Twisting magnetic van der Waals materials provides a compelling approach to generate emergent spin textures through moiré engineering. In this study, we show that a twisted bilayer formed by two antiferromagnetic MnSe monolayers exhibits sublayer-resolved $i$-wave altermagnetic spin splitting. Combining first-principles calculations with a symmetry-constrained continuum theory, we reveal that this spin splitting originates from the rotational misalignment between two hexagonal warping parabolic band dispersions of the monolayer, coupled with sublayer-dependent moiré potentials arising from interfacial charge redistribution. While both AA- and ${\mathrm{AA}}^R$-twisted configurations display similar patterns of altermagnetic splitting, the underlying symmetry mechanisms are fundamentally distinct. In AA-twisted configuration, the effect is driven by locally inversion symmetric moiré potentials in the two layers, whereas in ${\mathrm{AA}}^R$-twisted configuration, it is dictated by a global in-plane $C_2$ symmetry that enforces opposite moiré potential phase relations between the magnetic sublayers. Additionally, we observe that altermagnetic splitting diminishes with decreasing twist angle, indicating a weakening of the rotational misalignment between the warping dispersions and a reduction in moiré momentum scale. Our results establish twisted MnSe as a representative system for layered antiferromagnets with spin-layer coupling and anisotropic warping band edge, offering a versatile platform for engineering twist-induced altermagnetic phases.

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• Altermagnets
• Moire materials
• Twisted bilayers
• Density functional theory