The ontogenesis of four Lopesia Rübsaamen (Cecidomyiidae) galls on the super-host Mimosa gemmulata Barneby (Fabaceae) reveals peculiar anatomical traits

Abstract

The super-host Mimosa gemmulata has four bivalve-shaped galls induced on the pinna-rachis by congeneric Lopesia spp., which are characterized by four distinct morphologies: the lenticular (LG), the green lanceolate (GLG), the brown lanceolate (BLG), and the globoid (GG) galls. The ontogenesis of these distinct Lopesia galls is related to the capacity of each inducer to differentially manipulate the development of the host plant tissues along its lifespan, resulting in specific gall phenotypes. The ontogenesis of these galls reveals that the differentiation of two types of trichomes is a conservative anatomical trait of M. gemmulata. Nevertheless, under the influence of the four Lopesia spp., the trichome types are altered in size, number of cells, and distribution in the dermal system of each gall. Another conservative trait regarding the vascular system is the collateral arrangement in non-galled and galled conditions, but with an increase in GG vascular elements. The nutritive cells of three out of the four galls originate exclusively from the epidermis, while parenchyma cell lineages participate in the formation of the nutritive tissue of the GG. The intrinsic anatomical features of the four Lopesia galls relate to the site of induction and to the original cell lineages recruited toward the ontogenesis of similar bivalve-shaped morphotypes. However, specific ontogenetic deviations determine each Lopesia gall morphospecies. In contrast, the peculiar structural-functional traits of the GG develop due to its longest lifespan, which consequently leads to the highest stimuli-induced responses in all host plant cell lineages.