Received: 11 September 2019 Revised: 17 November 2019 Accepted: 18 November 2019 DOI: 10.1002/cne.24821 RESEARCH ARTICLE Atlas of the neuromuscular system in the Trachymedusa Aglantha digitale: Insights from the advanced hydrozoan Tigran P. Norekian1,2,3 | Leonid L. Moroz1,4 1Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, Florida Abstract 2Friday Harbor Laboratories, University of Cnidaria is the sister taxon to bilaterian animals, and therefore, represents a key refer- Washington, Friday Harbor, Washington ence lineage to understand early origins and evolution of the neural systems. The 3Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of hydromedusa Aglantha digitale is arguably the best electrophysiologically studied jelly- Sciences, Moscow, Russia fish because of its system of giant axons and unique fast swimming/escape behaviors. 4 Department of Neuroscience and McKnight Here, using a combination of scanning electron microscopy and immunohistochemistry Brain Institute, University of Florida, Gainesville, Florida together with phalloidin labeling, we systematically characterize both neural and mus- cular systems in Aglantha, summarizing and expanding further the previous knowledge Correspondence Leonid L. Moroz, The Whitney Laboratory, on the microscopic neuroanatomy of this crucial reference species. We found that the University of Florida, 9505 Ocean Shore Blvd., majority, if not all (~2,500) neurons, that are labeled by FMRFamide antibody are dif- St. Augustine, FL. Email:
[email protected] ferent from those revealed by anti-α-tubulin immunostaining, making these two neuro- nal markers complementary to each other and, therefore, expanding the diversity of Funding information National Science Foundation, Grant/Award neural elements in Aglantha with two distinct neural subsystems.