Axogenesis in the stomatopod crustacean Gonodactylaceus falcatus (Malacostraca)

Abstract

Abstract. The formation of the central nervous system of the stomatopod crustacean Gonodactylaceus falcatus is described by means of antibody stainings against synapsin and α‐tubulin. It is shown that the longitudinal fiber tracts of the ventral nervous system are formed by two centers of origin comprising a number of pioneer neurons, one at the posterior part of the forming brain, the other in the area of the telson anlage at the posteriormost region of the embryo. In addition to the lateral anlagen of the connectives, a median longitudinal nerve is formed beginning in the mandibular segment neuromere. In contrast to those of other segments, the mandibular ganglia are connected by a single commissure. The brain forms a circumoral ring. There is evidence that the deutocerebrum possesses praestomodeal and poststomodeal commissural fibers. The anlage of the nauplius eye reveals a specific pattern of pigment and sensory cells with the two pigment cells expressing synapsin. Clear differences between the expression patterns of synapsin and α‐tubulin recommend the combination of a variety of antibodies to gain a complete picture of embryonic neuroanatomy. Our results show overall similarities to other malacostracan and non‐malacostracan crustaceans. The comparisons with other crustaceans and arthropods indicate homology of crustacean nauplius eyes, a circumoral deutocerebrum, and a more widespread occurrence of posterior pioneer neurons forming the axon scaffold of the ventral central nervous system than previously thought.