Structure of mandibles in relation to trophic niche differentiation in a tropical millipede community

Abstract

Isotopic composition of nitrogen in 19 species of Diplopoda from a tropical monsoon forest (Cat Tien National Park, southern Vietnam) which supports one of the most diverse millipede faunules globally (no less than 36 species from 17 families and 11 orders) forms a wide continuum of δ15N values ranging from -2.4 to +6.8‰. This suggests a trophic niche differentiation among species. Variation in mouthpart structure could presumably reflect the different foods consumed by species representing at least higher taxa (families and orders). The fine structure of the mandibles in ten sympatric, mostly even syntopic species of Diplopoda does differ considerably between the higher taxa, but neither at the generic nor species level. Neither clear-cut trends in nor evident morphological patterns of, nor significant correlations between the structure of mandibles in Diplopoda species that have different isotopic compositions of nitrogen and presumably exploit different food resources, have been revealed.