STYLASTERIDAE (HYDROCORALS) FROM 



SOUTHERN SEA'S 



By Hjalmar Broch 



Professor at the University of Oslo 

 (Plates II-IV, Text-figs. 1-12) 



Specimens of Stylasterids(Hydrocorals) have been taken by the ships of the Discovery Investigations 

 at only a few stations. The Stylasteridae are on the whole comparatively scantily represented in 

 collections of deep-sea expeditions, because in localities favourable to their growth the nature of the 

 bottom makes collecting difficult. 



Nevertheless, the Discovery material is very interesting both from a taxonomic point of view, con- 

 taining as it does a peculiar new genus and two hitherto undescribed species, and also from the 

 zoogeographical data supplied by the localities. From two of the stations so much material was col- 

 lected that some impression of variation in the species Errina antarctica (Gray) can be obtained. This 

 species is evidently widely distributed in antarctic-subantarctic waters. 



Errina (Eu-Errina) antarctica (Gray, 1872) 



(PI. II, fig. 1 ; PI. IV, figs. 3-6) 



Porella antarctica Gray, Proc. Zool. Soc. Lond. 1872, p. 746, pi. 64, fig. 4. 



Labiopora antarctica Moseley, Philos. Trans. 1878, vol. 169, pp. 476, 480. Ridley, Proc. Zool. Soc. Lond. 1881, p. 105. 

 Errina gracilis von Marenzeller, Res. Voy. Belgica, Rapp. Sci., Zool. Anvers, 1903, p. 4, pi. i, figs. 1-4. 

 Errina antarctica Hickson, Proc. Zool. Soc. Lond. 1912, p. 887. Hickson, Bull. Mus. Hist. Nat. Paris, 1912, p. 2 (462). 

 Broch, Skr. d. Norske Vid.-Akad. Oslo, I. Mat.-Naturv. Kl. 1942, no. 3, p. 42, figs. 11, 12, pi. iv, fig. 12. 



St. 652. Burdwood Bank, 54 04' S, 6i° 40' W, 169-171 m. Net badly torn (hard bottom). 



St. 1948. 6o° 49-4' S, 52° 40' W, 490-610 m. 



St. 2200. Between Young and Sturge Is., Balleny Group, 67 09-6' S, 163° 27-7' E, 532-512 m. 



St. 2215. Off Antipodes Is., 49° 45-6' S, 178 48' E, 163-210 m. 



St. 2290. Off Falkland Is., 52 16-6' S, 58 06-8' W, 137-133 m. 



The colonies of Errina antarctica are in most cases rather coarse and heavily built, fan-shaped with 

 a distinct anterior and posterior side, the latter with none or only very few pores. The distal branchlets 

 have numerous pores and spines on all sides (see PI. II, fig. 1), but the spines tend to diminish and 

 disappear on the posterior side, which may be naked and all but poreless already some 1 cm. from the 

 top. The terminal branchlets carry spines on all sides and are cylindrical. They are differentiated into 

 a zooid-bearing anterior and a naked posterior side, with more or less pronounced flattening of the 

 branch, which in transverse section becomes more obviously oval, its greater diameter lying in the 

 plane of the fan. In the basal parts of larger colonies spines and zooids disappear also on the anterior 

 face of the main branches and stem. In many cases basal parts of the stem and main branches, where 

 pores have disappeared, grow so broad that they coalesce into one flat basal stem or trunk. 



It must be noted that the colonies may be partly incrusting. Whether a colony can spread over a 

 large area cannot be answered with certainty, but part of a colony from the Burdwood Bank apparently 

 has a horny black axis, because the hydrocoral has grown around the axis of a dead gorgonid and from 

 this part real branches arise (PI. II, fig. 1). 



The material from Sts. 2200 and 2290 is especially rich, indicating the range of variation in the 

 species. 



