  We present HST/WFPC2 observations of the dwarf galaxy HIPASS J1321-31. This
unusual galaxy lies in the direction of the Centaurus A group of galaxies, and
has a color-magnitude diagram with a distinctive red plume of luminous stars.
This feature could arise from (a) a red giant branch if the galaxy were much
nearer than previously recognized, (b) a peculiar asymptotic giant branch, or,
(c) an ~1 Gigayear old population of intermediate mass red supergiants, which
we find to be the most likely explanation. However, the lack of equally
luminous blue stars requires that the star formation has dropped substantially
since these stars were formed. Evidently HIPASS J1321-31 experienced an episode
of enhanced star formation rather recently in its star formation history
followed by a period of relative quiescence which has led to the evolution of
the main sequence stars into the red supergiant branch. The stellar populations
in HIPASS J1321-31 reflect a star formation history that is uncommon in star
forming dwarf galaxies. This is the first time such a star formation history
has been noted, although the literature contains a small number of other dwarf
galaxies with similar color-magnitude diagrams. Therefore, HIPASS J1321-31 and
these other galaxies represent a different path of dwarf galaxy evolution that
has not been well-explored and an important probe into how dwarf galaxies
evolve.
