EVOLUTION OF THE TELSON NEUROMUSCULATURE IN DECAPOD CRUSTACEA

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Abstract
The neuromusculature in the telsons of 3 macrurans (Pandalus platycerus, Procambarus clarkii, Upogebia pugettensis) and 3 anomurans (Munida quadrispina, Blepharipoda occidentalis, Emerita analoga) are compared to provide a framework for neurophysiological comparisons of their roles in the swimming behaviors of these decapods. The stereotypical arrangement in macruran telsons comprises a group of massive axial muscles and a trio of small appendage muscles. The various arrangements of telson neuromusculature in the anomurans are interpreted in terms of specific modifications of particular macruran features. Homologies among muscle and nerve roots in the telsons of the 6 decapods are identified and homologies among particular axial and appendage motoneurons in the 6th abdominal ganglia are suggested. The appendage neuromusculature in decapod telsons is inferred to be ontophyletically part of the 7th abdominal segment that was present in the ancestors of decapods. These muscles and their motoneurons, like most of the axial neuromusculature in the telson, may be serial homologs of muscles and motoneurons in abdominal segments.