Gall Morphotypes in the Neotropics and the Need to Standardize Them

Abstract

A morphotype can be defined as a specimen that illustrates a morphological variation within a species or, in the case of galls, a characteristic neo-formed plant organ generated by the interaction between a gall-inducing organism and a host plant. Once each gall morphotype is unique and derived from a species-specific interaction, there is a great confidence in using them to identify the different galling systems. In the Neotropics, where the biodiversity is high but somewhat unknown from the taxonomical point of view, the use of morphotypes helps assessing the abundance and richness of galling herbivores. This kind of knowledge would remain inaccessible if its report depended strictly on the taxonomic identification of the involved taxa. An effort on the standardization of the nomenclature used for inventories in the Neotropics revealed that some tridimensional shapes such as the globoid, ellipsoid, and lenticular are quite common, and may be the result of a series of similar events of cell division and expansion. When these morphotypes concomitantly occur on super-hosts of galling herbivores, special attention should be given to the possibility of overestimations, because variables such as the developmental stage of the gall, the age of the host organ by the time of oviposition, as well as morphological variations related to the sex of the inducer may be difficult to be visualized. In specific cases, the phenological and anatomical analyses are crucial to avoid misinterpretations.