Two new troglobitic species of the freshwater crab genus Sundathelphusa (Parathelphusidae), S. waray, n. sp., and S. lobo, n. sp., are described from two caves in Samar, Philippines. This discovery brings the number of cavernicolous species of Sundathelphusa in the Philippines to nine. It is the first record of freshwater and true cavernicolous crab species from Samar. These two new species are morphologically closely related to S. cavernicola Takeda, 1983 and S. hades Takeda and Ng, 2001, but differ distinctly in the shape of carapace and the presence of long corneous spines in the dactyli. The new species are characterized by the non-pigmented body, greatly reduced eyes and long ambulatory legs that are associated with previously known troglobitic crabs. The presence of corneous spines on the distal two segments of the ambulatory legs is suggested as troglomorphic adaptation to subterranean habitat. A key to the cavernicolous freshwater crabs of the Philippines is also provided.