Ventromma irregularis
A small species, with fragile and lax colonies that collapse out of water.
A small species, with fragile and lax colonies that collapse out of water.
Stems to 15 mm high, arising irregularly from a reptant hydrorhiza. Proximal stem region lightly fascicled, stems sparsely branched with one or two orders of branching. Cauline internodes long, narrow, smooth, nodes transverse to slightly oblique, perisarc of internodes thin; hydrocladia alternate, arching gracefully away from a short apophysis with transverse distal node.
Hydrocladial internodes long, slender, smooth, nodes transverse to slightly oblique, no intranodal septa; most internodes thecate but some hydrocladia with an athecate segment.
Hydrotheca on distal third of internode, cup-shaped, adcauline wall lying parallel to but free of internode; abcauline wall contiguous with internode, curving upwards; margin circular, rim faintly everted, perpendicular to hydrothecal axis and tilted proximally away from axis of internode.
Nematothecae all of same size and shape, bithalamic, minute, mesial inferior distant from hydrotheca, mesial superior near distal node; one cauline nematotheca above axil of apophysis and one on internode below apophysis, a small mamelon on distal side of apophysis facing axillar nematotheca.
South Africa and Australia.
Subtidal, epizoic on benthic invertebrates and hard substrates.