Systematics of scratch worms

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The classic system of scratch worms or scratches (Acanthocephala) is based primarily on morphological features of the anatomy of sexually mature animals and the larval stages as well as on features of the eggshells and ecology (host types, etc.). A number of common features, so-called apomorphies , can be named as indicators for the monophyly of the scratchworms . These include, among other things, the very specific epidermis with the lacunae system for feeding the animals, which only exists in the scratching worms, the evertable trunk with the hooks, the ligament sacs and the very special design of the female genital organs with the specialized uterine bell .

The scratchworms contain three taxa classified as classes, which differ mainly in their size and host range as well as some morphological features. The design of the ligament sac, the position of the main ducts of the lacunae system and the number of cement glands in males play an important role; the structure of the eggshells, the characteristics of the life cycle (intermediate and final hosts) and molecular biological characteristics are also used as a basis for the classification . All of these characteristics suggest that the three classes are monophyletic groups :

The classic system of scratch worms

Pomphorhynchus in the rectum of a blue fish ( Pomatomus saltatrix )

This system essentially follows the representation of the Integrated Taxonomic Information System

supporting documents

  1. ↑ Thomas J. Near: Acanthocephalan Phylogeny and the Evolution of Parasitism. Integrative and Comparative Biology 42, 2002; Pages 668-677. ( Full text ; PDF; 236 kB)
  2. ^ Phylogenetic Relationships of the Acanthocephala Inferred from 18S Ribosomal DNA Sequences. Molecular Phylogenetics and Evolution 10 (3), 1998; Pages 287-298. ( Full text )
  3. ↑ see Acanthocephala and subordinate taxa