  The results of the longitudinal and Hall magnetoresistivity measurements in
the Shubnikov - de Haas oscillation regime for the HgCdTe/HgTe/HgCdTe
heterostructures with a wide (20.3 nm) HgTe quantum well are presented. An
anomalous phase shift of magneto-oscillations is detected: in the region of
spin-unsplit peaks the longitudinal resistivity maxima are located at even
filling factor numbers in contradiction with a conventional situation in 2D
systems. It is shown that the observed features are associated with the
inverted nature of the spectrum in the investigated quantum well with the
electron-type conduction along the size-quantized subband H1 of HgTe band
{\Gamma}8, for which the spin splitting is comparable to (and even greater
than) the orbital one. The results obtained are compared with the phase shift
effects of both magneto-oscillations and the plateau of the quantum Hall effect
in monolayer graphene.
