Acryptolaria norfolkensis n. sp.

(Figs 20; 30; 32D; Table 21)

TYPE MATERIAL. — Norfolk Ridge. BIOCAL 1, stn DW 36, 23°08.647’- 23°08.900’S, 167°10.994’- 167°11.296’E, 650-680 m, 29.VIII.1985, 5 stems up to 80 mm high and 2 unbranched incipient stems up to 8 mm high, on hard substratum; plus a c. 5 mm long fragment. Of this lot 1 70 mm high stem with 2 incipient stems on rock fragment, holotype (MNHN-Hy.2009-0168); 1 30 mm long stem with side branch, paratype (RMNH-Coel. no. 31521).

OTHER MATERIAL EXAMINED. — Norfolk Ridge. CHALCAL 2, stn DW 81, 23°19.60’S, 168°03.40’E, 320-340 m, 31.X.1986, 1 basally broken stem c. 17 mm high in slide (MNCN 2.03/399).

MUSORSTOM 4, stn DW 220, 22°58.5’S, 167°38.3’E, 505-550 m, 29.IX.1985, 1 stem c. 27 mm high (RMNH-Coel. no. 35040, slide 491).

ETYMOLOGY. — The specific name norfolkensis refers to the Norfolk Ridge, the area where this species was collected. It is an adjective in genitive singular.

ECOLOGY AND DISTRIBUTION. — Acryptolaria norfolkensis n. sp. was collected at depths between 320 and 680 m in the Norfolk Ridge area.

DESCRIPTION

Stems up to 80 mm high, robust and strongly polysiphonic.Branching frequent(up to fourth-order branches observed) and irregular, yet more or less in one plane (Fig. 32D). In general, primary branches well developed, giving rise to lower-order branches; occasional anastomoses are present. Branches straight (Fig. 20A), but distinctly widening at point where the hydrotheca becomes free (Fig. 20).

Hydrothecae alternately arranged in approximately one plane (Fig. 20 A-C), more or less cylindrical (Fig. 20), but with a clear decrease of diameter at their basal third; minimum diameter at the base. Distal part of hydrotheca roughly straight; strongly directed outwards. Adcauline wall adnate for almost two-thirds of its length (adnate/free ratio 1.8), either convex throughout or straight at free portion; abcauline wall slightly concave, straight at distal part, with strong perisarc development reaching as far downwards as hydrotheca underneath.Hydrothecal aperture circular, obliquely directed upwards, forming an angle of 20-50° with long axis of branch. Rim even, frequently with a few short renovations.

Large nematocysts relatively large and fusiform (Fig. 30).

Coppinia not observed.

REMARKS

Acryptolaria norfolkensis n. sp. is close to A. disordinata n. sp. in general appearance of the stems that frequently branch in one plane, in the straight branches that widen markedly at the point where the hydrotheca becomes free, in the hydrothecae being directed outwards from their base, and in the size of the nematocysts. However, they differ distinctly in the shape and size of the hydrothecae, A. norfolkensis n. sp. being a much more robust species with larger hydrothecae, in particular their diameter. The two species also differ in the larger free portion of the adcauline hydrothecal wall and in the distinct decrease in hydrothecal diameter over its basal third in A. norfolkensis n. sp.

In the general shape and size of the hydrothecae, Acrypolaria norfolkensis n. sp. also reminds A. bathyalis n. sp. However, they are clearly distinguishable because the latter is a less robust species, with branches not widening at the point where the hydrotheca becomes free, with a much shorter free adcauline hydrothecal portion, with a distinctly smaller hydrothecal diameter, with the hydrothecae directed outwards only distally and with smaller nematocysts.