Natural selection plays a key role in deterministic evolution, as clearly illustrated by adaptive radiations. Unlike most spiders, Dysdera species display a high variability of cheliceral morphologies, which has been suggested to reflect different levels of specialisation to feed on isopods. In this study, we integrate geometric morphometrics and experimental trials with a fully resolved phylogeny of the highly diverse endemic species from the Canary Islands to (1) characterize cheliceral morphologies, (2) unravel their dietary function, (3) examine if they evolved multiple times independently (4) verify whether convergent evolution of morphotypes has occurred and (5) test if specialization could lead to evolutionary irreversibility. We show the existence of nine cheliceral morphotypes and uncovered their significance for trophic ecology. Further, we demonstrate that similar ecomorphs evolved multiple times in the archipelago, providing a novel study system to explain how convergent evolution and irreversibility due to specialization may be combined to shape phenotypic diversification in adaptive radiations.