Thank you Saroj ji, Paradesi ji.
Checked the references given in EFI website:
As per [ref1], Z. rugosa is woody, armed straggler; thorns stout; branchlets rusty-tomentose; leaves orbicular, broadly elliptic, 8-15 x 5-10 cm, glabrous above, woolly below, obtuse, serrulate, base subcordate.
As per [ref2] Z. rugosa is an armed woody straggler, up to 6m tall. Leaves orbicular-rotund, 4-6 x 2.5-5 cm, 5-nerved, base cordate, margin serrulate, apex rotund.
In the photos, I couldn't find thorns, and the leaves don't seem (to my untrained eyes) woolly below (only [ref1] mentions woolly). I missed checking for both these details in the field. The leaves are not 5-nerved (only [ref2] mentions it).
I also checked Z. glabrata, as it is mentioned as unarmed in both the references.
As per [ref1], Z. glabrata is unarmed tree, up to 8m tall; leaves ovate to oblong-elliptic, 4-7 x 2.5-5 cm, glabrous or pubescent on the nerves beneath, obtuse or acute, crenate, base obtuse.
As per [ref2], Z. glabrata is unarmed tree, up to 8m tall; wood brown; branchlets tomentose. Leaves ovate, elliptic, or elliptic-oblong, 3-7.5 x 2.3-5 cm, glabrous, white woolly-tomentose beneath when young, base obtuse-subcordate, apex acute or crenate, petiole 3-9 mm.
In this case also, I couldn't make out the pubescent/tomentose nature from the photos.
Checked a few other Z. species, but they don't seem to match -- in those other species, either the leaves are hairy, or the nerves don't meet (in Z. caracatta).
I am completely new to all these details, and not sure how to conclude if it is Z. rugosa. :-)
Thank you.
-Arvindh