00606nas a2200193 4500008004100000022002200041245003300063210003100096260002600127300001200153490000600165520005900171100001700230700002400247700001700271700002100288700002400309856007900333 2011 eng d a978-90-04-15611-100aChilopoda - Digestive system0 aChilopoda Digestive system aLeiden, BostonbBrill a121-1360 v13 a

Publication date: 21/03/2011

1 aKoch, Markus1 aMüller, Carsten, H1 aHilken, Gero1 aRosenberg, Jörg1 aMinelli, Alessandro uhttps://brill.com/display/book/edcoll/9789004188266/B9789004188266_007.xml02819nas a2200205 4500008004100000245016200041210006900203300001000272490000800282520204400290653002202334653002102356653001302377653002302390653001402413100001702427700002002444700001702464856013202481 2018 eng d00aAn apparently non-swinging tentorium in the Diplopoda (Myriapoda): comparative morphology of the tentorial complex in giant pill-millipedes (Sphaerotheriida)0 aapparently nonswinging tentorium in the Diplopoda Myriapoda comp a77-910 v7413 a

The presence of a swinging tentorium is a key apomorphy of Myriapoda, but this character has been studied in detail in only few species. Here the tentorium, i.e., the peristomatic skeleton of the preoral chamber, is comparatively studied in three species of the millipede order Sphaerotheriida Brandt, 1833. Since dissections of the fragile tentorial components proved to be difficult, despite the large head size, they were analysed mainly in situ via micro-computed tomography. Our results confirm previous observations of large differences in the tentorial construction in the giant pill-millipedes compared to chilognathan diplopods. The tentorium of Sphaerotheriida consists of a curved, plate-like epipharyngeal bar with distal projections, an elongate and thin hypopharyngeal bar, and a plate-like triangular posterior process; a transverse bar is absent. Only seven muscles attach at the tentorium in giant pill-millipedes, including two antennal muscles and two muscles of the gnathochilarium. Within the order Sphaerotheriida, the composition of the tentorium and its muscular equipment seems to be conserved, except for some variability in the shape of the epipharyngeal bar. As the transverse bar has been considered essential for the mobility of the tentorium in myriapods, its absence in Sphaerotheriida may indicate that their tentorium is not capable of performing a swing. Loss of tentorial mobility may also pertain to the order Glomerida Brandt, 1833, inferred here from the absence of a posterior process. An apparently immobile tentorium in Glomerida and Sphaerotheriida can straightforwardly be correlated with transformations of the head related to their ability of volvation. The different transformations of the tentorium, here hypothesised to cause immobility, may support current assumptions that the ability of volvation evolved convergently in Glomerida and Sphaerotheriida. This conclusion, however, still requires more detailed studies of the head anatomy in Glomerida and Glomeridesmida Cook, 1895.

10a3D-reconstruction10aArthrosphaeridae10amicro-CT10aswinging tentorium10avolvation1 aMoritz, Leif1 aWesener, Thomas1 aKoch, Markus uhttps://myriatrix.myspecies.info/content/apparently-non-swinging-tentorium-diplopoda-myriapoda-comparative-morphology-tentorial02637nas a2200265 4500008004100000022001400041245011400055210006900169260001500238300001600253490000800269520179300277653001502070653001902085653002102104653001402125653002302139100002702162700003102189700001902220700003202239700002402271700001702295856005902312 2020 eng d a0027-842400aAquatic stem group myriapods close a gap between molecular divergence dates and the terrestrial fossil record0 aAquatic stem group myriapods close a gap between molecular diver c06/04/2020 a8966 - 89720 v1173 a

Identifying marine or freshwater fossils that belong to the stem groups of the major terrestrial arthropod radiations is a longstanding challenge. Molecular dating and fossils of their pancrustacean sister group predict that myriapods originated in the Cambrian, much earlier than their oldest known fossils, but uncertainty about stem group Myriapoda confounds efforts to resolve the timing of the group’s terrestrialization. Among a small set of candidates for membership in the stem group of Myriapoda, the Cambrian to Triassic euthycarcinoids have repeatedly been singled out. The only known Devonian euthycarcinoid, Heterocrania rhyniensis from the Rhynie and Windyfield cherts hot spring complex in Scotland, reveals details of head structures that constrain the evolutionary position of euthycarcinoids. The head capsule houses an anterior cuticular tentorium, a feature uniquely shared by myriapods and hexapods. Confocal microscopy recovers myriapod-like characters of the preoral chamber, such as a prominent hypopharynx supported by tentorial bars and superlinguae between the mandibles and hypopharynx, reinforcing an alliance between euthycarcinoids and myriapods recovered in recent phylogenetic analysis. The Cambrian occurrence of the earliest euthycarcinoids supplies the oldest compelling evidence for an aquatic stem group for either Myriapoda or Hexapoda, previously a lacuna in the body fossil record of these otherwise terrestrial lineages until the Silurian and Devonian, respectively. The trace fossil record of euthycarcinoids in the Cambrian and Ordovician reveals amphibious locomotion in tidal environments and fills a gap between molecular estimates for myriapod origins in the Cambrian and a post-Ordovician crown group fossil record.

10aArthropoda10aeuthycarcinoid10amolecular dating10aMyriapoda10aTerrestrialization1 aEdgecombe, Gregory, D.1 aStrullu-Derrien, Christine1 aGóral, Tomasz1 aHetherington, Alexander, J.1 aThompson, Christine1 aKoch, Markus uhttp://www.pnas.org/lookup/doi/10.1073/pnas.192073311703249nas a2200217 4500008004100000022001400041245007700055210007200132260001500204300001200219490000800231520262600239653001202865653001402877653003002891653001502921653001402936100001702950700001702967856004702984 2020 eng d a1313-298900aNo Tömösváry organ in flat backed millipedes (Diplopoda, Polydesmida)0 aNo Tömösváry organ in flat backed millipedes Diplopoda Polydesmi c28/04/2020 a103-1150 v9303 a

The Tömösváry organ is a sensory structure of the head in myriapods and some other terrestrial arthropods. Due to its variable shape, size, and position in millipedes (Diplopoda) the Tömösváry organ is commonly used as diagnostic character in taxonomic descriptions and often included in phylogenetic analyses. For the Polydesmida, the largest millipede order, the Tömösváry organ is inconsistently stated as being either absent or present as a pear-shaped pit covered by a membrane or cuticular disc. In order to resolve this inconsistency, we investigated the morphology of the presumable Tömösváry organ in four polydesmidan species based on paraffin-histology, semi-thin sections and micro-computed tomography. Our results unambiguously favor the view that the articulation of the cephalic tentorium with the head capsule was misidentified as the Tömösváry organ in previous studies, and thus that the Tömösváry organ indeed is absent in the Polydesmida. The pear-shaped pit proved to represent the distal roundish expansion of the incisura lateralis, to which – similarly as in julidan millipedes – the tentorial transverse bar is articulated. The absence of the Tömösváry organ in the Polydesmida does not affect the topology of the interrelationships among the millipede orders retrieved in previous cladistic analyses based on morphology. As a character shared by Colobognatha and Juliformia, however, absence of a Tömösváry organ in Polydesmida favors the optimization of its presence in nematophoran millipedes as a reversal. Further studies are needed to clarify whether among chilognathan millipedes a Tömösváry organ really exists in taxa such as Stemmiulida, and whether the Tömösváry organs are homologous across millipedes.

 

10aanatomy10aHistology10aMicro-Computed Tomography10amorphology10atentorium1 aMoritz, Leif1 aKoch, Markus uhttps://zookeys.pensoft.net/article/48438/