Morphology is still an indispensable discipline in zoology: facts and graps from Chilopoda

Abstract

The importance of morphology as a descent discipline of biosciences has been questioned several times in recent years, especially by molecular geneticists. The criticism ranged between an assumed already comprehensive knowledge on animals body plans resulting in no longer need for morphological research and claims that morphological data do not contribute properly to the phylogenetic reconstructions on all systematic levels or to evolutionary research based on the modern synthesis. However, at least the first assumption of an overall knowledge on animal’s outer and inner morphology at present state seems to be unjustified with respect to what is known about Myriapoda. The present paper underlines the necessity and legitimacy to carry out morphological studies in the still widely neglected subgroups of Myriapoda and among them especially in the Chilopoda. Many interesting morphological data on Chilopoda could be gained in recent years, as for instance from epidermal glands and eyes. Gaps of knowledge on the external and internal morphology of centipedes hamper the ability to compare morphological data among the five known chilopod subgroups, to conduct character conceptualisations, to draw scenarios of evolutionary transformations of certain organ systems and/or to use morphological data for reconstructing strongly disputed euarthropod interrelationships. Fundamental gaps in our knowledge on body organisation in Chilopoda are visible on various quality levels. On the one hand, new or improved techniques in analysing or visualising structures (e.g., cLSM,    µ-CT, PC-based 3D-reconstruction) have practically not yet been applied on any centipede. On the other hand, some organs or organ systems, such as the alimentary canal, salivary glands, reproductive systems or cuticular sense organs, are poorly understood or totally unknown with regard to their fine-structural organisation, either concerning all or only some chilopod taxa. In addition, the body organisation of hardly available taxa like Craterostigmomorpha must be widely considered a blank spot on the map of Chilopodology, even on histological level. Fine structural data in chilopods are also limited to adults, developmental studies are generally low in number, technically outdated and do not cover the full systematic range. Examples are given for both current areas of high research activity and also for morphological character complexes yet neglected but indeed worth primary exploration or reinvestigations.