MRS continuum-subtracted spectra of C₂H₂ (magenta), HCN (green), H₂O (blue), and CO₂ (brown) emission lines between 13.6 and 15.3 μm from JDISCS sources with submillimeter dust sizes r < 60 au. ALMA images are shown at the right (S. M. Andrews et al. 2018; F. Long et al. 2018, 2019; F. Long et al. 2025, in preparation), in order of submillimeter dust disk size from largest (top left; AS 205N, r ∼ 60 au) to smallest (bottom right; GK Tau, r ∼ 13 au). Slab model fits to the molecular emission lines are overplotted on the spectra, corresponding to the best-fit parameters and upper limits reported in Tables 5, 6, 7, and A1. ¹³C¹²CH₂ emission is also detected in the spectrum of DoAr 33 (M. J. Colmenares et al. 2024).