Same as Fig. 4, but showing only the sources from the Serpens South cluster forming clump. Triangles show the locations of the MAMBO protostars (green triangles are Class 0 and red triangles are Class I protostars, while black triangles represent the border-line objects). Red circles show the locations of the Class I protostars detected by Spitzer  and without MAMBO detection. The Class I sources without any MAMBO counterpart are indicated as upper-limit values for M_env, around the detection limit of 2.5 × 10^-2M_⊙. The green double arrow along the M_env axis shows the range of masses for the prestellar cores detected by Herschel, based on a preliminary analysis of the Gould Belt survey data, which are 85% complete down to 0.3M_⊙ in this region (Könyves et al. 2010). The respective locations of the prestellar cores, Class 0 and Class I protostars in the Serpens South protocluster are roughly consistent with what is expected from a single population of objects evolving along the model evolutionary tracks shown in blue.