Subfamily Sagrinae Leach, 1815

Sagrinae

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Subfamily Sagrinae Leach, 1815

Sagrinae Leach, W.E. 1815. Entomology. pp. 57-172 in Brewster (ed.). The Edinburgh Encyclopedia. Edinburgh : William Blackburn Vol. 9(1) 764 pp. [reprint 1830] [113].

Introduction

The subfamily Sagrinae is small, with 12 genera and 74 species worldwide, and confined to the Southern Hemisphere (Crowson 1981). The Australian fauna is disproportionately large, with 10 genera and 33 species (Monros 1960). Within Australia, the Sagrinae are most diverse in the arid and semi-arid zones, but also occur in heathland and woodland almost throughout the continent (absent from Tasmania).

The Sagrinae once included all plesiomorphic Chrysomelidae. The group was rearranged to its present form by Monros (1960), who indicated a sister-group relationship with the pea-weevils, Bruchinae. This relationship has been confirmed by morphological (Reid 1995, 2000) and molecular studies (Farrell & Sequiera 2004). The world fauna has been revised twice but the two published keys (Crowson 1946; Monros 1960) disagree considerably with each other. These authors also disagree over species synonymy, although only Monros presented keys to all species.

Adults of Sagrinae are large and conspicuous (Megamerus species up to 3 cm), but rare, most specimens having been collected at light. Sagra species are brilliantly coloured.

The biology of Sagrinae is poorly known. Adults feed on pollen, primarily on myrtaceous trees and shrubs in Australia (Matthews & Reid 2002). Eggs of an unknown Australian genus have been found enclosed in an earthen case on a plant stem. First instars are c-shaped grubs with small legs and deep-set head capsules, typical of wood-boring beetle larvae (Reid 1995). Larvae of Sagra are stem miners, causing large stem galls in saplings (Maulik 1941). The larval hosts of Sagra are varied, but include commercially important timber and shade trees (Maulik 1941). Pupation of Sagra is in the larval burrow, but a pupa of the Australian genus Polyoptilus has been collected from an earthen cell in soil.

Diagnosis

After Reid 2000. Adult: head prognathous; face with deep grooves between antennal insertions; inner margin of eyes excavate; ventral surface without dense adpressed setae (plastron); hind femur relatively enlarged; tegmen with dorsal cap.
Larva: white, c-shaped, living inside stems; head capsule elongate, but deeply inserted into prothorax; labial palpi 2-segmented; legs with distinct pretarsus; first instar without prothoracic ridge.