Synthecium subventricosum Bale, 1914

Stems monosiphonic, flexuous, to 2 cm long; no secondary branching, but a few tendrils given off distal ends of branches. Proximal stem internodes with 1-3 pairs of opposite hydrothecae; succeeding internodes 1.5-1.8 mm long, a pair of opposite hydrothecae in middle of internode, and a pair of opposite, distally situated hydrocladia.

Hydrothecae of variable shape, generally tubular, three quarters of length adnate to internode, free adcauline wall 0.07-0.15 mm long, fixed wall 0.42-0.45 mm; abcauline wall 0.38-0.44 mm long. A delicate internal sheath clearly visible in many hydrothecae. Margin of hydrotheca sinuous, slightly everted, 0.18-0.19 mm in diameter, a few marginal reduplications.

Colour: white, with trace of purple.