Hippothoa peristomata Gordon, 1984

Gordon, Dennis P., 2020, New Hippothoidae (Bryozoa) from Australasia, Zootaxa 4750 (4), pp. 451-476 : 469

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.

Figures

FIGURE 10. Four species of Hippothoa: A, D, Hippothoa pacifica Gordon (NIWA 98202), respectively showing an ovicellate zooid in lateral view with a pristine ooecium perforated by two elevated apical pores (the curved part of a rim seen between them), and dimorphic ovicellate orifice (apical pseudoporous mucro eroded) and autozooidal orifice; B, C, E, F, Hippothoa peristomata Gordon, respectively showing a frontal view of two autozooids (NIWA 94240), an ovicellate zooid (NIWA 94240), an autozooid in lateral profile (NIWA 120856) and a kenozooid (NIWA 94240); G, H, Hippothoa flagellum Manzoni (part NHMUK 97.5.1.793), autozooidal orifice and dimorphic female orifice; I, J, Hippothoa watersi Morris (NIWA 144795), autozooidal orifice and dimorphic female orifice. Scalebars: A, E, F, 200 μm; B, 300 μm; C, D, 100 μm; E, F, 200 μm; G–J, 20 μm.