Acceso en línea sin restricciones

The mandibular edge of males and females of several American species of the cyclopoid genus Mesocyclops was examined. The general structure, arrangement, and size of teeth was assessed for each species and shown to be variable among them. We used a modified version of a previous index, the Gnathal Index (GI) plus the Mandibular Size Index (MSI), and the Mandibular Power Index (MPI) which, together are expected to 1) provide a quantitative measure of morphologic variation amongst species and 2) suggest the feeding habits of these species. All species showed different values in terms of teeth number, size, and arrangement, as indicated by results of these indices. Known predatory species (i.e., M. edax, M. longisetus, and M. aspericornis) showed high values of MSI and MPI. The MSI values were positively correlated to the total body length. Our data suggest a predatory capability for these two species. Mesocyclops yutsil, M. reidae, and M. chaci had the lowest MPI and MSI values; they represent a group that probably are detritivores. The remaining species, all with lower MPI values, are probably omnivores. For the species examined here, most males are smaller than females but their mandibles tend to be similar in relative size and structure. Experimental observations support our conclusions about the predatory forms. Feeding experiments are needed to determine the limits of these indices for most species in the second and third groups. Inglés