Euselasia angulata, Rio Cristalino, Brazil – Tony Hoare
Introduction
The sub-family Euselasiinae is confined entirely to the neotropics. There are 172 known species of which 167 are placed in the genus Euselasia. A few are widespread across Amazonia but most are localised and uncommon. The adults are characterised by having large eyes and small palpi. Most species have rounded wings. The uppersides of males are blackish with patches of metallic orange or blue according to species. Females are dull brown above, with patches of whitish or pale brown.
The undersides are variable – in some species such as gelanor, angulata and brevicauda they are pinkish or dull brown, marked with a thin dark median line. Others e.g. teleclus and praeclara are silvery white, marked with feint dark spots. Another group including euriteus, toppini and orfita are much more strongly marked, with broad white bands on a brown or orange ground colour. Most of the species in this latter group also have a prominent dark spot or ocellus on the outer hindwing.
Most Euselasia species have rounded wings, although the tornus of the hindwing is extended in to a lobe or tail in a few such as thucydides, issoria, euodias and perisama. Only 4 species have angular hindwings – clesa, angulata, eurypus and eubule. There are only two species with sharply angular forewings – the Mexican endemic pontasis, and the Amazonian angulata.
Euselasia angulata is an Amazonian species found in Peru and western Brazil.
Habitats
In common with most other Euselasia species this butterfly inhabits lowland primary rainforests at elevations between about 200-800m.
Lifecycle
I have no information regarding angulata. The lifecycle however is probably similar to that of other Euselasia species : The eggs are frustum-shaped. They are laid singly under leaves of Clusiaceae, Melastomataceae, Sapotaceae or Myrtaceae. The caterpillars are compact in form and covered in tufts of short setae. In several species they are gregarious and move in a processionary manner. Unlike members of the Riodininae the larvae of Euselasiinae are not associated with ants. The pupa is usually positioned on the midrib of the upper surface of a leaf of the foodplant.
Adult behaviour
Euselasia males are noted for their habit of spending most of their lives hiding under leaves. Some species such as gelanor and angulata tend to sit under the leaves of low vegetation, while others such as euriteus and clithra tend to settle higher up, under the leaves of trees at heights of between 2-5 metres. Often males of several Euselasia species will occupy a particular tree but each species will settle at a different height and fly at a different time of the morning.
Although they may appear to be hiding, they are in fact “perching” i.e. waiting to ambush any other Euselasia that flies past. If the ambushed butterfly turns out to be another male a short aerial battle takes place after which the intruding male is usually ousted, and the conquering male returns to sit beneath the leaf where he originally perched. Perching males hold their wings erect, but often with the hindwings very slightly apart, enabling a glimpse of the metallic upperside.
The flight is rapid and erratic. Males are active early in the day, but females fly and oviposit in the afternoon. Both sexes visit flowers and extrafloral nectaries. The butterflies fly throughout the year but are commonest in the late dry season and during drier periods in the rainy season.