Psolus antarcticus ( Philippi, 1857 )

Davey, Nicola, 2013, The Psolidae of New Zealand and some additions to the Macquarie Ridge fauna (Echinodermata: Holothuroidea: Psolidae), Memoirs of Museum Victoria 70, pp. 51-67 : 53-55

Psolus antarcticus ( Philippi, 1857)

Table 1, Figures 1, 3A–C

Holothuria antarctica Philippi, 1857: 133 .

Psolus antarcticus Ludwig, 1898: 53 , pl. 3-figs 34–36 (complete synonymy).— Ekman, 1923: 42, figs 31–33; 1925: 139, text-fig. 34.— Deichmann, 1947: 339.—Pawson, 1968a: 19, fig. 2 (1–4).— Mackenzie and Whitfield, 2011: 26–28 .

Psolus neozelanicus Mortensen, 1925: 362 , figs 44–45.— Dawbin, 1950: 35, pl. 1-fig. 2.— Pawson, 1970: 28.— Mah et al., 2009: 398.— Mackenzie and Whitfield, 2011: 28.

Material examined. Macquarie Ridge: NIWA 40954 (2) Stn TAN0803/93, 56.25°S 158.51°E, 676–750 m, 16/04/2008; NIWA 40887 (16) Stn TAN0803/94, 55.37°S 158.38°E, 501–577 m, 15/04/2008; NIWA 40758 (9) Stn TAN0803/91, 55.36°S 158.42°E, 501–630 m, 15/04/2008; NIWA 40824 (1) Stn TAN0803/93, 55.35°S 158.43°E, 605–709 m, 15/04/2008; NIWA 40853 (1) Stn TAN0803/94, 55.37°S 158.38°E, 501–577 m, 15/04/2008; NIWA 68127 (1) Stn E227, 54.68°S 158.91°E, 148 m, 24/02/1965; NIWA 76248 (1) Stn C734, 53.91°S 158.91°E, 360 m, 25/11/1961. New Zealand, Hikurangi Margin: NIWA 65685 (8) Stn F 767, 41.51°S 176.11°E, 1205 m, 21/08/1966 ; NIWA 63356 (1) Stn TAN1004/36, 41.59°S 175.85°E, 1150–1177 m, 18/04/2010; NIWA 63906 (9) Stn TAN1004/100, 42.13°S 174.54°E, 1375–1480 m, 24/04/2010; NIWA 71936 (19) Stn G954, 42.61°S 175.97°E, 1190 m, 02/06/1973. New Zealand, Chatham Rise: NIWA 30627 (2) Stn TAN0705/94, 44.56°S 178.4°E, 1110–1119 m, 10/04/2007 ; NIWA 30629 (1) Stn TAN0705/98, 44.56°S 178.4°W, 1074–1081 m, 10/04/2007; NIWA 30630 (8) Stn TAN0705/98, 44.56°S 178.4°W, 1074–1081 m, 10/04/2007; NIWA 63968 (2) Stn Z10820, 41.59°S 175.77°E, 1400 m, 26/05/2001; NIWA 63931 (1) Stn TAN1004/103, 42.13°S 174.53°E, 1169–1213 m, 25/04/2010; NIWA 71146 (1) Stn 2253/20, 44.7°S 176.6°E, 794–1156 m, 29/05/2006; NIWA 76355 (1) Stn S1065H, 44.14°S 178.5°E, 990 m, 05/05/1997.

Description. See Mackenzie and Whitfield (2011) for the most recent description of this species including photos of the ossicles. All material examined here concurs with this recent description and any variations or amendments are discussed below.

Colour. Preserved: white and pale brown; dorsal and lateral scales have pale brown centres with a white periphery. This differs from Mackenzie and Whitfield (2011), in which specimens examined were white only.

Distribution. Previously reported from South America (Magellanic region), South Georgia, Macquarie Island, 100– 1666 m; extended here to New Zealand and further locations along Macquarie Ridge, 360–1480 m.

Remarks. Mackenzie and Whitfield (2011) recently confirmed the distribution of Psolus antarcticus ( Philippi, 1857) as extending into Australian and Macquarie Island waters. Herein, we confirm that P. antarcticus is known from the continental slope around New Zealand, including the Chatham Rise. The specimens examined here morphologically match the type description, however, we do note that the colour of this relatively fresh material has brown scale centres compared with the uniform white colour previously reported. The depth distribution of the New Zealand material is within the known range of 100–1666 m.

Psolus neozelanicus Mortensen, 1925 was based on two small specimens from east of North Cape, New Zealand. It has not been collected since. This species was briefly discussed in Mackenzie and Whitfield (2011). We further judge from the type description of its knobbed perforated plates (four central perforations recognisable) and five symmetrical valves that this species is a subjective junior synonym of Psolus antarcticus . Mortensen (1925) discusses the ventral ossicles with four central perforations, which are well known in P. antarcticus . His illustrations (p. 363), however, tend to show ossicles with slightly more numerous perforations that are present dorsally, rather than ventrally. We re-examined some of our smaller (7–9 mm) P. antarcticus specimens (NIWA 40758) and found the ventral ossicles predominantly with four, but sometimes with up to six perforations like the larger P. antarcticus . Ventral ossicles were sparse in both of our small specimens. All specimens previously identified as P. neozelanicus in both the NIC and Museum of Victoria (MV) have been re-examined and determined to be P. antarcticus or P. parantarcticus Mackenzie and Whitfield, 2011 .