MOUTHPARTS OF 3 COLLEMBOLAN SPECIES - COMPARATIVE MORPHOLOGY

The mouthparts (labrum, mandibles, and maxillae) of three litter-dwell ing collembolan species-Orchesella hexfasciata (Entomobryidae), Isotom a notabilis (Isotomidae), and Sminthurinus henshawi (Sminthuridae)-are described, using both light and scanning electron microscopy. The rig ht molar plate of all three species bears a projection that fits into a corresponding depression on the left molar plate, a previously unnot iced but possibly common and important feature. Based on the free-stan ding nature of molar plate rods, we suggest a brushing rather than a g rinding function. The mouthparts of these species are structurally ver y similar, but differ in size. Size of labrum and mandibles probably d ictates the size of food particles ingested. The rake-like structure o f lamella 1 on the maxillar head of I. notabilis may explain why the g ut contents of this species consist largely of colloidal material.