To address the phylogenetic relationships of the centipede order Geophilomorpha (more than 1000 species), we have reinterpreted and expanded the knowledge on their morphological disparity, and have doubled the amount of molecular data available. We performed maximum parsimony and maximum likelihood analyses, using 195 phylogenetically informative morphological characters for 80 species, and DNA sequences of 28S, 18S, 16S rRNA and COI for up to 48 species. We found strong support for the monophyly of Geophilomorpha, the basal dichotomy between Adesmata and Placodesmata = Mecistocephalidae, and the basal dichotomy within Adesmata between two clades that are recognized here as superfamilies Himantarioidea and Geophiloidea. With respect to the families currently in use, Himantarioidea comprises three well supported clades corresponding to (i) Oryidae, (ii) Himantariidae, and (iii) Schendylidae s.l. including Ballophilidae; Geophiloidea comprises another three supported clades corresponding to (iv) a new family Zelanophilidae, (v) Gonibregmatidae s.l. including Eriphantidae and Neogeophilidae, and (vi) Geophilidae s.l. including Aphilodontidae, Dignathodontidae, Linotaeniidae, and Macronicophilidae.

Background: The development of specialized appendages involved in sperm transfer in the males of julid millipedes is an extreme case of specialized, complex structures differentiating in a very advanced phase of post-embryonic development. Here, a non-systemic metamorphosis affects the external morphology and the internal anatomy of a trunk double segment only.

BackgroundIn the adult males of helminthomorph millipedes, one or two pairs of legs in the anterior part of the trunk are strongly modified into sexual appendages (gonopods) used for sperm transfer during the copula. Gonopods differentiate in an advanced phase of post-embryonic development, in most cases as replacement for the walking legs of the seventh trunk ring, as these first regress to tiny primordia, to eventually develop into gonopods at a subsequent stadium. These extremely localized but dramatic changes have been described as a non-systemic metamorphosis. In the present study we describe morphological and anatomical changes of trunk ring VII associated with non-systemic metamorphosis in four helminthomorph species.ResultsAs 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.ConclusionsInternal 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.

In most Chilopoda, the walking legs end in a\ud single-tip claw usually accompanied by short accessory\ud spines. Instead, in all species of three small and only distantly\ud related geophilomorph taxa (Diphyonyx, Neogeophilidae,\ud Eucratonyx), the claws of an anterior set of leg\ud pairs are unusually pincer-like. By integrating different\ud microscopic techniques, including confocal laser scanning\ud microscopy, we found that these modified claws are very\ud similar in form, internal structure, and pattern of variation\ud in shape along the trunk in all three taxa: the claws are\ud distinctly swollen and bent, provided with peculiar bulges,\ud and flanked by a conspicuous additional branch, either\ud cylindrical or flattened, which overreaches the tip of the\ud claw; instead, the internal cuticular features are not modified\ud with respect to the condition in the other centipedes,\ud claiming against the possibility of controlled abduction/\ud adduction between claw and branch. Irrespective of the\ud total number of leg pairs (63–129), the claws change\ud gradually from pincer-like to usual shape invariantly in the\ud range spanning between the 34 and the 45% of the total\ud number of leg pairs. Despite these similarities, pincer-like\ud claws originated independently in the three taxa, and by\ud way of fundamentally different changes, either by the\ud dramatic modification of the already existent anterior\ud accessory spine (Diphyonyx, Neogeophilidae) or by the production of a novel cuticular projection (Eucratonyx).\ud Moreover, their shared pattern of variation along the body\ud was most probably constrained by already operating\ud developmental processes controlling the longitudinal patterning\ud of the trunk

The centipedes of the clade Epimorpha change slightly during post-embryonic growth but there is huge variation between species in the maximum body size. New specimens of the rarely collected Neotropical genus Dinogeophilus provide further evidence that this genus comprises the smallest species of the Epimorpha, with a recorded maximum length of 5.5 mm. Up to now Dinogeophilus has been invariantly classified in Geophilidae but different sources of evidence (examination by SEM, cladistic evaluation of morphology, similarity and phylogenetic analysis of molecular data) agree on a very different phylogenetic hypothesis: Dinogeophilus is actually a derived lineage of Schendylidae, only distantly related to Geophilidae, and possibly belong to a mainly Neotropical subgroup of schendylids. A comparison of Dinogeophilus with the most closely related taxa suggests that body miniaturization was accompanied by possibly paedomorphic traits, including lower number of some multiple elements (antennal sensilla, processes on the mouth-parts, coxal organs) and shorter setae. Possibly associated with miniaturization are also a few novel features of Dinogeophilus, among which the unique subterminal denticles of the forcipules, suggesting a possible change in the feeding behaviour.