Schematic diagram of the main neutral (black) and ionic (red or green for dissociative recombination, DR) pathways leading to the formation of aromatic species. Most DRs, typically represent the major destruction pathways for ions, are not shown because they generally do not lead to the formation of aromatic cycles. Arrow widths are proportional to the integrated total production rates. Radiative association reactions are indicated by dashed lines. Radicals are shown in boxes, and closed-shell species in circles. Observed species in TMC-1 (C₃H₃, l-C₃H₃⁺, C₆H₅CN, C₆H₅C₂H, etc.) are highlighted in bold.