Low temperature scanning electron microscopy (LT-SEM) has revealed anatomical details suggesting that Osperalycus and Gordialycus (Acariformes: Nematalycidae) have an unusual feeding apparatus that is hypothesized to be specialized for feeding on the fluid contents of small microorganisms (diameter<5 μm). Both mite genera have a feeding strategy that appears to involve picking up small microorganisms and placing them onto the subcapitulum for puncturing. However, they have slightly different variants of the same basic rupturing mechanism. Whereas Gordialycus has evolved expansive and convergent rutella to hold the microorganisms in place while pushing chelicerae into them, Osperalycus has evolved a pouch into which a microorganism is inserted. The rutella reinforce this pouch while the chelicerae break up the microorganism. Both types of mouthpart apparatus seem to be adapted to minimize waste, an appropriate specialization given the organically impoverished habitats in which these mites live.
Keywords: Gnathosoma; Gordialycus; LT-SEM; Microorganism; Nematalycidae; Osperalycus; Rutellum.
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