Context :

Aims : We present a comprehensive dataset of optical and near-infrared photometry and spectroscopy of type Ia supernova ( SN ) 2016hnk , combined with integral field spectroscopy ( IFS ) of its host galaxy , MCG -01-06-070 , and nearby environment .
Our goal with this complete dataset is to understand the nature of this peculiar object .

Methods : Properties of the SN local environment are characterized by means of single stellar population synthesis applied to IFS observations taken two years after the SN exploded .
We perform detailed analyses of SN photometric data by studying its peculiar light and color curves .
SN 2016hnk spectra are compared to other 1991bg-like SNe Ia , 2002es-like SNe Ia , and Ca-rich transients .
In addition , abundance stratification modelling is used to identify the various spectral features in the early phase spectral sequence and the dataset is also compared to a modified non-LTE model previously produced for the sublumnious SN 1999by .

Results : SN 2016hnk is consistent with being a sub-luminous ( M _ { B } = -16.7 mag , s _ { BV } =0.43 \pm 0.03 ) , highly reddened object .
IFS of its host galaxy reveals both a significant amount of dust at the SN location , as well as residual star formation and a high proportion of old stellar populations in the local environment compared to other locations in the galaxy , which favours an old progenitor for SN 2016hnk .
Inspection of a nebular spectrum obtained one year after maximum contains two narrow emission lines attributed to the forbidden [ Ca ii ] \lambda \lambda 7291,7324 doublet with a Doppler shift of 700 km s ^ { -1 } .
Based on various observational diagnostics , we argue that the progenitor of SN 2016hnk was likely a near Chandrasekhar-mass ( M _ { Ch } ) carbon-oxygen white dwarf that produced 0.108 M _ { \odot } of ^ { 56 } Ni .
Our modeling suggests that the narrow [ Ca ii ] features observed in the nebular spectrum are associated with ^ { 48 } Ca from electron capture during the explosion , which is expected to occur only in white dwarfs that explode near or at the M _ { Ch } limit .

Conclusions :