Sulculeolaria angusta features a front nectophore during the polygastric phase. This nectophore lacks ostial teeth, and both the hydroecium and ostial teeth are not present. There are no commissural canals. The mouth plate measures approximately 3.25 mm in length and is thicker towards the base, with a small central prominence. Its margin is not rounded but has a noticeable notch, and the apex is broad and truncated.