Cerurina marshalli, (Hampson, 1910) (Hampson, 1910)

Mulvaney, Lydia R. J., 2021, Notes on the life history and taxonomy of Cerurina marshalli (Noctuoidea: Notodontidae: Cerurinae), Metamorphosis 32 (1), pp. 1-12 : 2-3

RESULTS

Behaviour of larvae in the wild

The final instar larvae of C. marshalli described in this paper were found on privately owned land on a plateau about 30 km west of the Luangwa Valley in a relatively unspoiled Miombo woodland and riverine forest (mushitu) habitat with large granite inselbergs and waterfalls supporting a rich diversity of flora and fauna ( Fig. 1 ).

Larvae were found feeding during the day on a single lowlying tree about 1.5 m high on the edge of Miombo woodland. The plant resembled Flacourtia indica (Burm.f.) Merr. (L. Merrett and S.C. Collins, pers. comm.), but had such high levels of herbivory to the leaves that this identification remains tentative.

There were roughly ten larvae on the tree with some individuals dropping to the ground when the tree was approached (behaviour previously observed in C. argentina Schultze, 1916 ). The remaining larvae continued to eat, but aware of a potential threat, began to exhibit characteristic defensive behaviour. When threatened, the larvae raised their heads and hind quarters into a poised defensive position whilst exserting their yellow whip-like flagellae from their anal claspers, flailing them backwards and forwards over their bodies demonstrating the full extent of their bright aposematic colouration in an effort to deter the perceived predator. (Video footage of this remarkable behaviour was captured and is available via the following link: https://youtube.com/watch?v=4VRGUuVt5PA).

When at rest, the larvae were seen extended out along a branch or in a more compact position, sometimes quite still. When eating, they grasped the host plant with their thoracic legs and were observed moving quite quickly around the host plant in the days leading up to pupation.

By the following day, the larvae had almost eaten every leaf on the tree and were also observed chewing the outer layer of bark from the branches while carefully avoiding the sharp tips of the spines.

Description of the early stages of Cerurina marshalli

Four final instar larvae were collected on 16.ii.2019 and pupated within three to five days of collection (18‒ 20.ii.2019). The unhatched cocoon was later dissected to observe the pupa in situ but only a desiccated larva was found. On opening the cocoon, it was observed that the larva had continued to eat the outer layer of bark from the twig inside the cocoon providing it with more woody material for cocoon building (see Discussion section below).

Ovum ( Fig. 2 ). Approximate height 1 mm, diameter 2.3 mm. Colour: dark brown in centre with a translucent ring around outer edge. Shape: hemispherical, mostly smooth with a slightly dimpled surface texture. Description based on dry unfertilised eggs laid inside paper envelope, no information currently known about eggs in nature.

Larva: final-instar ( Figs 3 & 4 ). Length: 40‒50 mm. Colour: head black, body red and black banded. Red colouration appearing brighter in lateral and ventral regions, more faded dorsally. Flagellae bright yellow-orange. Mouthparts: previous research on the mouth parts of this species’ larva described stipital lobes present and with an acute tip, often curving dorsally in front of mandibles, mandibular margin smooth (Godfrey et al., 1989). Thorax: lateral ground colour faded red, three to four globular black markings in upper portion of thorax laterally, more reduced globular markings in lower portion. A ‘bell- curve’ shaped dorsal plate present, directly behind head, shiny-black, smooth. Thoracic legs: shiny black. Abdomen: black parallel sided bands running around the entire circumference of the larva, separated by faded red intersegmental sections. Pro-legs: four pairs of non-sclerotized pro-legs present, black, apically rounded. Spiracles black. Larvae bearing one pair of modified anal claspers, shiny black, curved slightly towards body, bearing numerous short thorn-like spines. Flagellae: one pair of bright yellow-orange extendable flagellae, exuded during defensive display.

Pupae and cocoons ( Fig. 5 ). Pupation occurs inside hardened cocoons. Information about colour and appearance of pupa not currently known. Cocoon oval; height approximately 10 mm, width 12 mm, length 20‒ 30 mm. Formed on surface of branch using fragments of chewed bark spun into cocoon during construction, resulting in cocoons being robust and camouflaged in appearance, resembling the colour and texture of bark.

Adult moths

Two adult moths emerged within a day of each other (15– 16.iii.2019), both female (Figs 6 & 7). The third adult failed to eclose and the fourth larva escaped before pupation.

Figures

Figure 1 – Habitat at Mutinondo wilderness area in Zambia showing vast Miombo woodland and granite inselberg habitats.

Figure 2 – Cerurina marshalli ovum: left – dorsal view; right – lateral view. Scale bar = 1 mm.

Figure 3 – Final instar larvae of C. marshalli on host plant.

Figure 4 - Final instar larva of C. marshalli with its flagellae exserted.

Figure 5 – Cocoon of Cerurina marshalli – lateral view.