The ornamental design for a decorativebookwormhead for an interconnectable seating array, as shown and described.
FIG. 1 is a front view of my design.
FIG. 2 is a rear view of my design.
FIG. 3 is a top view of my design.
FIG. 4 is a bottom view of my design. The broken lines in FIG. 4 are included for the purpose of illustrating a portion of the environmental structure that forms no part of the claimed design.