pers. comm. 2014).

Food plants. Vuattoux (1999) reports rearing this species from introduced palms only in Côte d’Ivoire ( Phoenix dactylifera and Washingtonia filifera ) but as he notes, it can be expected to have indigenous palms as food plants as well. MJWC (in Larsen 2005) found early stages of this species on an ornamental palm at Ibadan, Nigeria (94/101); at the time, this was thought to be an ‘ Areca sp.’, but most likely was Dypsis lutescens . Larsen (2005) notes that these records may refer to any of the three species of this small complex of Pteroteinon spp. MJWC found one final instar caterpillar (94/101A), a pupa which died formed up (94/101B, Figure 45.3 ), and two dead pupae (94/101C, D), one of which was missing the head probably due to a predator, but had fully formed up showing the distinctive male forewing markings of P. caenira (94/101D, Figure 45.4 ). The other pupa (94/101B, Figure 45.3 ) showed markings compatible with female P. caenira ; MJWC associated all four because of the similarities of the pupae and because they were collected on the same palm at the same place at the same time. Nevertheless, the association of the caterpillar although most likely, is not definite.

Leaf shelters. The final instar caterpillar (94/101A) was in a silk lined shelter made from a single leaflet; a 20mm wide notch was cut to the midrib basal to the shelter; the shelter was 60mm long, formed by rolling the leaflet downwards; feeding was distal to the shelter and the leaflet apex had been consumed.

The live pupa (94/101B) was in a shelter formed from two leaflets, the edges held together and strengthened with short bands of silk along the join, which were duplicated along the midrib (probably to roll the leaflet into shape); it was lined with silk and white waxy powder.

Caterpillar. The final instar caterpillar ( Figure 44 ) measured 30mm; head 3.2 x 4.3mm wide x high (n=2); oval, indented at vertex; shiny, rugose; uniform light chestnut brown, except for dark stemmata. T1 pale anteriorly, dark posteriorly; pronotum concolorous in posterior half. Body dull whitish green; dorsal line dark green, bordered by yellow-white subdorsal line; spiracles and T1 legs dark; T2–3 legs and prolegs concolorous; gonads not evident. The caterpillar was noted to flick its frass at least 25cm horizontally. The caterpillar of P. concaenira ( Figure 48 ) is very similar; there are no clear-cut differences, so the possibility of the two species occurring together in MJWC’s Nigeria collection 94/101 cannot be ruled out.

Pupa. Collection 94/101B was a 25mm pupa ( Figure 45.1–3 ); elongate, 4mm wide at front of thorax; short, blunt, dark, bifurcate frontal projection, 1.1mm long, 1.9mm between the divergent tips, a few pale brown setae forward directed on anterior surface; proboscis sheath projects to cremaster tip; head and thorax brown; abdomen yellow brown with slightly darker dorsal line, paler ventrally; spiracles slightly darker than surrounding ground colour. The adult formed up in this pupa, but failed to emerge: spots were visible in the forewing in cell, spaces 2, 3 and 6–8, i.e. compatible with female P. caenira . Pupa 94/101D was already dead, with the head missing (?eaten), but the forewing markings ( Figure 45.4 ) clearly indicating its identity as a male P. caenira .

Natural enemies. Pupa 94/101C was empty and contained a single light grey-brown cocoon in which was a fully formed wasp. The front part of the pupa was missing (similar to 94/101D, Figure 45.4 ) and fitted directly onto the front of the pupa was a mud-dauber wasp cell, which contained an adult wasp and cocoon remains similar to the last. This was opportunistic use of the empty pupa as a suitable niche for a mud cell, but could easily have been misinterpreted as a parasitism event.

Figures

FIGURE 43. Adult male Pteroteinon caenira, Port Harcourt, Nigeria [© D. Motshagen]. Note the similarity to male P. concaenira (Figure 46) in this view.

FIGURE 44. Final instar caterpillar, probably of Pteroteinon caenira, collected 17 Mar 1993 on ornamental palm (?Dypsis lutescens), Ibadan, Nigeria; 30mm; 94/101A. 1, detail of head, anterolateral view; 2, dorsolateral view.

FIGURE 45. Pupae of Pteroteinon caenira, collected 17 Mar 1993 on ornamental palm (?Dypsis lutescens), Ibadan, Nigeria. 1, dorsal view; 25mm; 94/101B; 2, lateral view 25mm; 94/101B; 3, lateral view formed up dead female pupa (mark in space 1B is a pin hole; frontal projection broken off); 94/101B; 4, lateral view formed up dead male pupa (head is missing); 94/101D.

FIGURE 48. Caterpillars of Pteroteinon concaenira, collected on Raphia farinifera, north-west Zambia [TCEC]. 1, young instar, dorsal view; Lisombo Stream, 15 May 2000; 2, final instar, dorsolateral view, Hillwood, 24 Apr 2000; 3, final instar, dorsal view, as #2, 26 Apr 2000.