Mandibular morphology and dietary preferences in two pygmy molecrickets of the genus Xya (Orthoptera: Tridactylidae)

Pygmy mole crickets (Tridactylidae) are an interesting but little-known group of Orthoptera; their food biology and dietary preferences have not been adequately studied. Our study focused on the diet composition and associated functional morphology of the mandibles in two European species: Xya pfaendleri Harz, 1970 and X. variegata (Latreille, 1809). Based on postmortem gut content analyses, the studied species feed mainly on detritus (decaying organic particles), representing 91% and 97% of the diet in X. pfaendleriand X. variegata, respectively. The mandibular structures are associated with the processing of such food. The incisor area is equipped with three robust and sharp teeth, and the molar area consists of a small molar ridge forming a trituration area with parallel molar slats. The size of the molar ridge is determined by sex and the side (left/right) of the mandibles: females have larger molar ridges than males and left molar ridges are larger than the right. Food preferences as well as measured parameters of the mandibles were similar in both studied species due to the similar pattern of their biology. The narrow food niche indicates a low diversity of consumed food and uniformity of food intake.

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