I feel like this is the evolution of my previously featured puzzle Pentominophibian. More interesting and a (slightly) more concise ruleset. Enjoy!

Rules:

• Normal sudoku rules apply.

• Draw a single loop of orthogonally connected cells into the grid. The loop does not split, move diagonally, or cross over itself. However, it may touch itself both orthogonally or diagonally. Divide the loop into contiguous groups of 5 cells, i.e., pentominoes, such that every cell along the loop belongs to exactly one pentomino. Each provided dot is the center-point of a pentomino (i.e., the third of five cells along that pentominoes portion of the loop). No two pentominoes on the loop are allowed to be of identical shape. Two pentominoes are considered identical if they can be mapped into each other by pure rotation (for example L and ꓶ), while two pentominoes are considered different if additionally a reflection would be needed (for example L and ⅃) or if they cannot be mapped into each other at all (for example L and I).

• Black dots are center-points to pentominoes that cannot create a different pentomino by reflection (for example the I or U pentomino).

• Pairs of dots that are the same colour (greens, yellows, blues, and reds) are center-points of pentominoes that are reflections of one another (but may still be rotated differently).

• Digits outside the grid are Loopy X-sums. They indicate the sum of digits on the loop within the first X digits in the row, column, or diagonal, where X is the first digit in the direction of the clue.

Below is the solution to a mini-example of marrow that can be played here.