Voronoi tessellation analysis of the area around the X-ray identified cluster structure at 0.35 <z_phot< 0.50 (lines). Galaxies associated with overdense structures identified via our VTA analysis (see text for details) are shown as black dots. A projected scale of 1 Mpc is indicated in the top left corner. The X-ray identified clusters are marked with thick black circles, and VTA identified overdense structures are marked with thin grey circles, and labelled in the plot. Galaxies within these regions were sampled to statistically estimate the properties of clusters and overdense structures. (See Table 3 for details.)