Holotype: NTM C12958 alcohol preserved material, fertile colony, East Arm port site, Darwin Harbour, Northern Territory.
Other material: NTM C12615 Microslide from holotype, C12616, Microslide from holotype; NMV F86889 Microslide from holotype, East Arm port site, Darwin Harbour, Northern Territory.
Named for the type locality of Darwin Harbour, Northern Territory, Australia.
Colony stolonal, hydrorhiza tubular, reptant on stem and branches of host.
Hydrotheca arising from stolon at regular intervals, usually beside a hydrotheca of host. Hydrotheca long, narrow, tubiform, bending outwards from hydrorhiza and away from host; pedicel short, asymmetrically placed at base of hydrotheca, sometimes with a single twist. Diaphragm thin, concave, adjoined to wall by a ring of perisarc, better developed as a triangular shelf on adcauline wall. Margin circular, not everted, sometimes with a single replication; perisarc of hydrotheca moderately thick.
Hydranth with conical hypostome surrounded by 20 - 24 tentacles.
Gonotheca large, elongate conical, borne without pedicel on hydrorhiza, orifice distal, circular, operculum a single flap, perisarc of gonotheca thin. Nearly mature gonophore a single large eumedusoid; umbrella a small disk with four vestigial radial canals; four long rudimentary tentacles contracted into a wavy pattern; no velum or manubrium.
Colour: Hydrotheca white, gonotheca transparent to bluish-white, tentacles of gonophore white to pink, radial canals pink.
Northern Australia (Northern Territory).
Subtidal, epizoic on other hydroid species.