%0 Journal Article
%T Structural aspects of leg-to-gonopod metamorphosis in male helminthomorph millipedes (Diplopoda)
%A Leandro Drago
%A Giuseppe Fusco
%A Elena Garollo
%A Alessandro Minelli
%J Frontiers in Zoology
%D 2011
%I BioMed Central
%R 10.1186/1742-9994-8-19
%X As documented here for the first time by means of traditional histology methods and new techniques based on confocal laser scanning microscopy, the external modifications caused by non-systemic metamorphosis are associated to a huge rearrangement of internal anatomy, mostly due to the development of gonopod apodemes and extrinsic muscles.Internal changes in the seventh trunk ring, locally leading to the dorsal displacement of the ventral nerve cord and the digestive tract, are modulated in a taxon-specific manner, and are very conspicuous in the blaniulids Nopoiulus kochii and Blaniulus guttulatus, with likely major functional consequences.The trunk of millipedes (Diplopoda, Figure 1) articulates into a series of segmental units to most of which (diplosegments) correspond two pairs of walking legs, while the first four or five post-cephalic units exhibit a different correspondence between dorsal and ventral structures, the most common arrangement being a legless collum, followed by three haplosegments with one leg pair each. Because of the independent segmentation of dorsal and ventral structures during millipede embryogenesis [1], segmental units we will refer to here are exclusively intended as descriptive modules, thus disregarding problems of homology stemming from their developmental origin [2,3].The tiny pin-cushion millipedes, the Penicillata (= Polyxenida), have no specialized sexual appendages, while in the sister clade, the Chilognatha, specialized sexual appendages are found in adult males. The Chilognatha include two major clades, the Pentazonia, i.e. the pill millipedes (Glomerida) with their closest relatives (Glomeridesmida and Sphaerotheriida), and the Helminthomorpha, which includes the vast majority of the Diplopoda, e.g. the widespread juloid and polydesmoid forms. In the adult males of Pentazonia the last pair of appendages are replaced by a pair of articulated pincers (the telopods). In the adult males of the Helminthomorpha, one or two pairs of
%K post-embryonic development
%K segment differentiation
%K sexual appendages
%U http://www.frontiersinzoology.com/content/8/1/19