Small field neuron of the central complex with dendritic arbors in a slice (wedge) of the ellipsoid body and axonal arborizations in a glomerulus of the protocerebral bridge and in the gall (Hanesch et al., 1989; Lin et al., 2013; Wolff et al., 2015). It receives input from several types of ring neuron (Hulse et al., 2021).
R-neuron that passes through the ellipsoid body canal, entering the neuropil from the posterior part of the canal and projecting outwards and slightly anteriorly (Omoto et al., 2018). Its terminals define the boundary between the inner and outer posterior layers of the ellipsoid body (Omoto et al., 2018). Unlike most other R-neurons, its dendritic branches are found on the lateral surface of the lateral accessory lobe, rather than the bulb (Omoto et al., 2018).
R-neuron that enters the ellipsoid body from the central canal, projects centrifugally, and has axon terminals throughout the outer central domain of the ellipsoid body (Hanesch et al., 1989; Young and Armstrong, 2010; Omoto et al., 2018). It does not arborize in a narrow region on the outermost periphery of this domain, which is where R4d terminals are found (Omoto et al., 2018). Proximal dendrites of R2 form club-shaped glomerular endings in the medial two-thirds of the superior bulb (Omoto et al., 2018).
R-neuron that has centrifugal projections into the ellipsoid body; there are several subclasses, but they all arborize more proximally than R2 and more anteriorly than R1 (Omoto et al., 2018).
R-neuron that arborizes only in the outer central domain of the ellipsoid body (Renn et al., 1999; Omoto et al., 2018). Arborizing branches enter the ellipsoid body from the periphery and extend inwards, centripetally (Hanesch et al., 1989; Omoto et al., 2018).