Bathycrinus australis A.H. Clark, 1907b

Eléaume, Marc, Bohn, Jens-Michael, Roux, Michel & Améziane, Nadia, 2012, Stalked crinoids (Echinodermata) collected by the R / V Polarstern and Meteor in the south Atlantic and in Antarctica, Zootaxa 3425, pp. 1-22 : 4-6

Bathycrinus australis A.H. Clark, 1907b

Figure 2 ; Tables 2–3 .

Synonymy: Bathycrinus aldrichianus Carpenter, 1884: 241 –243, pl. 7, pl. 7a (figs. 1–21), pl. 7b, pl. 8a (figs 4–5); Bathycrinus australis A.H. Clark, 1907b: 553 –554; Döderlein, 1912: 9–10, pl. 5 (fig. 1), pl. 6 (fig. 7); Ilycrinus australis A.H. Clark, 1915: 154 –155; Vaney & John, 1939: 661; Bathycrinus australis Gislén, 1938: 16 ; 1956: 61–62, pl. 1 (figs. 1–6); Mc Knight, 1973: 204–205; A.M. Clark, 1977: 162–164; Bathycrinus cf. aldrichianus Bohn, 2006: 7 –9, fig. 2A; Bathycrinus australis Mironov, 2008: 141 ,143.

Material examined. External morphological features of specimens examined ( Table 2 ) fall within the range of variation described by A.M. Clark (1977), especially with a flared radial ring and smooth flanged arms ( Fig. 2 A–B). Bohn (2006) reported only stalk fragments and a single incomplete juvenile crown from DIVA stations and attributed them to B. cf. aldrichianus mainly on biogeographical evidence. These specimens are attributed here to B. australis based the analysis of their stalk articulations.

Description of stalk articulations. The distal end of the stalk varies from several fused columnals bearing radicules that penetrate soft sediment ( Fig. 2 C) to robust ramification that encrust rocks or pebbles ( Fig. 2 E). Usually, the transition is gradual ( Fig. 2 D) between the mesistele which has columnals significantly higher than wide (ratio height to maximum diameter> 3 in mid mesistele), and the dististele in which columnals are nearly as high as wide ( Fig. 2 C, E). In the largest specimens, distal synarthries have a large extension of deep ligament fossae; each segment of the fulcral ridge is bottle-shaped and has two rows of 35–40 small crenulae underlining its axis ( Fig. 2 F–G). In the dististele of young specimens, synarthries resemble those of B. aldrichianus ( Fig. 2 H). Mesistele synarthries are well developed in juveniles and have larger and deeper ligamentary depressions ( Fig. 2 K–L), and medium-sized specimens have strongly rounded oval facets with the longest diameter perpendicular to the fulcral ridge. As growth increases, the fulcral ridge becomes relatively narrower around axial canal with convex lateral sides ( Fig. 2 I–J). Stalk articulations in B. australis and B. aldrichianus differ significantly, especially in their mesistele synarthries.

Occurrence. B. australis occurs in the South Atlantic with northern records from the deep Argentina plateau and Angola basin. It is also known from the Southern Ocean and the southern Indian Ocean from east of the Antarctic Peninsula to the Kermadec Trench and New Zealand ( Tables 2–3 ). The depth range is large and extends from 1525 m to 8210 m, possibly from 1488 to 8300 m.

cruises. *: after Bohn (2006).

Scotia 62°10’S – 41°20’W 3246 Vaney & John, 1939 1 specimen

Figures

FIGURE 2. Bathycrinus australis (ZSM 20020004). A – G, I – J: large specimen; H, K – L: juvenile specimen; A – B: views of crown; C: distal stalk with bases of thin roots; D: progressive transition from dististele to mesistele; E: other distal stalk with large roots encrusting pebble; F – H: distal synarthries; I – L: mesistele synarthries.

Tables

TABLE 2. Sampling stations of B. australis A. H. Clark, 1907 b collected during R / V Polarstern (PS) and R / V Meteor (M)

Cruise/Station	Location	Depth (m)	Catalogue n° Remarks
EASIZ I/PS 39/18 AGT4b	73°16.70’ S–21°25.50’W to 73°16.10’S–21°24.70’W	1538–1543	ZSM 20020004 10 specimens
DIVA I/M 48/1-327	19°59.2'S–3°00.9'E to 20°07.5'S–3°07.9'E	5439–5448	ZSM 20043082 1 stalk fragment *
DIVA I/M 48/1-334	19°12.5'S–3°49.0'E to 19°19.8'S–3°55.6'E	5425–5426	ZSM 20043081 3 stalk fragments *
DIVA I/M 48/1-337	18°18.9'S–4°42.7'E to 18°24.6'S–4°45.1'E	5392–5393	ZSM 20043085 8 stalk fragments * ZSM 20020069 1 stalk fragment *
DIVA I/M 48/1-339	18°19.4'S–4°42.1'E to 18°25.3'S–4°44.0'E	5392–5395	ZSM 20043083 7 stalk fragments *
DIVA I/M 48/1-344	17°06.2'S–4°41.7'E to 17°07.5'S–4°42.3'E	5415	ZSM 20043084 1 stalk fragment *
DIVA II/M 63/2-42	28°0,206’S–7°16,905’E to 28°4,029’S–7°20,821’E	5082–5089	ZSM 20070048 1 stalk fragment
ANDEEP II/PS 61/131-4	65°19.47’S–51°32.55’W to 65°19.78’S–51°31.41’W	3049–3052	ZSM 20043097 1 stalk fragment ZSM 20043086 1 broken crown
ANDEEP II/PS 61/132-3	65° 17.88’S–53°22.88’W to 65°17.35’S–53°22.89’W	2087–2084	ZSM 20043096 1 juvenile with prox- imal stalk
ANDEEP II/PS 61/134-3	65°19.54’S–48°05.47’W to 65°19.47’S–48°04.27’W	4060–4065	ZSM 20043098 1 large specimen
ANDEEP II/PS 61/138-4	62°57.80’S–27°52.14’W to 62°57.77’S–27°51.10’W	4543–4545	ZSM 20043095 1 specimen
ANDEEP III/ PS 67/057-2	69°24.50’S–5°19.27’W to 69°24.62’S–5°19.68’W	1819–1822	ZSM 20070049 1 specimen
ANDEEP III/PS 67/059-10	6730.37’S–03.74’E to 6730.27’S–04.34’E	4648–4648	ZSM 20070050 1 specimen
ANDEEP III/ PS 67/153-7	6319.31’S–6436.94’W to 6319.15’S–6437.18’W	2092–2118	ZSM 20070051 1 specimen
ANDEEP III/PS 67/153-8	63°19.21’S–64°37.07’W to 63°19.10’S–64°37.13’W	2108–2124	ZSM 20070052 235 specimens
ANT XXI/2/PS 65/109-1	70°47.88’S–11°21.56’W to 70°47.88’S–11°24.13’W	1488–1525	ZSM 20070047 ~90 specimens