(a) Coexpression of opsin and VGAT reporter constructs in the ocellus (white and orange arrowheads). Insets show expression of Opsin-1 and VGAT individually. (b) Expression of VGLUT and VGAT in the brain vesicle and epidermis by in situ hybridization. VGAT was observed in an anterior (white arrowhead) and posterior (orange arrowhead) domain of the ocellus. Blue arrowhead indicates VGLUT expression in the ocellus, and red arrowheads indicate VGLUT-expressing epidermal sensory neurons. (c) Posterior VGAT-expression in the ocellus consists of two cells (orange arrowheads), one exclusively expressing VGAT, and one coexpressing VGAT and VGLUT. Two cells in the anterior exclusively express VGAT (white arrowheads). Nuclei are shown as red spheres. Asterixis indicate overlap of VGAT and VGLUT. (d) Neurotransmitter predictions color-coded on a schematic diagram of the ocellus photoreceptors. Lines between photoreceptors indicate chemical synaptic connections taken from Satoh (1994), with red lines indicating projections to the relay neurons. (e) Heat map of neurotransmitter predictions from registration for photoreceptor group I (cells 01–23). Scale assigns color to proportion of iterations predicting VGAT or VGLUT within a particular cell. (f) Confusion matrix of registration of photoreceptor group I cells (cells 01–23). High values (light colors) in the diagonal indicate higher confidence. Abbreviations: dor., dorsal; vent., ventral; ant., anterior; post., posterior; em., eminens cell; RN, relay neuron; AC, antenna cells; pr-AMG RN, photoreceptor ascending motor ganglion relay neuron; prRN, photoreceptor relay neuron; VGAT, vesicular GABA transporter; VGLUT, vesicular glutamate transporter; PR-I, photoreceptor group I (01–23).