Figures 4, 5A–D.

Holotype. NMV F98987, stn SLOPE-6.

Paratypes. NMV F101923, stn SLOPE-6 (45 colonies, many with roots and opercula and mandibles).

Other specimens. NMV F101924, stn SLOPE-2 (7 colonies, 4 with roots); NMV F98988, stn SLOPE-7 (10 colonies, 2 with roots); NMV F101925, stn SLOPE-39 (1 colony with root); NMV F101926, stn SLOPE-40 (2 colonies); NMV F101927, stn SLOPE-45 (1 colony); NMV F101928, stn SLOPE-48 (1 colony); NMV F101929, stn SLOPE-53 (3 colonies).

Etymology. ecstasis (L.) – joy, with reference to the appearance of the orifice and paired lateral avicularia.

Diagnosis. Conescharellina with large, conical colonies, solid antapically. Zooid orifices in radial series, primary orifice with a rounded sinus. Avicularia very large, paired, elongated, lateral to orifice, orientated laterally and adapically. Root pores lunate.

Description. Colonies large, conical, wider than high, domed and stellate in early astogeny. Calcification finely mamillate. Zooids in apparently radial series, peristomes prominent marginally, particularly in young, stellate colonies. Primary orifice with a distinct, rounded sinus and paired condyles, adapical pore on the edge of the peristome. Avicularia paired, lateral, very large, with acutely triangular rostra, nearly always directed laterally and adapically; bar without a ligula. Adapical region with large avicularia and lunate root pores, each with a pair of small lateral avicularia. Antapical region solid, with radiating series of small avicularia and a few cancelli.

Colony diameter up to 4.7 mm, height 2.3 mm, number of whorls 6, number of zooids per whorl 8.

Remarks. The colonies of C. ecstasis sp. nov. are recognisable immediately, even to the naked eye, by the pairs of large avicularia, with mandibles of dark brown cuticle. The orientation of the rostra varies a little; those of the one specimen from stn SLOPE-45 being almost horizontal, like the rostra of C. biarmata. In contrast, one of the two colonies from stn SLOPE-7 has rostra directed almost adapically. Young colonies are stellate, with prominent peristomes, especially marginally, giving the colony a “ Trochosodon -like” appearance (Fig. 5A). C. ecstasi s differs completely from C. biarmata in colony shape and size, the characters of the primary orifice, and lack of avicularian ligulae. Except for stn SLOPE-6, only a few specimens of C. ecstasis were present at each of the eight SLOPE stations. The two colonies of C. biarmata sensu stricto from stn SLOPE-19 were easily distinguished by their much smaller dimensions and orientation of avicularia. All records of C. ecstasis are from deep water. The SLOPE stations range from south-eastern New South Wales, to eastern Victoria and Tasmania. The bathymetric range of records is from 400 m to 1096 m.