A new nematode species, Chromadorina tangaroa sp. nov. (Chromadorida: Chromadoridae) from the hull of a research vessel, New Zealand

Chromadorina is a globally distributed, largely marine nematode genus frequently found on a variety of organisms, including macro- and microalgae and crustaceans, as well as artificial substrates such as settlement plates and ship hulls. Here, Chromadorina tangaroa sp. nov. is described from filamentous seaweed growing on the hull of RV Tangaroa anchored in Wellington, North Island of New Zealand. It is characterized by body length 763–1,086 μm, and pore of secretory-excretory system located at or near level of teeth. Males have spicules with rounded capitulum followed by a narrower shaft and blade tapered distally, a gubernaculum as long as the spicules, and three cup-shaped precloacal supplements, and females are characterized by a cuticularized prevulvar pad, vagina located at 46–48% of body length from anterior, and vagina anteriorly directed. Chromadorina tangaroa sp. nov. is the first species of the genus to be described from New Zealand, but it is unclear whether it is native to the region because it may have dispersed as part of ship hull biofouling communities. Long-distance transport of nematodes through ship hull biofouling may be a common occurrence, but too little is known about the occurrence of nematodes on ship hulls to gauge the potential effect of shipping on nematode species distributions.