The ornamental design for a papertowelholder, as shown and described.
FIG. 1 is a front perspective view of a paper towel holder showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is the top plan view thereof; and,
FIG. 7 is the bottom plan view thereof.
The broken lines in the drawings depict portions of the paper towel holder that form no part of the claimed design. In particular, the paper towel holder base and associated rod form no part of the claimed design.