Hippothoa peristomata Gordon 1984

Hippothoa peristomata Gordon, 1984

(Fig. 10B, C, E, F)

Hippothoa peristomata Gordon, 1984: 111, text-fig. 10E, pl. 43E–G; Gordon et al. 2009: 291.

Material examined. Holotype: NIWA 7429 (H-330), Kermadec Ridge (no data). Other material: NIWA 22948, 35.7415° S, 178.4983° E, 312 m; NIWA 76400, 37.6152° S, 177.0957° E, 165–170 m; NIWA 93782, 120856, 36.9078° S, 169.8463° W, 1013 m.

Remarks. The species was named for the extremely elevated orificial region (Fig. 10B), shown here in profile for the first time (Fig. 10E). The ooecium of the terminal ovicell is relatively large and globular, and a little wider than the maternal zooid (Fig. 10C). The holotype colony had unusual kenozooids and it appears that these were not anomalous as they also occur in a sample from the Louisville Seamount Chain. They are almost the same size and shape as autozooids but instead of a tall elevated orifice there is only a smooth rounded convexity (Fig. 10F); this does not appear to be a reparative feature.

Only one ancestrula has been found and it is kenozooidal.

Hippothoa peristomata was first discovered in a sample from the Kermadec Ridge but the label with station data was lost. Further, the type material lacked an ancestrula. The species has subsequently been identified three times in later-collected samples—from the outer continental shelf south of White Island, Bay of Plenty, at 165–170 m, on the southern Kermadec Ridge near Rumble III Seamount at 312 m, and on the Louisville Seamount Chain at 1013 m. The substratum is volcanic rock.