Amphisbetia minuta (Bale, 1882)

Hydrorhiza broad, flattened, with a delicate flange on each side and flexion joints passing inwards from the edge into the coenosarc.

Stems simple, each bearing five to seven pairs of hydrothecae. Stems beginning with two deep, narrow, opposed V-shaped hinge joints, internodes thereafter with a pair of hydrothecae seated on an urn-shaped infrathecal chamber.

Hydrothecal pairs joined anteriorly, separated posteriorly, bases of hydrothecae flat or slightly convex. Anterior hydrothecal wall straight and parallel with internode, abcauline wall more or less parallel to the internode for proximal three quarters of its length, then diverging outwards to the margin. Abcauline wall usually undulated, basally turgid, with a slight constriction at junction with the infrathecal chamber. Hydrothecal margin facing outwards with two distinct lateral teeth with slightly rounded cusps. Proximal infrathecal chamber with two slender, cylindrical tubules with very delicate perisarc, directed outward and downward from the lowest point on opposite sides of the abcauline wall. A few tubules sometimes present on infrathecal chambers further up the stem.

Gonothecae given off from proximal infrathecal chamber, large, subcircular, flattened, widest about the middle, perisarc moderately thick, smooth, pedicel narrow, aperture elliptical with a small, raised collar, a row of tiny denticles within, operculum thick.