Pollen feeding larvae in the presumed predatory syrphine genus Toxomerus Macquart (Diptera, Syrphidae)

Abstract

• The morphology and biology of the larva of Toxomerus apegiensis (Harbach, 1974) are described from Suriname. This larva feeds on pollen of Olyra obliquifolia Steudel, a bambusoid grass (Poaceae) that grows in the understorey of tropical rainforests. The morphology of the larva of Toxomerus politus (Say, 1823), which feeds on pollen of corn, Zea mays, is redescribed. These species are the only known phytophages within the otherwise predatory genus Toxomerus. The cephalopharyngeal skeleton of T. apegiensis shows features that are hypothesized to be modifications towards pollen feeding. These features are absent in the larva of T. politus. Possible evolutionary scenarios of the development of phytophagy within Toxomerus are briefly discussed based on published information on phylogeny of the genus.