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We present HI spectral line and optical broadband images of the nearby lowsurface brightness dwarf galaxy KDG215. The HI images, acquired with the KarlG. Jansky Very Large Array (VLA), reveal a dispersion dominated ISM with onlyweak signatures of coherent rotation. The HI gas reaches a peak mass surfacedensity of 6 M$_{\odot}$ pc$^{-2}$ at the location of the peak surfacebrightness in the optical and the UV. Although KDG215 is gas-rich, theH$\alpha$ non-detection implies a very low current massive star formation rate.In order to investigate the recent evolution of this system, we have derivedthe recent and lifetime star formation histories from archival Hubble SpaceTelescope images. The recent star formation history shows a peak star formationrate $\sim$1 Gyr ago, followed by a decreasing star formation rate to thepresent day quiescent state. The cumulative star formation history indicatesthat a significant fraction of the stellar mass assembly in KDG215 has occurredwithin the last 1.25 Gyr. KDG215 is one of only a few known galaxies whichdemonstrates such a delayed star formation history. While the ancient stellarpopulation (predominantly red giants) is prominent, the look-back time by which50% of the mass of all stars ever formed had been created is among the youngestof any known galaxy.

Delayed Stellar Mass Assembly in the Low Surface Brightness Dwarf Galaxy KDG215