Sternites and spiracles - the unclear homology of ventral sclerites in the basal millipede order Glomeridesmida (Myriapoda, Diplopoda)

Description of the first species of Glomeridesmida from Thailand (Diplopoda, Glomeridesmida, Glomeridesmidae)

With three genera and 35 previously known species from India, SE Asia, Central and South America, Glomeridesmida are one of the least diverse Diplopoda groups. Here we describe Glomeridesmussiamensissp. nov., the first species of the order Glomeridesmida from Thailand. The geographically nearest confamiliar species have been described from southern India, Sumatra and Java. The species is described combining photographs, light- and scanning electron microscopy of mature and younger males, females and juveniles. Several characters are illustrated for the first time for an Asian representative of the family Glomeridesmidae. In addition to the type locality of G.siamensissp. nov. from Krabi province, locality data of unidentified Glomeridesmus from Thailand are also given. These data are providing further evidence that the Glomeridesmida are not uncommon, but overlooked as they are small and difficult to collect. The unusual telopods and other morphological characters of G.siamensissp. nov. differ considerably from the few Glomeridesmus males described from Central and South America as well as from India, but the unclear status of two generic names available for species from Indonesia prevents us from adding another generic name to this small and understudied order.

The tracheal system of scutigeromorph centipedes and the evolution of respiratory systems of myriapods

The tracheal system of scutigeromorph centipedes (Chilopoda) is special, as it consists of dorsally arranged unpaired spiracles. In this study, we investigate the tracheal systems of five different scutigeromorph species. They are strikingly similar to each other but depict unique characters compared to the tracheal systems of pleurostigmophoran centipedes, which has engendered an ongoing debate over a single versus independent origin of tracheal systems in Chilopoda. Up to now, only the respiratory system of Scutigera coleoptrata was investigated intensively using LM-, TEM-, and SEM-techniques. We supplement this with data for species from all three families of Scutigeromorpha. These reveal interspecific differences in atrial width and the shape and branching pattern of the tracheal tubules. Further, we investigated the tracheal system of Scutigera coleoptrata with three additional techniques: light sheet microscopy, microCT and synchrotron radiation based microCT analysis. This set of techniques allows a comparison between fresh versus fixed and dried material. The question of a unique vs. multiple origin of tracheal systems in centipedes and in Myriapoda as a whole is discussed with regard to their structural similarities and differences and the presence of hemocyanin as an oxygen carrier. We used morphological and molecular data and the fossil record to evaluate the alternative hypotheses.

A first phylogenetic analysis of the pill millipedes of the order Glomerida, with a special assessment of mandible characters (Myriapoda, Diplopoda, Pentazonia)

The pill millipedes of the order Glomerida are a moderately diverse group with a classical Holarctic distribution pattern. Their classification is based on a typological system utilizing mainly a single character complex, the male telopods. In order to infer the apomorphies of the Glomerida, to elucidate its position in the Pentazonia, and to test the monophyly of its families and subfamilies, we conduct the first phylogenetic analysis of the order. To provide additional characters, we comparatively analyze the mandible using scanning electron microscopy. The final character matrix consists of 69 characters (11 mandible characters) and incorporates 22 species from 20 of the 34 pill millipede genera, representing all families and subfamilies, except the monotypic Mauriesiinae. Two species from each of the two other Pentazonian orders Sphaerotheriida and Glomeridesmida, as well as two Spirobolida, are included as outgroup taxa. The Glomerida are recovered as monophyletic and are supported by five apomorphies. Within the Pentazonia, the Glomeridesmida are recovered as the sister group to the classical Oniscomorpha (Sphaerotheriida + Glomerida) with weak support. The analysis provides little resolution within the Glomerida, resulting in numerous polytomies. Further morphological characters and/or the addition of molecular analyses are needed to produce a robust phylogenetic classification of the Glomerida.

A general methodology for collecting and preserving xystodesmid and other large millipedes for biodiversity research

Background

With an estimated 80% of species remaining undescribed (but see Brewer et al. 2012), millipede taxonomy offers the opportunity to discover new species and explore biodiversity. The lack of basic alpha taxonomic information regarding millipedes belies their significant ecological role and potential as premier models in ecological and evolutionary studies. The group possesses many fascinating biological properties (e.g., bioluminescence, mimicry, and complex chemical secretions) that have been the focus of several recent studies and are emerging avenues of future investigation.

New information

Here we summarize a methodology for large-bodied millipede collection, curation, and preservation for genetic analyses with the hope that sharing these techniques will stimulate interest in these charismatic detritivores.

Revival of forgotten characters and modern imaging techniques help to produce a robust phylogeny of the Diplopoda (Arthropoda, Myriapoda)

The external and internal anatomy of millipedes (Diplopoda) is poorly known compared to some of the other myriapod and arthropod groups. Due to both language barriers, which hindered the assessment of the character-rich older literature, and non-phylogenetic thinking, our knowledge of morphological characters useful for phylogenetic work diminished over the last decades. Here, a new character matrix with 64 characters, mainly derived from old literature data, is used to reconstruct a phylogeny of Diplopoda. As a tool to further our knowledge about the morphology of the different millipede orders, we show how micro-computer tomography (μCT) can be used to assess and illustrate specific parts of the Platydesmida. With the advent of μCT it is now possible to analyse many taxa and characters in a comparatively short time. A focus is put on potential phylogenetically useful characters. Our results support a Verhoeffian classification of the Diplopoda: Polyxenida + Chilognatha. Pentazonia are the sistergroup to the Helminthomorpha. Colobognatha form the sistergroup to Eugnatha, the latter split into monophyletic Juliformia and Polydesmida + Nematophora.