@article {291, title = {No T{\"o}m{\"o}sv{\'a}ry organ in flat backed millipedes (Diplopoda, Polydesmida)}, journal = {ZooKeys}, volume = {930}, year = {2020}, month = {28/04/2020}, pages = {103-115}, abstract = {

The T\öm\ösv\áry 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 T\öm\ösv\áry organ is commonly used as diagnostic character in taxonomic descriptions and often included in phylogenetic analyses. For the Polydesmida, the largest millipede order, the T\öm\ösv\áry 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 T\öm\ösv\áry 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 T\öm\ösv\áry organ in previous studies, and thus that the T\öm\ösv\áry 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 T\öm\ösv\áry 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 T\öm\ösv\áry 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 T\öm\ösv\áry organ really exists in taxa such as Stemmiulida, and whether the T\öm\ösv\áry organs are homologous across millipedes.

}, keywords = {anatomy, Histology, Micro-Computed Tomography, morphology, tentorium}, issn = {1313-2989}, doi = {10.3897/zookeys.930.48438}, url = {https://zookeys.pensoft.net/article/48438/}, author = {Moritz, Leif and Koch, Markus} }