Contour maps of integrated intensity of the MALT90 lines detected towards G1.87−SMM 1. In each panel, the contours are overlaid on the arcsinh-scaled Spitzer 8 μm image (cf. Fig. 1). The contour levels start at 3σ for H¹³CO⁺, SiO, HN¹³C, C₂H, CH₃CN, and ¹³CS. For HNCO(4_0, 4 − 3_0, 3), HCN, HCO⁺, HNC, HC₃N, and N₂H⁺, the contours start at 26σ, 23σ, 20σ, 30σ, 6σ, and 15σ, respectively. In all cases, the contours go in steps of 3σ. The average 1σ value in T_MB units is ~ 0.69 K km s^-1. The red plus sign marks the LABOCA 870 μm peak position of the clump. A scale bar indicating the 1 pc projected length is indicated. The line emission is extended in many cases, and the HCN, HCO⁺, and HNC emissions are well correlated with each other. The N₂H⁺ emission also shows some resemblance to these species. The spatial distributions of HNCO and HC₃N appear to be similar to each other, while weak CH₃CN emission traces reasonably well the 8 μm absorption feature.