The shell is small (6 mm), fusiform, whitish and with a blunt protoconch. The protoconch is paucispiral and smooth, consisting of about 1.5 whorls and measures about 0.7 mm in diameter and height. The teleoconch consists of somewhat more than 3 whorls. There is a strictly spiral sculpture with four and occasionally 3 spirals at the penultimate whorl. The body whorl has 10-11 spiral ribs. The aperture is high and large, ovate and about 52% of shell length. The outer lip is thickened at adult shells. The siphonal canal is short, straight and open.

The most closest species is Prosipho crassicostatus (Melvill & Standcn, 1907) . Both species are however easily to separate by the height of their aperture, which is about 43% of the shell length at P. crassicostatus and about 52% at P. grohae. Prosipho spiralis Thiele, 1912 seems to be a similar species at the first sight, too. It's very typical squarish protoconch however separates it not only from P. grohae but also from all other known Prosipho species. The shells of P. crassicostatus and P. spiralis are syntypes which will be designated as lectotypes in my revision of the genus Prosipho (to be published in the Atlas of Antarctic Mollusks).

TYPE LOCALITY
Weddel Sea, close to the Antarctic continent, 70°40.25'S - 7°40.07'W, 100m.