Project 3582: L. Moritz, M. Koch. 2020. No Tömösváry organ in flat backed millipedes (Diplopoda, Polydesmida). ZooKeys. 930:103-115.
Specimen: Polydesmus angustus (Latzel, 1884) (Histostack)
View: Histological crossection


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.

Read the article »

Article DOI: 10.3897/zookeys.930.48438

Project DOI: 10.7934/P3582,
This project contains
  • 6 Media
  • 4 Taxa
  • 6 Specimens
Total size of project's media files: 7.14M

Download Project SDD File
Currently Viewing:
MorphoBank Project 3582

    Authors' Institutions

    • Rheinische Friedrich-Wilhelms-Universität Bonn (University of Bonn)

    • Zoologisches Forschungsmuseum Alexander Koenig

    • Senckenberg Gesellschaft für Naturforschung


    member name taxa specimens media media
    Leif Moritz
    Project Administrator

    Project has no matrices defined.

    Project views

    type number of views Individual items viewed (where applicable)
    Total project views7456
    Project overview683
    Media views2503Media search (1226 views); M684040 (206 views); M685199 (206 views); M685200 (226 views); M686922 (228 views); M686924 (210 views); M686923 (201 views);
    Views for media list686
    Specimen list2049
    Taxon list1283
    Documents list1

    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project117
    Media downloads1M684040 (1 download);
    Project downloads116