Life-History Studies on Mexican Butterflies. IV. the Ecology and Ethology of Anatole rossi, a Myrmecophilous Metalmark (Lepidoptera: Riodinidae)1

Abstract

Anatole rossi Clench, a recently discovered, myrmecophilous metalmark, is known at present only from a small, isolated section of pine forest in the Sierra Tuxtla of southern Veracruz, Mexico. The 3 distinctive structures associated with the myrmecophilous existence of the late-instar larvae are discussed. During the summer months, the formicine ant Componotus abdominalis F. constructs small, shallow pens at the bases of the larval food plant, Croton repens (Euphorbiaceae), and the caterpillars remain in these pens during the daylight hours. At dusk, both ants and caterpillars ascend the plants, where the latter feed during the night but return to the pens before dawn. During the cool winter period, the ants convert the pens into deep tunnels. The last-instar larvae enter a semidiapause and remain rather quiescent for approximately 3 months. Pupation takes place in the pens and tunnels, with the ants remaining in attendance until a few days prior to emergence of the adult butterflies. These subterranean enclosures seem important to the biology of this butterfly, as they are thought to (1) protect the caterpillars from predatory ants, particularly the ponerine Ectatoma tuberculatum (Olivier); (2) carry the species through the winter season, when the adults are killed by even brief cool periods; and (3) protect the caterpillars from the annual fires that are set by the local Indians to clear the pine lands of underbrush. The biology of the adults is discussed, with special emphasis on the effects of fire and man. It is thought that fire (probably man caused) is responsible for the existence of the pine forests. These frequent fires appear to have influenced the growth pattern of the host plant and thus, indirectly, to have affected the evolution of the butterfly.